VAR-501-WECC-4

Status: Original and derived artifacts are available for this document.

Download: pdf

Exhibit A
Proposed Regional Reliability Standard
VAR-501-WECC-4 – Power System Stabilizer

Exhibit A-1
Proposed Regional Reliability Standard
VAR-501-WECC-4 – Power System Stabilizer
(Redline)

VAR‐501‐WECC‐43.1 – Power System Stabilizer

A. A.

Introduction

1. Title:

Power System Stabilizer (PSS)

2. Number: VAR‐501‐WECC‐3.14
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, that meetmeeting the definition of Commercial Operation.
6. Effective Date: The first day of the first quarter following regulatory approval, except
for Requirement R3.
For units placed in first‐time service after regulatory approval, Requirement R3 is
effective the first day of the first quarter following final regulatory approval.
For units placed in service prior to final regulatory approval, Requirement R3 is effective
the first day of the first quarter that is five years after regulatory approval.
B.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
 The effective date of this standard;
 The PSS’s Commercial Operation date; or
 Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.

Page 1 of 14

VAR‐501‐WECC‐43.1 – Power System Stabilizer

For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]


Component failure



Testing of a Bulk Electric System Element affecting or affected by the PSS



Maintenance



As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:


A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.



Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter‐area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.

Page 2 of 14

VAR‐501‐WECC‐43.1 – Power System Stabilizer

3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.
If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start‐up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]


The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.



The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start‐up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
For auditing purposes The first bullet of Requirement R4, bullet one only applies to
equipment on its initial (first energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 14

VAR‐501‐WECC‐43.1 – Power System Stabilizer

C. Compliance
C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority
: “Compliance Enforcement Authority” means NERC or the Regional Entity, or any entity
as otherwise designated by an Applicable Governmental Authority, in their
respective roles of monitoring and/or enforcing compliance with mandatory and
enforceable Reliability Standards in their respective jurisdictions.
1.2 Compliance Monitoring and Assessment Processes


Compliance Audits



Self‐Certifications



Spot Checking



Compliance Investigations



Self‐Reporting



Complaints

1.3 . Evidence Retention
: The following evidence retention periodsperiod(s) identify the period of time an entity
is required to retain specific evidence to demonstrate compliance. For instances
where the evidence retention period specified below is shorter than the time since
the last audit, the Compliance Enforcement Authority may ask an entity to provide
other evidence to show that it was compliant for the full ‐time period since the last
audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.


Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.4 Additional Compliance Information
None

D. Regional Differences
None

Page 4 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer
Attachment DB

Table of Compliance Elements
1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 5 of 14

VAR‐501‐WECC‐43.1 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

R1

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

R2

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

R3

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a non‐
operational PSS as required in
Requirement R5.

Page 6 of 14

VAR‐501‐WECC‐43.1 – Power System Stabilizer

Page 7 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Page 8 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR‐STD‐002b‐1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR‐
501‐WECC‐1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR‐501‐WECC‐2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR‐501‐WECC‐3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

TBDSeptember 26,
2017

TBDFERC letter order issued
approving VAR‐501‐WECC‐3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non‐substantive
changes were
approved by the

Page 9 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

an information‐only filing to
NERC.

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information‐only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale‐dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

Page 10 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to dampendamp the low‐frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while still allowing for some of these
units to be out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either of the triggering eventsevent
described in Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non‐active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this
standardStandard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this standardStandard while also allowing the Generator Owner to create a unit‐
specific operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non‐active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator‐turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 11 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this standard’sStandard’s previous version, the logged hours were totaled quarterly
to meet the 98% in‐service requirement. Instead of documenting the number of hours
excluded, this Requirement simplifies the process by allowing the Generator Operator to
communicate to the Transmission Operator the circumstances that render the PSS unavailable
to the Transmission Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable wash‐outwashout time constants, the Requirement
specifies 0.2 Hz as the applicable threshold. The 0.2 Hz threshold more closely aligns with the
observed oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher‐frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed‐loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 12 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward to ensureensuring that a unit is
tuned, Requirement R5 looks backward. Specifically, the language in Requirement R5,
“becoming incapable,” indicates the unit was previously capable of meeting the tuning
requirements in Requirement R3, but is no longer capable. Restated, Requirement R5 addresses
units that were previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24‐month time frame is sufficient to return a functional, operating PSS to service.

Page 13 of 14

VAR‐501‐WECC‐3.14 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR‐501‐WECC‐3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR‐501‐WECC‐3

TBD

TBD

Inactive Date

Page 14 of 14

Exhibit A-2
Proposed Regional Reliability Standard
VAR-501-WECC-4 – Power System Stabilizer
(Clean)

VAR-501-WECC-4 – Power System Stabilizer

A. Introduction
1. Title:

Power System Stabilizer (PSS)

2. Number: VAR-501-WECC-4
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, meeting the definition of Commercial Operation.
6. Effective Date:

The first day of the first quarter following regulatory approval.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
• The effective date of this standard;
• The PSS’s Commercial Operation date; or
• Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.
For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]
•

Component failure
Page 1 of 11

VAR-501-WECC-4 – Power System Stabilizer

•

Testing of a Bulk Electric System Element affecting or affected by the PSS

•

Maintenance

•

As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:
•

A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.

•

Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter-area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.
3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.

Page 2 of 11

VAR-501-WECC-4 – Power System Stabilizer

If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start-up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]
•

The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.

•

The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start-up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
The first bullet of Requirement R4 only applies to equipment on its initial (first
energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 11

VAR-501-WECC-4 – Power System Stabilizer

C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority: “Compliance Enforcement Authority” means
NERC or the Regional Entity, or any entity as otherwise designated by an
Applicable Governmental Authority, in their respective roles of monitoring and/or
enforcing compliance with mandatory and enforceable Reliability Standards in
their respective jurisdictions.
1.2. Evidence Retention: The following evidence retention period(s) identify the period
of time an entity is required to retain specific evidence to demonstrate
compliance. For instances where the evidence retention period specified below is
shorter than the time since the last audit, the Compliance Enforcement Authority
may ask an entity to provide other evidence to show that it was compliant for the
full-time period since the last audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.
•

Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 4 of 11

VAR-501-WECC-4 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

R1

Moderate VSL

High VSL

Severe VSL

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a nonoperational PSS as required in
Requirement R5.

R2

R3

Page 5 of 11

VAR-501-WECC-4 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR-STD-002b-1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR501-WECC-1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR-501-WECC-2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR-501-WECC-3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

September 26, 2017

FERC letter order issued
approving VAR-501-WECC-3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non-substantive
changes were
approved by the

Page 6 of 11

VAR-501-WECC-4 – Power System Stabilizer

an information-only filing to
NERC.

4

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information-only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale-dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

TBD

Page 7 of 11

VAR-501-WECC-4 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to damp the low-frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while allowing for some units to be
out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either triggering event described in
Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non-active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this Standard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this Standard while also allowing the Generator Owner to create a unit-specific
operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non-active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator-turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 8 of 11

VAR-501-WECC-4 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this Standard’s previous version, the logged hours were totaled quarterly to meet
the 98% in-service requirement. Instead of documenting the number of hours excluded, this
Requirement simplifies the process by allowing the Generator Operator to communicate to the
Transmission Operator the circumstances that render the PSS unavailable to the Transmission
Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable washout time constants, the Requirement specifies 0.2 Hz
as the applicable threshold. The 0.2 Hz threshold more closely aligns with the observed
oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher-frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed-loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 9 of 11

VAR-501-WECC-4 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward ensuring that a unit is tuned,
Requirement R5 looks backward. Specifically, the language in Requirement R5, “becoming
incapable,” indicates the unit was previously capable of meeting the tuning requirements in
Requirement R3, but is no longer capable. Restated, Requirement R5 addresses units that were
previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24-month time frame is sufficient to return a functional, operating PSS to service.

Page 10 of 11

VAR-501-WECC-4 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR-501-WECC-3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR-501-WECC-3

TBD

TBD

Inactive Date

Page 11 of 11

Exhibit B
Summary of Development History and
Complete Record of Development

<Public>

Attachment E
Project Roadmap
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Informational Only Filing

Project Roadmap

Actions

Completed

1.

Standard Authorization Request (SAR) Filed

March 9, 2022

2.

WECC Standards Committee (WSC) approved the SAR

March 16, 2022

3.

Drafting Team (DT) Solicitation

March 30, 2022

4.

DT Meeting

June 21, 2022

5.

DT Meeting

June 28, 2022

6.

July 11, 2022

8.

Notice to Standard Email List for Proposed Non‐Substantive
Changes – No Substantive Changes Proposed
Posting 1 for Information Only – Comment/Response not
Required
Posting 1 Letter to WSC for Proposed Non‐Substantive Changes

9.

WSC Approved Non‐Substantive Changes

December 6, 2022

10.

WECC Board of Directors—Approved

Not Required

11.

Informational Filing pending at NERC

TBD

12.

NERC Board of Trustees Approves

TBD

7.

July 16, 2022
July 16, 2022

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Five-year Review

Overview
This Standard Authorization Request (SAR) was received March 7, 2022, and deemed complete the
same day. The WECC Standards Committee (WSC) vetted this SAR on March 16, 2022.
This SAR can be reviewed on the WECC-0148 project page at the Standard Authorization Request
accordion. If you have questions regarding this SAR, please contact W. Shannon Black at (503) 3075782.

Introduction
This is a request for five-year review of WECC Regional Reliability Standard VAR-501-WECC-3.1
Power System Stabilizer.1

Requester Information
Primary contact
•

First name:

W. Shannon

•

Last name:

Black

•
•

Email:
Phone:

[email protected]
(503) 307-5782

•

Organization name:

Western Electricity Coordinating Council (WECC)

Alternate
•

First name:

Donovan

•
•

Last name:
Email:

Crane
[email protected]

•

Phone:

Per the WECC Reliability Standards Procedures, Maintenance of RRSs and CRTs: ‘The WSC shall ensure that
each…RRS is reviewed at least once every five years from the effective date of the most recent version of the
document under review. If the review identifies needed changes, the WSC shall cause a remedial SAR to be filed.
If the review does not identify needed changes, no further action is required.”
1

155 N ort h 400 W est | Sui t e 200 | Sal t Lak e City , Ut ah 84103
www. wec c. or g

Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Five-year Review

Type of Request
This is a request for five-year review of a WECC Regional Reliability Standard.

Create, Modify, Retire or Review a Document
Requested Action (Select one)
•

This is a request for a five-year review of a WECC Regional Reliability Standard (RRS).

Document Type (Select one)
•

WECC Regional Reliability Standard

Issue
This project is assigned WECC Tracking Number WECC-0148.
This a request for a five-year review mandated per the WECC Reliability Standards Development
Procedures (Procedures).
Proposed Remedy
This request will review and update the entire document, as needed. No specific concerns have been
identified. The drafting team is authorized to recommend “no change” after reviewing the document.
Applicable Entities
Each function will be reviewed if affected. A dropdown will be provided. Check all applicable blocks.
4. Functional Entities:
4.1. Generator Operator
4.2. Generator Owner
Detailed Description
This request will review and update the entire document, as needed. No specific concerns have been
identified.
Affected Reliability Principles
•

Reliability Principle 1 — Interconnected bulk power systems shall be planned and operated in
a coordinated manner to perform reliably under normal and abnormal conditions as defined in
the NERC Standards.

2

Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Five-year Review

Document Information
NA

Reference Uploads
Provide Additional Comments (if needed).
NA

3

WECC Standards Committee
Meeting Agenda
Virtual

Virtual meeting link | Dial-in Number: 1-415-655-0003, Attendee Access Code: 2456 527 7931

1.

Welcome, Call to Order—James Avery

2.

Review WECC Antitrust Policy—Steven Rueckert
WECC Antitrust Policy.
Please contact WECC legal counsel if you have any questions.

3.

Approve Agenda—James Avery

4.

Review and Approve Previous Meeting Minutes—James Avery
Approval Item: December 7, 2021, minutes

5.

Review of Previous Action Items—W. Shannon Black
Standards Voting Segment Representatives; Drafting Team Nominees; Charter and Glossary
Review

6.

Request to Approve Standard Authorization Request
WECC-0148 VAR-501-WECC-4, Power System Stabilizer, Five-year Review

7.

Request to Approve Drafting Nominations—W. Shannon Black
WECC-0146 TPL-001-WECC-CRT-4, Transmission System Planning Performance
WECC-0147 BAL-004-WECC-3, ATEC Five-year Review with Focus on Requirement R1

8.

Standard Voting Segment Criteria Application—W. Shannon Black

9.

Reports—Various
SVS 6 welcomes Tim Kelley to the WSC

10.

Action Without a Meeting—W. Shannon Black
No report

11.

Public Comment

WSC Meeting Agenda—March 16, 2022

12.

Review of New Action Items—W. Shannon Black

13.

Review Upcoming Meetings
To Be Determined ..................................................................................... TBD

14.

Adjourn

2

Black, Shannon
From:
Sent:
Subject:

Black, Shannon
Wednesday, 30 March, 2022 10:50 AM
WECC-0148 VAR-501-WECC-4 Notice of Drafting Team Solicitation

WECC-0148 VAR-501-WECC-4 Power System Stabilizer – Five-year Review
Drafting Team nominations are being solicited for the following project:
• WECC-0148 VAR-501-WECC-4 Power System Stabilizer - Five-year Review
This project will complete a five-year review mandated per the WECC Reliability Standards
Development Procedures (Procedures). This request will review and update the entire
document, as needed. No specific concerns have been identified. The drafting team is
authorized to recommend “no change” after reviewing the document.
If you have an interest in participating on this drafting team, please submit a “DT
Nomination Form” found on the Standards Under Development Page. From the Tracking
Number drop down menu, please select “WECC-0148.”
Nominations will be addressed at the next scheduled WECC Standards Committee (WSC)
meeting.

W. Shannon Black, JD
WECC Consultant, Standards Processes
(503) 307-5782
[email protected]

1

WECC-0148
VAR-501-WECC-4
Power System Stabilizer
Drafting Team Meeting Agenda
Virtual
Webinar Link | Password: WECC | Dial‐in Number: 1‐415‐655‐0003, Attendee Access Code: 2456 499 7510
June 21, 2022, 10:00 a.m. to 12:00 p.m.

1.

Welcome, Call to Order, Introductions—W. Shannon Black

2.

Review WECC Antitrust Policy—W. Shannon Black
WECC Antitrust Policy.
Please contact WECC legal counsel if you have any questions.

3.

Approve Agenda

4.

Review and Approve Previous Meeting Minutes
Approval Item: No Previous Minutes

5.

Review of Previous Action Items—W. Shannon Black

6.

Drafting—W. Shannon
Standard Authorization/Scope Review; Review of Development Principles

7.

Public Comment

8.

Review of New Action Items

9.

Review Upcoming Meetings
June 28, 2022, 10:00 a.m. to 12:00 p.m. ...................................................Virtual
TBD, 10:00 a.m. to 12:00 p.m. ..................................................................Virtual
All DT meeting announcements are for Mountain Time.

10.

Adjourn

WECC-0148 VAR-501-WECC-4 PSS Drafting Team
Meeting
Virtual
10:00 a.m.—12:00 p.m. Mountain Time, Tuesday, June 28, 2022
Learn More

Black, Shannon
From:
Sent:
Subject:

Black, Shannon
Monday, July 11, 2022 4:05 PM
WECC-0148 VAR-501-WECC-4 – No Substantive Changes Recommended

WECC-0148 VAR-501-WECC-4 – No Substantive Changes Recommended

Recommendation
The WECC-0148 VAR-501-WECC-4 (VAR), Power System Stabilizer, Drafting Team (DT) is
recommending that no changes be made to the Standard. If the WECC Standards Committee (WSC)
accepts that recommendation, an information-only filing at NERC is recommended.

Overview
On June 21, 2022, the DT began a five-year review of the Standard as required by the WECC
Reliability Standards Development Procedures (Procedures). On July 1, 2022, after reviewing the
entire document during multiple public meetings, the DT unanimously agreed that no Substantive
Changes should be made to the Standard.

Non-Substantive Changes
The DT is recommending the following Non-Substantive Changes:


Updates to the document template, numbering, and boilerplate sections as provided by
NERC



Removal of stale-dated verbiage included in the Effective Date



Removal of the redundant phrase, “[F]or auditing purposes….” From Measure M4



Updates to syntax



Correction of “[s]tandard” to “[S]tandard”



Correction of “dampen” to “damp” in the Rationale and Guidance section

For more information, a redlined version showing the Non-Substantive Changes will be posted to
the WECC-0148 Home Page, on the Posting 1 For Comment accordion. If you have comments or
concerns regarding the recommendation, please contact W. Shannon Black.

1

W. Shannon Black, JD
WECC Consultant, Standards Processes
(503) 307-5782
[email protected]

2

<Public>

Response to Comments
Posting 1—45-Day at NERC
August 16 through September 29, 2023
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Information Only Filing

Posting 1—45-Day NERC
The WECC-0148 VAR-501-WECC-4, Power System Stabilizer Drafting Team (DT) thanks everyone who
submitted comments on the proposed project. WECC-0148 is an information-only filing proposing no
Substantive changes. 1

Posting
This project was posted for comment by NERC from August 16, 2023, through September 29, 2023.
NERC distributed notice for the posting on August 16, 2023.
NERC asked stakeholders to provide feedback on the proposed project through a standardized
electronic template.
NERC reported there “were 9 sets of responses, including comments from approximately 14 different
people from approximately 9 companies representing 4 of the Industry Segments.”
After review of the NERC-provided document, WECC found responses from seven organizations
(some with member organization subcomponents), and 13 persons identified in the following Table of
Respondents.

Location of Comments
All comments provided to WECC by NERC can be reviewed in their original format on the WECC-0148
project page under the “Submit and Review Comments” accordion.

Changes in Response to Comment
After consideration of all comments received, no further changes were made to this project.

The terms Substantive and Non-Substantive are defined terms found in the WECC Relibaility Standards
Development Procedures.
https://www.wecc.org/Reliability/WECC%20Reliability%20Standards%20Development%20Procedures%20%20FERC%20Approved%2009-13-2021.pdf
1

155 No rt h 400 We st | Suit e 200 | Sa lt Lake Cit y , U ta h 84103
www.we c c .o rg

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Minority View
No minority views were raised.

Proposed Effective Date
The proposed Standard can be implemented immediately upon receipt of final regulatory approval.

Information Only—No Substantive Changes
This project represents an “Information Only” filing with no Substantive changes.
Per the WECC Relibaility Standards Development Procedures (Procedures), if no Substantive changes
are requested to a Regional Standard, no further due process is required. Specifically, WECC Board of
Directors (Board) approval is not required.
On July 11, 2022, a list2 of proposed Non-Substantive changes was distributed to the Standards Email
List (SEL) inviting comments or concerns to be forwarded to WECC Standards staff. A redline and a
clean version of the project was posted on the WECC-0148, Posting 1 for Comment accordion. No
comments were received.
On July 16, 2022, WECC posted a letter3 to the WSC informing the WSC of its scope and authority to
address an information only filing. The letter was published to the WECC-0148 home page on the
Posting 1 for Comment accordion.
On December 6, 2022, during a duly noticed WSC meeting, the WSC reviewed the letter from July 16,
2022, and was briefed on the WSC’s Procedural authority to approve the project with no further due
process, so long as all changes were deemed Non-Substantive.
The WSC concurred4 that all proposed changes were Non-Substantive. Because the proposed changes
are all Non-Substantive, the WSC also concurred that neither a posting for comment, ballot, Board
approval, nor an Implementation Plan were required per the Procedures.

Table of Respondents
Organization

1

ACES Power Marketing (ACES)

Bob Soloman, Jodirah Green, Kris Carper

2

Arizona Public Service Company (APS)

Daniel Atanasovski

3

Avista Corporation

Glen Farmer, Mike Magruder, Robert Follini

https://www.wecc.org/Administrative/WECC-0148%20Notice%20of%20No%20Substantive%20Change.pdf
https://www.wecc.org/Reliability/WECC-0148%20VAR-501-WECC-3.1%20%20Letter%20to%20WSC%20Requesting%20Information%20Only%20Filing%20-%20FINAL.docx
4 https://www.wecc.org/Administrative/2022-0316%20WSC%20Proposed%20Meeting%20Minutes%20for%20approval%202022-12-06-2022%20%20FINAL%20FROM%20TECH.docx
2
3

2

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Organization

4

BC Hydro and Power Authority (BC)

Adrian Andreoiu, Helen Hamilton Harding,
Hootan Jarollahi

5

Bonneville Power Administration (BPA)

Andrea Jessup

6

Salt River Project (SRP)

Israel Perez

7

United States Bureau of Reclamation

Richard Jackson

(USB)

Contacts and Appeals
If you feel your comment has been omitted or overlooked, please contact W. Shannon Black, WECC
Consultant, at (503) 307-5782. In addition, there is a WECC Reliability Standards appeals process.

3

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Index to NERC-provided Questions, Comments, and Responses
Question
1) Do you agree the proposed Regional Reliability Standard was developed in a fair and open
process, using the associated Regional Reliability Standards Development Procedure?
2) Does the proposed Regional Reliability Standard pose an adverse impact to reliability or
commerce in a neighboring region or interconnection?
3) Does the proposed Regional Reliability Standard pose a serious and substantial threat to public
health, safety, welfare, or national security?
4) Does the proposed Regional Reliability Standard pose a serious and substantial burden on
competitive markets within the interconnection that is not necessary for reliability?
5) Does the proposed Regional Reliability Standard meet at least one of the following criteria
a. The proposed Regional Reliability Standard has more specific criteria for the same
requirements covered in a continent-wide standard.
b. The proposed Regional Reliability Standard has requirements that are not included in
the corresponding continent-wide standard.
c. The proposed regional difference is necessitated by a physical difference in the Bulk
Power System.

4

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Comment Summary. For proposed changes and avenues forward, please see the preamble.
1) Question 1—Do you agree the proposed Regional Reliability Standard was developed in a fair and
open process, using the associated Regional Reliability Standards Development Procedure?
Commenter

Comment or Response

ACES

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

Yes

Response

5

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

6

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 2— Does the proposed Regional Reliability Standard pose an adverse impact to
reliability or commerce in a neighboring region or interconnection?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

7

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

8

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 3— Does the proposed Regional Reliability Standard pose a serious and substantial
threat to public health, safety, welfare, or national security?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

9

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

10

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 4— Does the proposed Regional Reliability Standard pose a serious and substantial
burden on competitive markets within the interconnection that is not necessary for reliability?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

11

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

12

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.
1) Question 5—Does the proposed Regional Reliability Standard meet at least one of the following
criteria:
d. The proposed Regional Reliability Standard has more specific criteria for the same
requirements covered in a continent-wide standard.
e.

The proposed Regional Reliability Standard has requirements that are not included in the
corresponding continent-wide standard.

f.

The proposed regional difference is necessitated by a physical difference in the Bulk Power
System.

Commenter

Comment or Response

ACES

Yes. Thank you for the opportunity to comment.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

13

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

BC

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

Yes. While there are regional and physical differences, the
changes proposed are mainly grammatical and all are minor.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

14

Letter to WSC Requesting
Information-Only Filing

Recommendation
The WECC‐0148 VAR‐501‐WECC‐4 (VAR), Power System Stabilizer, Drafting Team (DT) is
recommending that no changes be made to the Standard. If the WECC Standards Committee (WSC)
accepts that recommendation, an information‐only filing at NERC is recommended.

Overview
On May 2, 2016, a WECC Ballot Pool approved VAR‐501‐WECC‐3, Power System Stabilizer, after eight
postings for comment. On April 28, 2017, FERC approved the Standard via letter order followed by
Version 3.1 errata on September 26, 2017. Between 2016 and 2022, no known concerns were raised
regarding the text the of the Standard.
On June 21, 2022, the DT began a five‐year review of the Standard as required by the Procedures. On
July 1, 2022, after reviewing the entire document during multiple public meetings, the DT unanimously
agreed that no Substantive Changes1 should be made to the Standard. A straw poll from non‐DT
members in attendance concurred with the DT’s conclusion.

Non-Substantive Changes
The DT is recommending the following Non‐Substantive Changes:

1



Updates to the document template, numbering, and boilerplate sections as provided by NERC



Removal of stale‐dated verbiage included in the Effective Date



Removal of the redundant phrase, “[F]or auditing purposes….” From Measure M4



Updates to syntax



Correction of “[s]tandard” to “[S]tandard”



Correction of “dampen” to “damp” in the Rationale and Guidance section

Definitions, Procedures.

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

Letter to WSC Requesting Information-Only Filing

Standard of Review
Per the WECC Standards Committee (WSC) Charter, the WSC administers the Procedures. Per the
Procedures, each of the above proposed changes is a Non‐Substantive Change2, and does not require a
posting for comment.3 Although the Procedures require a ballot to make Non‐Substantive Changes after
a posting for comment4, the Procedures are silent where a DT recommends only Non‐Substantive
Changes, which require neither a posting nor a ballot.
For guidance, the Procedures provide that if the WSC identifies a Non‐Substantive Change after
comments are received, and/or after a ballot has opened, the “correction shall be filed for approval with
NERC”, as appropriate.5 Further, implementing “updated document styles, templates, or standardized
language…is explicitly within the purview of staff and does not require further approval.”6 Finally, as a
matter of precedence, the WSC has previously accepted a “no change” recommendation regarding a
WECC Criterion that had neither been posted nor balloted.7
In light of the above, the DT requests the WSC exercise its discretion by approving the proposed Non‐
Substantive Changes: 1) without a posting, 2) without a ballot, 3) followed by an information‐only
filing at NERC.

Non‐Substantive Changes, Definitions, Procedures, are those changes: “that do not change the scope,
applicability, or intent of any requirement, including correcting the numbering of a requirement, correcting
references, changes to document styles and templates, correcting the spelling of a word, adding an obviously
missing word, or rephrasing a requirement for improved clarity.”
3 “Non‐Substantive Changes do not require a posting/comment/response cycle.” Treatment of Non‐Substantive
Changes, Procedures, page 12.
4 Treatment of Substantive Changes, Procedures, pages 11‐12.
5 “[T]he WSC agrees that the correction of the error does not change the scope or intent of the associated
[Standard], and agrees that the correction has no material impact on the applicable entities, then the correction
shall be filed for approval with NERC and applicable governmental authorities as appropriate.” Treatment of
Non‐Substantive Changes, Regional Reliability Standards, Procedures, page 12.
6 Procedures, page 12.
7 In December 2016, the WSC approved WECC‐0112, COM‐001‐WECC‐CRT‐2.1, Digital Circuits Synchronization,
a WECC Criterion.
2

2

WECC Standards Committee
Meeting Minutes
December 6, 2022
Virtual

1.

Welcome, Call to Order
James Avery, WECC Standards Committee (WSC) Chair, called the meeting to order at 1:00
p.m. on December 6, 2022. A quorum was established. A list of attendees is attached as Exhibit
A.

2.

Review WECC Antitrust Policy
Steven Rueckert, WECC Director of Standards, read aloud the WECC Antitrust Policy
statement. The meeting agenda included a link to the posted policy.

3.

Approve Agenda
Mr. Avery introduced the proposed meeting agenda.
On a motion by Dana Cabbell, the WSC approved the agenda.

4.

Review and Approve Previous Meeting Minutes
The WSC approved the June 14, 2022, meeting minutes. The WSC did not hold a meeting in
September 2022. A report on the Action Without a Meeting concluding on September 29, 2022,
is included below.
On a motion by Mr. Avery, the WSC approved the minutes.

5.

Review of Previous Action Items
W. Shannon Black reviewed action items carried over from previous meetings of the WSC.


Staff was asked to seek WECC Legal counsel on whether the Western Interconnection
Regional Advisory Body (WIRAB) qualifies for service in Standards Voting Segment
(SVS) 9. Consultation with Chris Albrecht, WECC Legal, concluded that WIRAB does
not meet the criteria for service in SVS 9; however, the WSC recognized the value
provided by WIRAB when networking for that segment. This action is complete.

6.

WECC-0149 Table Revision Project—Request for Ballot
On October 18, 2022, the WECC-0149 Table Revision Process Drafting Team (WECC-0149 DT)
agreed by majority vote to forward the project to the WSC with a request for ballot.

WSC Meeting Minutes December 6, 2022
The project is a continuation of WECC-0141 FAC-501-WECC-3, Transmission Maintenance. The
project is designed to streamline implementation of WECC-0141 by shifting implementation
away from NERC and back to WECC.
On a motion by Mr. Avery, the WSC approved WECC-0149 Table Revision Process for ballot.

7.

WECC-0150—PRC-001-WECC-CRT-3 Governor Droop—SAR Request—
Convene a Drafting Team
On October 18, 2022, Standard Authorization Request (SAR) WECC-0150 PRC-001-WECC-CRT3, Governor Droop, Five-year Review was received and deemed complete.
The SAR can be reviewed on the WECC-0150 on the SAR Form accordion.
The SAR is a request for five-year review per the Procedures. No issues have been identified.
After review, the drafting team is authorized to recommend “no change” if changes are deemed
unnecessary. This document was last reviewed as WECC-0125.
On a motion by Mr. Avery, the WSC approved Standard Authorization Request PRC-001WECC-CRT-3, Governor Droop, Five-year Review.
The WSC instructed staff to solicit a drafting team.

8.

WECC-0148 VAR-501-WECC-4—Power System Stabilizer/No Change—
Information Only Filing
“No Substantive Change"—Informational Filing Only
On June 21, 2022, the WECC-0148 drafting team (WECC-0148 DT) began a five-year review of
VAR-501-WECC-4, Power System Stabilizer, as required by the Procedures.
On July 1, 2022, after reviewing the entire document during multiple public meetings, the DT
unanimously agreed that no Substantive Changes should be made to the Standard.
On July 11, 2022, a list of proposed non-substantive changes was distributed to the Standards
Email List (SEL) inviting comments or concerns to be forwarded to WECC Standards staff. A
redline and a clean version of the project was posted on the WECC-0148, Posted for Comment
accordion. No comments were received.
Non-substantive changes do not require a posting for comment.1

“Non-Substantive Changes do not require a posting/comment/response cycle. Non-Substantive errors
discovered prior to the opening of a WECC ballot on either an RRS or a CRT may be corrected by WECC staff.”
Treatment of Non-Substantive Changes, Procedures, page 12.
1

2

WSC Meeting Minutes December 6, 2022
The WSC was briefed on its procedural authority to approve the project with no further due
process, so long as all changes were deemed non-substantive. (See Attachment A, Request for
Information Filing.)
On a motion by Ms. Cabbell, the WSC accepted WECC-0148 VAR-501-WECC-4 (VAR), Power
System Stabilizer as presented with only non-substantive changes.
The WSC instructed staff to prepare an information-only filing for NERC. Per the Procedures,
no further due process is required for this project.

9.

WECC-0151 INT-007-WECC-CRT-4—Processing of Emergency Requests
for Interchange (RFI)/SAR Approval Recommending No Change
“No Substantive Change”—No Further Action Required
The INT suite of WECC Criteria: 1) was originally drafted by and for the use of the subject
matter experts (SME) of the Interchange Scheduling and Accounting Subcommittee (ISAS).
WECC-0151 is due for a five-year review per the Procedures.
On July 15, 2022, Standards staff requested that WECC Staff Liaison, Layne Brown, ask the ISAS
to review WECC-0151 to determine whether the document required substantive changes.
On August 8, 2022, Danielle Smith (Sacramento Municipal Utility District and chair of the ISAS)
reported to Standards staff that members of the ISAS had reviewed the document and were
recommending that no substantive changes be made.2
The following non-substantive change was requested:


Change the footnote from “See Guidance section” to “See Guidance, under Rationale
section.”

On November 1, 2022, a recommendation of “no substantive change” was dispatched to the SEL
inviting comments or concerns to be forwarded to WECC Standards staff. No comments were
received.
On a motion by Mr. Avery, the WSC accepted WECC-0151 INT-007-WECC-CRT-4—
Processing of Emergency Requests for Interchange (RFI) as presented with only nonsubstantive changes.

The leadership of ISAS reviewed WECC-0151 and WECC-0152. Review included the current and out-going
chair, plus the incoming vice-Chair. After individual review, the cohort held a conference reaching consensus on
the proposed non-substantive changes.
2

3

WSC Meeting Minutes December 6, 2022
This action completes the five-year review required per the Procedures. An updated version of
the WECC Criterion will be published.

10.

WECC-0152 INT-016-WECC-CRT-4—Data Submittal/SAR Approval
Recommending No Change
“No Substantive Change”—No Further Action Required
The INT suite of WECC Criteria: 1) was originally drafted by and for the use of the SMEs of the
ISAS. WECC-0152 is due for a five-year review per the Procedures.
On July 15, 2022, Standards requested that WECC Staff Liaison, Layne Brown, ask the ISAS to
review WECC-0151 to determine whether the document required substantive changes.
On August 8, 2022, Danielle Smith (Sacramento Municipal Utility District and chair of the ISAS)
reported to Standards staff that members of the ISAS had reviewed the document and were
recommending that no substantive changes be made.3
The following non-substantive changes were requested:


In the Rationale section, in the first paragraph of “The Generic use of “Interchange
Software,” replace, “[t]he interchange software currently falls under the purview of Peak
Reliability” with “[t]he interchange software currently falls under the purview of the
ATFWG and under contract with Reliability Coordinator West (RC West).”

On November 1, 2022, a recommendation of “no substantive change” was dispatched to the SEL
inviting comments or concerns to be forwarded to WECC Standards staff. No comments were
received.
On a motion by Mr. Rueckert, the WSC accepted WECC-0152 INT-016-WECC-CRT-4—Data
Submittal as presented with only non-substantive changes.
This action completes the five-year review required per the Procedures. An updated version of
the WECC Criterion will be published.

11.

WECC Glossary of Terms and Naming Conventions—Annual Review
Annual Review—WECC Glossary

The leadership of ISAS reviewed WECC-0150 and WECC-0151. Review included the current and out-going
chair, plus the incoming vice chair. After individual review, the cohort held a conference reaching consensus on
the proposed non-substantive changes.
3

4

WSC Meeting Minutes December 6, 2022
Per the WSC Charter, the WSC is required to annually review the WECC Glossary of Terms and
Naming Conventions (WECC Glossary). The WECC Glossary only contains terms developed
per the Procedures and used in active WECC Criteria.
Because WECC uses NERC’s numbering and naming nomenclature, much of the WECC
Glossary content duplicates that posted on the NERC website. To streamline the document,
redundancies to the NERC website were deleted from the WECC Glossary and replaced with
references to the NERC source documents.
On a motion by Mr. Rueckert, the WSC approved the annual review of the WECC Glossary
of Terms and Naming Conventions, accepting proposed elimination of redundant language
and changing the document name to WECC Glossary of Terms Used in WECC Criteria.

12.

Annual Election of WSC Vice Chair
On December 7, 2021, Gary Nolan was elected as the WSC Vice Chair. On December 6, 2022,
Mr. Nolan was nominated and affirmed to continue in that role. The WSC thanked Mr. Nolan
for his continued dedication to the Standards development process.

13.

WSC Charter and SVS 9 Application
The WSC reviews its charter annually in December.
On March 16, 2022, the WSC concluded that municipal utilities could be included in SVS 9 –
Government. To ensure this finding is applied in future SVS solicitations, staff suggested
adding the following footnote to the WSC Charter, Committee Composition and Governance,
1b. Membership Eligibility:


“On March 16, 2022, the WSC approved municipal utilities for inclusion in SVS 9.”

Although the footnote was approved for addition, later in the March 16, 2022, meeting, the WSC
rescinded that approval opting instead for further discussion informed by a report by WECC
legal counsel.
After further discussion, the WSC concluded that SVS 9 was tailored to include entities not
otherwise subject to the requirements of a Standard/WECC Criterion. This approach provides a
modicum of checks and balances not otherwise afforded by inclusion of municipalities.
Updates were made to the WSC Charter conforming meeting notice and posting requirements
to those currently administered by WECC support staff.
On a motion by Mr. Avery, the WSC approved changes to the WSC Charter as presented.
The revised WSC Charter will be presented to the WECC Board of Directors during the 2023
Annual Meeting.

5

WSC Meeting Minutes December 6, 2022

14.

Reports
Standard Voting Segments—Full Cadre
Mr. Black reported that, on June 30, 2022, and July 19, 2022, WECC dispatched a request for
volunteers to serve in Standard Voting Segments (SVS) 2, 3, 5, 6, and 10 with terms of service
terminating coincident with the close of the WECC Annual Meeting in September 2022.
A single nominee for each SVS was received from each incumbent. Per the WSC Charter, a
ballot was waived, and each nominee was deemed elected. The roster was forwarded to the
WECC Board of Directors for informational purposes.
WECC-0149 DT Change
On July 12, 2022, W. Shannon Black was informed that Christopher Fecke-Stoudt had accepted
employment at Salt River Project and would no longer be serving on the WECC-0149 project.
Six members remain on the team.
WECC-0142 Retire BAL-002-WECC-X Contingency Reserve
The WECC-0142 project has not met for 18 months. Their current task is to create technical
justification for the retirement of BAL-002-WECC-X, Contingency Reserve. The WECC-0142 DT
requested to remain active until it creates an actionable work product.
Mr. Avery asked staff to request the WECC-0142 Drafting Team Chair provide a project update
to the WSC at the March 3, 2023 meeting.

15.

Action Without a Meeting
On September 15, 2022, the WECC-0146, TPL-001-WECC-CRT-3, Transmission System Planning
Performance Drafting Team (DT) forwarded the project to the WSC with a request for ballot.
Because the next duly noticed WSC meeting was not scheduled until December 6, 2022, Mr.
Avery approved an Action Without a Meeting (AWM) per the WSC Charter, for the sole
purpose of approving the project for ballot.
On September 29, 2022, the AWM concluded with unanimous support approving the project for
ballot. Balloting on the project is currently scheduled to conclude on December 16, 2022.

16.

Public Comment
Mr. Avery invited public comment.
Alice Ireland, Proven Compliance Solutions, suggested that a due process procedure should be
discussed to address stalled projects. Ms. Ireland suggested that a self-executing approach to
project termination may not be the best approach. The concept was tabled for further
development at the March 2023 meeting.

6

WSC Meeting Minutes December 6, 2022

17.

Review of New Action Items
Mr. Black reviewed action items carried over from this and previous meetings of the WSC.


WECC-0142
o

Mr. Avery asked staff to request the WECC-0142 Drafting Team Chair provide a
project update to the WSC at the March 3, 2023, meeting. On December 13, 2022,
the request was sent to the WECC-0142 email exploder.



WECC-0148 VAR-501-WECC-4, Power System Stabilizer
o



WECC-0149 Table Revision Project
o



Publish an updated version, no further due process required.

WECC-0152 INT-016-WECC-CRT-4, Data Submittal
o



Solicit a drafting team.

WECC-0151 INT-007-WECC-CRT-4 , Processing of Emergency RFI
o



Ballot the project.

WECC-0150 PRC-001-WECC-CRT-3, Governor Droop
o



Forward an information-only filing to NERC.

Publish an updated version, no further due process required.

WECC Glossary
o

Update and publish the Glossary to include a note explaining that WECC uses
the same naming and numbering nomenclature as that used by NERC.



WSC Charter
o

18.

Update for presentation to the Board in September 2023.

Upcoming Meetings
March 3, 2023, TBD ................................................................................. Salt Lake City, UT
June 13, 20223, TBD ................................................................................. Salt Lake City, UT
December 5, 2023, TBD ........................................................................... Salt Lake City, UT

19.

Adjourn
Mr. Avery adjourned the meeting without objection at 9:40 a.m.

7

WSC Meeting Minutes December 6, 2022

Exhibit A: Attendance List4
Members in Attendance
Matthew Harward, Southwest Power Pool ................................................................................ SVS 2 RTO/ISO
Dana Cabbell, Southern California Edison .......................................................................................... SVS 3 LSE
Gary Nolan, Arizona Public Service (Proxy Jessica Lopez) .................................................SVS 5 Generators 5
Tim Kelley, Sacramento Municipal Utility District ...............................SVS 6 Broker/Aggregator/Marketers
Crystal Musselman, Proven Compliance Solutions (Proxy Alice Ireland) ... SVS 8 Small Electricity Users6
Steven Rueckert, WECC ................................................................................................ SVS 10 Regional Entities
James Avery, Chair .......................................................................................................... Non-Affiliated Director
Members not in Attendance
Ron Sporseen, Bonneville Power Administration .............................................................SVS 1 Transmission
Marty Hostler, Northern California Power Agency..........................................................................SVS 4 TDU
Caitlin Liotiris, Utah Association of Energy Users .................................... SVS 7 Large Electricity End Users
Chris McLean, California Energy Commission ...................................................................SVS 9 Gov. Entities

Terms of Service for SVSs:
Terms of Service for SVSs 1, 4, 7, 8, and 9 conclude at the close of the 2023 WECC Annual Meeting.
Terms of Service for SVSs 2, 3, 5, 6, and 10 conclude at the close of the 2022 WECC Annual Meeting.
5 On December 5, 2022, Mr. Nolan assigned Ms. Jessica Lopez as proxy for the December 6, 2022, meeting.
6 On November 28, 2022, Ms. Musselman assigned Ms. Alice Ireland as proxy for the December 6, 2022, meeting.
4

8

WSC Meeting Minutes December 6, 2022

Attachment A
Request for Information-Only Filing
Recommendation
The WECC-0148 VAR-501-WECC-4 (VAR), Power System Stabilizer, Drafting Team (WECC-0148 DT)
is recommending that no substantive changes be made to the Standard. If the WECC Standards
Committee (WSC) accepts that recommendation, an information-only filing at NERC is recommended. 7

Overview
On May 2, 2016, a WECC Ballot Pool approved VAR-501-WECC-3, Power System Stabilizer, after eight
postings for comment. On April 28, 2017, FERC approved the Standard via letter order followed by
Version 3.1 errata on September 26, 2017. Between 2016 and 2022, no known concerns were raised
regarding the text the of the Standard.
On June 21, 2022, the WECC-0148 DT began a five-year review of the Standard as required by the
Procedures. On July 1, 2022, after reviewing the entire document during multiple public meetings, the
DT unanimously agreed that no Substantive Changes8 should be made to the Standard. This position
was reinforced when the project posted for a 30-day comment period and received zero comments for
consideration.

Non-Substantive Changes
The WECC-0148 DT is recommending the following Non-Substantive changes:






Updates to the template and syntax;
Removal of stale-dated language from the Effective Date;
Deletion of “For auditing purposes of…” from M4;
In the Guidance section:
o

“dampen” was replaced with “damp,”

o

Syntax was addressed deleting “still,” “of those,” “of the,”

o

“[t]o ensure” was replaced with “ensuring,”

o

“[w]ash out” was replaced with “washout.”

If “[t]he WSC agrees that the correction of the error does not change the scope or intent of the associated
[project] and agrees that the correction has no material impact on the applicable entities, then the correction shall
be filed for approval with NERC and applicable governmental authorities as appropriate.” Treatment of NonSubstantive Changes, Regional Reliability Standards, Procedures, page 12.
8 Definitions, Procedures.
7

9

WSC Meeting Minutes December 6, 2022

Standard of Review
Per the WSC Charter, the WSC administers the Procedures. Per the Procedures, each of the proposed
changes is a Non-Substantive change.9 Non-Substantive changes do not require a posting for
comment.10
Additionally, implementing “updated document styles, templates, or standardized language…is
explicitly within the purview of staff and does not require further approval.” 11 Finally, as a matter of
precedence, the WSC has previously accepted a “no change” recommendation regarding a WECC
Criterion that had neither been posted nor balloted. 12
In light of the above, the WEC-0148 DT requests the WSC exercise its discretion by approving the
proposed Non-Substantive Changes: 1) without a posting, 2) without a ballot, 3) followed by an
information-only filing at NERC.

Non-Substantive Changes, Definitions, Procedures, are those changes: “that do not change the scope,
applicability, or intent of any requirement, including correcting the numbering of a requirement, correcting
references, changes to document styles and templates, correcting the spelling of a word, adding an obviously
missing word, or rephrasing a requirement for improved clarity.”
10 “Non-Substantive Changes do not require a posting/comment/response cycle. Non-Substantive errors
discovered prior to the opening of a WECC ballot on either an RRS or a CRT may be corrected by WECC staff.”
Treatment of Non-Substantive Changes, Procedures, page 12.
11 Procedures, page 12.
12 In December 2016, the WSC approved WECC-0112, COM-001-WECC-CRT-2.1, Digital Circuits Synchronization,
a WECC Criterion.
9

10

Type

Title

(1) WECC-0148 VAR-501-WECC-3.1 PSS Info Filing Attachment B -Clean as Approved by NERC
(2) WECC-0148 VAR-501-WECC-4 PSS Info Filing - Attachment A SAR

Modified

2023-07-13
2023-07-13

(3) WECC-0148 VAR-501-WECC-4 PSS Info Filing Attachment E -Project Roadmap

2023-07-13

(4) WECC-0148 VAR-501-WECC-4 PSS Info Filing Attachment D -Redline

2023-07-13

(5) WECC-0148 VAR-501-WECC-4 PSS Info Filing - Attachment C WSC Approved

2023-07-13

(6) WECC-0148 VAR-501-WECC-4 PSS Info Filing Attachment L -Drafting Team Roster

2023-07-13

(7) WECC-0148 VAR-501-WECC-4 PSS Info Filing Attachment T -Additional Supporting Documentation

2023-07-13

(8) WECC-0148 VAR-501-WECC-4 PSS Info Filing - Attachment Q WSC Roster 12-06-2022

2023-07-13

(9) WECC-0148 VAR-501-WECC-4 PSS Info Filing - Attachment J RRS Submittal Request

2023-07-20

(10) WECC-0148 VAR-501-WECC-4 PSS Info Filing - Cover
Letter and Checklist

2023-07-24

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer WECC-0148 Attachment B Clean As Approved by NERC

A. Introduction
1. Title:

Power System Stabilizer (PSS)

2. Number: VAR-501-WECC-3.1
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, that meet the definition of Commercial Operation.
6. Effective Date: The first day of the first quarter following regulatory approval, except
for Requirement R3.
For units placed in first-time service after regulatory approval, Requirement R3 is
effective the first day of the first quarter following final regulatory approval.
For units placed in service prior to final regulatory approval, Requirement R3 is effective
the first day of the first quarter that is five years after regulatory approval.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
• The effective date of this standard;
• The PSS’s Commercial Operation date; or
• Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.

Page 1 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]
•

Component failure

•

Testing of a Bulk Electric System Element affecting or affected by the PSS

•

Maintenance

•

As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:
•

A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.

•

Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter-area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.
Page 2 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.
If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start-up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]
•

The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.

•

The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start-up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
For auditing purposes of Requirement R4, bullet one only applies to equipment on its
initial (first energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority
NERC or the Regional Entity, or any entity as otherwise designated by an
Applicable Governmental Authority, in their respective roles of monitoring and/or
enforcing compliance with mandatory and enforceable Reliability Standards in
their respective jurisdictions.
1.2 Compliance Monitoring and Assessment Processes
•

Compliance Audits

•

Self-Certifications

•

Spot Checking

•

Compliance Investigations

•

Self-Reporting

•

Complaints

1.3 Evidence Retention
The following evidence retention periods identify the period of time an entity is
required to retain specific evidence to demonstrate compliance. For instances
where the evidence retention period specified below is shorter than the time since
the last audit, the Compliance Enforcement Authority may ask an entity to provide
other evidence to show that it was compliant for the full time period since the last
audit.
Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.
1.4 Additional Compliance Information
None

D. Regional Differences
None

Page 4 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

Table of Compliance Elements
R

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

R1

Planning
Horizon

Low

NA

NA

NA

The Generator Owner
failed to provide its PSS
operating specifications
to the Transmission
Operator as required in
Requirement R1.

R2

Operations
Assessment

Medium

Each Generator
Operator not having
its PSS in service while
synchronized in
accordance with
Requirement R2, for
more than 30 minutes
but less than 60
minutes.

Each Generator
Operator not having its
PSS in service while
synchronized in
accordance with
Requirement R2, for
more than 60 minutes
but less than 120
minutes.

Each Generator
Operator not having
its PSS in service while
synchronized in
accordance with
Requirement R2, for
more than 120
minutes but less than
180 minutes.

Each Generator
Operator not having
its PSS in service while
synchronized in
accordance with
Requirement R2, for
more than 180
minutes.

R3

Operations
Assessment

Medium

The Generator
Owner’s PSS failed to
meet any of the
required
performances in
Requirement R3, two
times or fewer during
the audit period.

The Generator Owner’s
PSS failed to meet any
of the required
performances in
Requirement R3, three
times during the audit
period.

The Generator
Owner’s PSS failed to
meet any of the
required performances
in Requirement R3,
four times during the
audit period.

The Generator
Owner’s PSS failed to
meet any of the
required performances
in Requirement R3,
five times or more
during the audit
period.

Page 5 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

R

Time
Horizon

VRF

Violation Severity Levels

R4

Operational
Assessment

Medium

NA

NA

NA

The Generator Owner
failed to install on its
generator a PSS, as
required in
Requirement R4.

R5

Operational
Assessment

Medium

NA

NA

NA

The Generator Owner
failed to repair or
replace a nonoperational PSS as
required in
Requirement R5.

Lower VSL

Moderate VSL

High VSL

Severe VSL

Page 6 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR-STD-002b-1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR501-WECC-1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR-501-WECC-2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR-501-WECC-3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

September 26, 2017

FERC letter order issued
approving VAR-501-WECC-3.1

Change Tracking

Errata

Page 7 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to dampen the low-frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while still allowing for some of these
units to be out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either of the triggering events described in
Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non-active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this standard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this standard while also allowing the Generator Owner to create a unit-specific
operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non-active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator-turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.
The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this standard’s previous version, the logged hours were totaled quarterly to meet the
Page 8 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

98% in-service requirement. Instead of documenting the number of hours excluded, this
Requirement simplifies the process by allowing the Generator Operator to communicate to the
Transmission Operator the circumstances that render the PSS unavailable to the Transmission
Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable wash-out time constants, the Requirement specifies 0.2 Hz
as the applicable threshold. The 0.2 Hz threshold more closely aligns with the observed
oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher-frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed-loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 9 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward to ensure that a unit is tuned,
Requirement R5 looks backward. Specifically, the language in Requirement R5, “becoming
incapable,” indicates the unit was previously capable of meeting the tuning requirements in
Requirement R3, but is no longer capable. Restated, Requirement R5 addresses units that were
previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24-month time frame is sufficient to return a functional, operating PSS to service.

Page 10 of 11

<Public>

VAR-501-WECC-3.1 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR-501-WECC-3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR-501-WECC-3

TBD

TBD

Inactive Date

Page 11 of 11

<Public>

Attachment A
Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Information Only Filing

Overview
This Standard Authorization Request (SAR) was received March 7, 2022, and deemed complete the
same day. The WECC Standards Committee (WSC) vetted this SAR on March 16, 2022.
This SAR can be reviewed on the WECC‐0148 project page at the Standard Authorization Request
accordion. If you have questions regarding this SAR, please contact W. Shannon Black at (503) 307‐
5782.

Introduction
This is a request for five‐year review of WECC Regional Reliability Standard VAR‐501‐WECC‐3.1
Power System Stabilizer.1

Requester Information
Primary contact


First name:

W. Shannon



Last name:

Black



Email:

[email protected]



Phone:

(503) 307‐5782



Organization name:

Western Electricity Coordinating Council (WECC)

Alternate


First name:

Donovan



Last name:

Crane



Email:

[email protected]



Phone:

(801) 883‐6843

Per the WECC Reliability Standards Procedures, Maintenance of RRSs and CRTs: ‘The WSC shall ensure that
each…RRS is reviewed at least once every five years from the effective date of the most recent version of the
document under review. If the review identifies needed changes, the WSC shall cause a remedial SAR to be filed.
If the review does not identify needed changes, no further action is required.”

1

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Five-year Review
Information Only Filing

Type of Request
This is a request for five‐year review of a WECC Regional Reliability Standard.

Create, Modify, Retire or Review a Document
Requested Action (Select one)


This is a request for a five‐year review of a WECC Regional Reliability Standard (RRS).

Document Type (Select one)


WECC Regional Reliability Standard

Issue
This project is assigned WECC Tracking Number WECC‐0148.
This a request for a five‐year review mandated per the WECC Reliability Standards Development
Procedures (Procedures).
Proposed Remedy
This request will review and update the entire document, as needed. No specific concerns have been
identified. The drafting team is authorized to recommend “no change” after reviewing the document.
Applicable Entities
Each function will be reviewed if affected. A dropdown will be provided. Check all applicable blocks.
4. Functional Entities:
4.1. Generator Operator
4.2. Generator Owner
Detailed Description
This request will review and update the entire document, as needed. No specific concerns have been
identified.
Affected Reliability Principles


Reliability Principle 1 — Interconnected bulk power systems shall be planned and operated in
a coordinated manner to perform reliably under normal and abnormal conditions as defined in
the NERC Standards.

2

<Public>

Standard Authorization Request
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Five-year Review
Information Only Filing

Document Information
NA

Reference Uploads
Provide Additional Comments (if needed).
NA

3

<Public>

Attachment E
Project Roadmap
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Informational Only Filing

Project Roadmap

Actions

Completed

1.

Standard Authorization Request (SAR) Filed

March 9, 2022

2.

WECC Standards Committee (WSC) approved the SAR

March 16, 2022

3.

Drafting Team (DT) Solicitation

March 30, 2022

4.

DT Meeting

June 21, 2022

5.

DT Meeting

June 28, 2022

6.

July 11, 2022

8.

Notice to Standard Email List for Proposed Non‐Substantive
Changes – No Substantive Changes Proposed
Posting 1 for Information Only – Comment/Response not
Required
Posting 1 Letter to WSC for Proposed Non‐Substantive Changes

9.

WSC Approved Non‐Substantive Changes

December 6, 2022

10.

WECC Board of Directors—Approved

Not Required

11.

Informational Filing pending at NERC

TBD

12.

NERC Board of Trustees Approves

TBD

7.

July 16, 2022
July 16, 2022

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

A. A.

Attachment D

Introduction

1. Title:

Power System Stabilizer (PSS)

2. Number: VAR‐501‐WECC‐3.14
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, that meetmeeting the definition of Commercial Operation.
6. Effective Date: The first day of the first quarter following regulatory approval, except
for Requirement R3.
For units placed in first‐time service after regulatory approval, Requirement R3 is
effective the first day of the first quarter following final regulatory approval.
For units placed in service prior to final regulatory approval, Requirement R3 is effective
the first day of the first quarter that is five years after regulatory approval.
B.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
 The effective date of this standard;
 The PSS’s Commercial Operation date; or
 Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.

Page 1 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]


Component failure



Testing of a Bulk Electric System Element affecting or affected by the PSS



Maintenance



As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:


A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.



Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter‐area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.

Page 2 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.
If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start‐up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]


The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.



The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start‐up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
For auditing purposes The first bullet of Requirement R4, bullet one only applies to
equipment on its initial (first energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

C. Compliance
C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority
: “Compliance Enforcement Authority” means NERC or the Regional Entity, or any entity
as otherwise designated by an Applicable Governmental Authority, in their
respective roles of monitoring and/or enforcing compliance with mandatory and
enforceable Reliability Standards in their respective jurisdictions.
1.2 Compliance Monitoring and Assessment Processes


Compliance Audits



Self‐Certifications



Spot Checking



Compliance Investigations



Self‐Reporting



Complaints

1.3 . Evidence Retention
: The following evidence retention periodsperiod(s) identify the period of time an entity
is required to retain specific evidence to demonstrate compliance. For instances
where the evidence retention period specified below is shorter than the time since
the last audit, the Compliance Enforcement Authority may ask an entity to provide
other evidence to show that it was compliant for the full ‐time period since the last
audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.


Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.4 Additional Compliance Information
None

D. Regional Differences
None

Page 4 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer
Attachment DB

Table of Compliance Elements
1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 5 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

R1

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

R2

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

R3

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a non‐
operational PSS as required in
Requirement R5.

Page 6 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

Page 7 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Page 8 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR‐STD‐002b‐1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR‐
501‐WECC‐1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR‐501‐WECC‐2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR‐501‐WECC‐3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

TBDSeptember 26,
2017

TBDFERC letter order issued
approving VAR‐501‐WECC‐3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non‐substantive
changes were
approved by the

Page 9 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

an information‐only filing to
NERC.

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information‐only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale‐dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

Page 10 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to dampendamp the low‐frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while still allowing for some of these
units to be out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either of the triggering eventsevent
described in Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non‐active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this
standardStandard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this standardStandard while also allowing the Generator Owner to create a unit‐
specific operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non‐active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator‐turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 11 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this standard’sStandard’s previous version, the logged hours were totaled quarterly
to meet the 98% in‐service requirement. Instead of documenting the number of hours
excluded, this Requirement simplifies the process by allowing the Generator Operator to
communicate to the Transmission Operator the circumstances that render the PSS unavailable
to the Transmission Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable wash‐outwashout time constants, the Requirement
specifies 0.2 Hz as the applicable threshold. The 0.2 Hz threshold more closely aligns with the
observed oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher‐frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed‐loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 12 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward to ensureensuring that a unit is
tuned, Requirement R5 looks backward. Specifically, the language in Requirement R5,
“becoming incapable,” indicates the unit was previously capable of meeting the tuning
requirements in Requirement R3, but is no longer capable. Restated, Requirement R5 addresses
units that were previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24‐month time frame is sufficient to return a functional, operating PSS to service.

Page 13 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR‐501‐WECC‐3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR‐501‐WECC‐3

TBD

TBD

Inactive Date

Page 14 of 14

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

Attachment C

A. Introduction
1. Title:

Power System Stabilizer (PSS)

2. Number: VAR‐501‐WECC‐4
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, meeting the definition of Commercial Operation.
6. Effective Date:

The first day of the first quarter following regulatory approval.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
 The effective date of this standard;
 The PSS’s Commercial Operation date; or
 Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.
For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]


Component failure
Page 1 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer



Testing of a Bulk Electric System Element affecting or affected by the PSS



Maintenance



As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:


A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.



Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter‐area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.
3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.

Page 2 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start‐up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]


The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.



The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start‐up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
The first bullet of Requirement R4 only applies to equipment on its initial (first
energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority: “Compliance Enforcement Authority” means
NERC or the Regional Entity, or any entity as otherwise designated by an
Applicable Governmental Authority, in their respective roles of monitoring and/or
enforcing compliance with mandatory and enforceable Reliability Standards in
their respective jurisdictions.
1.2. Evidence Retention: The following evidence retention period(s) identify the period
of time an entity is required to retain specific evidence to demonstrate
compliance. For instances where the evidence retention period specified below is
shorter than the time since the last audit, the Compliance Enforcement Authority
may ask an entity to provide other evidence to show that it was compliant for the
full‐time period since the last audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.


Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 4 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

R1

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

R2

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

R3

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a non‐
operational PSS as required in
Requirement R5.

Page 5 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR‐STD‐002b‐1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR‐
501‐WECC‐1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR‐501‐WECC‐2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR‐501‐WECC‐3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

September 26, 2017

FERC letter order issued
approving VAR‐501‐WECC‐3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non‐substantive
changes were
approved by the

Page 6 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

an information‐only filing to
NERC.

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information‐only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale‐dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

Page 7 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to damp the low‐frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while allowing for some units to be
out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either triggering event described in
Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non‐active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this Standard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this Standard while also allowing the Generator Owner to create a unit‐specific
operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non‐active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator‐turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 8 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this Standard’s previous version, the logged hours were totaled quarterly to meet
the 98% in‐service requirement. Instead of documenting the number of hours excluded, this
Requirement simplifies the process by allowing the Generator Operator to communicate to the
Transmission Operator the circumstances that render the PSS unavailable to the Transmission
Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable washout time constants, the Requirement specifies 0.2 Hz
as the applicable threshold. The 0.2 Hz threshold more closely aligns with the observed
oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher‐frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed‐loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 9 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward ensuring that a unit is tuned,
Requirement R5 looks backward. Specifically, the language in Requirement R5, “becoming
incapable,” indicates the unit was previously capable of meeting the tuning requirements in
Requirement R3, but is no longer capable. Restated, Requirement R5 addresses units that were
previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24‐month time frame is sufficient to return a functional, operating PSS to service.

Page 10 of 11

<Public>

VAR‐501‐WECC‐4 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR‐501‐WECC‐3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR‐501‐WECC‐3

TBD

TBD

Inactive Date

Page 11 of 11

<Public>

Attachment L
Drafting Team Roster
WECC-0148 VAR-501-WECC-4
Five-year Review

Drafting Team Roster
Below please find a brief biography for each member of the WECC‐0148 VAR‐501‐WECC‐4, Power
System Stabilizer, Five‐year Review Drafting Team.
Name

Qualifications

Greg Anderson,

Mr. Anderson is the subject matter expert for generation and excitation

Southern

systems for the Southern California Edison Company. He has over 33

California Edison

years of experience in the utility industry, with responsibilities for
coordinating WECC testing of generation assets. He has been a WECC
participant since 1997 and a member of the Control Work Group since
2003.

Joel Anthes,
Pacific Gas and
Electric

Mr. Anthes is a Senior Electrical Engineer with Pacific Gas and Electric
Company’s Power Generation organization. Mr. Anthes has more than 16
years of experience in the electrical and power generation industries. Over
the past nine years, he has led the development of multiple technical
programs related to electrical generation and excitation system protection,
control system tuning and modeling, and generator electrical ratings. Mr.
Anthes is a registered professional engineer in the state of California and
plays an active role in the development of industry best practices and
regulatory standards for NERC. Recent experience includes:
•

Member of the drafting team for NERC Project 2020‐02
Transmission‐connected Dynamic Reactive Resources.

•

Power system stabilizer (PSS) tuning and validation.

•

Development of tools for numerical calculation of generator field
current. Performs generator heat runs to prove safe increase of
electrical rating beyond existing nameplate.

•

Development of program for dynamic modeling of generators,
voltage regulators, governors, and power system stabilizers.
Development of associated programs for NERC regulatory
compliance.

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

Attachment L
•

Developed custom tools for determining generator electrical
characteristics, impedances, time constants, phase response, and
capability curves for synchronous generators. Oversees training of
other engineers in the proper implementation of these tools.

•

Commissions and tests excitation systems, voltage regulators, and
power system stabilizers.

•

Performs Root Cause Analyses using industry standard
methodologies for operational safety incidents and major
equipment failures.



Developed recommendations for corrective actions to effectively
prevent the recurrence of equipment failure and human
performance errors.

Shane Kronebusch,
L&S Electric, Inc.

Mr. Kronebusch is the Lead Electrical Engineer and subject matter expert
for generation and excitation systems for L&S Electric, Inc. He has over 31
years of experience in the utility industry, including:


Developing the LS‐AES excitation system.



Designing, installing, and commissioning exciters and governors
across a wide range of units.



Performing of testing and model validation reports for NERC
MOD‐025, ‐026, & ‐027.



Coordinating and preforming WECC testing of generation assets as
an employee of BC Hydro Generation Engineering and
Maintenance Services before joining L&S Electric, Inc. in 2010.



Participating as a member of the WECC Control Work Group since
2006 and drafting team member of WECC‐0099/0107.

Matthew

Mr. McDonald is a Senior Electrical Engineer in the Technical Projects

McDonald, Arizona Engineering department with 15 years of experience in the utility industry.
Public Service

He holds a Bachelor of Science from Pennsylvania State University as well
as a professional engineering license. His expertise and experience include
the following:


13 years’ hands‐on experience installing, troubleshooting,
commissioning, and tuning excitation systems and generator
protection relays.



Five years of experience performing generator, excitation, and PSS
model validation via simulation and live testing.

2

<Public>

Attachment L


Excitation system subject matter expert for Arizona Public Service
for the past four years.



NERC/WECC compliance lead for VAR‐501‐3, PRC‐19‐2, PRC‐002,
PRC‐27‐1 and PRC‐25‐2.



Other responsibilities and roles have included generator excitation
instructor, improvisational field testing, synchro‐phasor and digital
fault recorder commissioning.

Kimberly Turco,

Ms. Turco has worked for Constellation Energy Generation (CEG) for 10

Constellation

years, with the last two years in NERC compliance and supporting ISO

Energy

compliance. CEG is actively involved in NERC’s Standards Under
Development process and would like to take this opportunity for direct
involvement in the review of VAR‐501‐WECC. Kim comes with a wide
background in energy and compliance that would be an asset in the
standards review process.
Kim’s background:


Worked as a subject matter expert in AESO in day‐ahead bidding
and electronic transaction systems (ETS).



Drafted CEG’s Grande Prairie Generation generating station’s
Transmission Must Run Contract.



A barred attorney.



NERC compliance SME and compliance contact for CEG’s WECC
and Alberta generating facilities.



Lead on historical submittal of Automatic Voltage Regulator and
Power System Stabilizer Outage reporting.

Kim has the full support of CEG’s NERC Compliance Group and will be
able to dedicate the time and resources demanded of a member of the
Standards Drafting Team.

3

<Public>

Attachment T
Additional Supporting Documentation
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Non-Substantive Change / Information Only Filing
Letter to WSC Requesting
Information-Only Filing

Preamble
On July 16 2022, the following letter was posted on the WECC‐0148 VAR‐501‐WECC‐4, Power System
Stabilizer home page at the Posting 1 accordion. It was also provided to the WECC Standards
Committee (WSC) for its consideration during the December 6, 2022, WSC meeting.

Recommendation
The WECC‐0148 VAR‐501‐WECC‐4 (VAR), Power System Stabilizer, Drafting Team (DT) is
recommending that no changes be made to the Standard. If the WECC Standards Committee (WSC)
accepts that recommendation, an information‐only filing at NERC is recommended.

Overview
On May 2, 2016, a WECC Ballot Pool approved VAR‐501‐WECC‐3, Power System Stabilizer, after eight
postings for comment. On April 28, 2017, FERC approved the Standard via letter order followed by
Version 3.1 errata on September 26, 2017. Between 2016 and 2022, no known concerns were raised
regarding the text the of the Standard.
On June 21, 2022, the DT began a five‐year review of the Standard as required by the Procedures. On
July 1, 2022, after reviewing the entire document during multiple public meetings, the DT unanimously
agreed that no Substantive Changes1 should be made to the Standard. A straw poll from non‐DT
members in attendance concurred with the DT’s conclusion.

Non-Substantive Changes
The DT is recommending the following Non‐Substantive Changes:

1



Updates to the document template, numbering, and boilerplate sections as provided by NERC



Removal of stale‐dated verbiage included in the Effective Date

Definitions, Procedures.

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

Attachment T
Letter to WSC Requesting Information-Only Filing



Removal of the redundant phrase, “[F]or auditing purposes….” From Measure M4



Updates to syntax



Correction of “[s]tandard” to “[S]tandard”



Correction of “dampen” to “damp” in the Rationale and Guidance section

Standard of Review
Per the WECC Standards Committee (WSC) Charter, the WSC administers the Procedures. Per the
Procedures, each of the above proposed changes is a Non‐Substantive Change2, and does not require a
posting for comment.3 Although the Procedures require a ballot to make Non‐Substantive Changes after
a posting for comment4, the Procedures are silent where a DT recommends only Non‐Substantive
Changes, which require neither a posting nor a ballot.
For guidance, the Procedures provide that if the WSC identifies a Non‐Substantive Change after
comments are received, and/or after a ballot has opened, the “correction shall be filed for approval with
NERC”, as appropriate.5 Further, implementing “updated document styles, templates, or standardized
language…is explicitly within the purview of staff and does not require further approval.”6 Finally, as a
matter of precedence, the WSC has previously accepted a “no change” recommendation regarding a
WECC Criterion that had neither been posted nor balloted.7
In light of the above, the DT requests the WSC exercise its discretion by approving the proposed Non‐
Substantive Changes: 1) without a posting, 2) without a ballot, 3) followed by an information‐only
filing at NERC.

Non‐Substantive Changes, Definitions, Procedures, are those changes: “that do not change the scope,
applicability, or intent of any requirement, including correcting the numbering of a requirement, correcting
references, changes to document styles and templates, correcting the spelling of a word, adding an obviously
missing word, or rephrasing a requirement for improved clarity.”
3 “Non‐Substantive Changes do not require a posting/comment/response cycle.” Treatment of Non‐Substantive
Changes, Procedures, page 12.
4 Treatment of Substantive Changes, Procedures, pages 11‐12.
5 “[T]he WSC agrees that the correction of the error does not change the scope or intent of the associated
[Standard], and agrees that the correction has no material impact on the applicable entities, then the correction
shall be filed for approval with NERC and applicable governmental authorities as appropriate.” Treatment of
Non‐Substantive Changes, Regional Reliability Standards, Procedures, page 12.
6 Procedures, page 12.
7 In December 2016, the WSC approved WECC‐0112, COM‐001‐WECC‐CRT‐2.1, Digital Circuits Synchronization,
a WECC Criterion.
2

2

<Public>

Attachment T
Letter to WSC Requesting Information-Only Filing

Subsequent Entry
On December 6, 2022, the WSC approved the requested Non‐Substantive Changes and instructed staff
to provide NERC with an information‐only filing.

3

<Public>

Attachment Q
WECC Standards Committee Roster
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Non-Substantive Change / Information Only Filing

WECC Standards Committee Roster
The following individuals are those assigned to the WECC Standards Committee as of December 6,
2022.
Ron Sporseen, Bonneville Power Administration ............................................................ SVS 1 Transmission
Matthew Harward, Southwest Power Pool ................................................................................SVS 2 RTO/ISO
Dana Cabbell, Southern California Edison .......................................................................................... SVS 3 LSE
Marty Hostler, Northern California Power Agency ......................................................................... SVS 4 TDU
Gary Nolan, Arizona Public Service ........................................................................................ SVS 5 Generators
Tim Kelley, Sacramento Municipal Utility District .............................. SVS 6 Broker/Aggregator/Marketers
Caitlin Liotiris, Utah Association of Energy Users .................................... SVS 7 Large Electricity End Users
Crystal Musselman, Proven Compliance Solutions .......................................... SVS 8 Small Electricity Users
Chris McLean, California Energy Commission................................................................... SVS 9 Gov. Entities
Steven Rueckert, WECC ................................................................................................ SVS 10 Regional Entities
James Avery, Chair.......................................................................................................... Non‐Affiliated Director

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

Regional Reliability Standard Submittal Request
Attachment J
Region:

Western Electricity Coordinating Council

Regional Standard Number:

VAR‐501‐WECC‐41

Regional Standard Title:

Power System Stabilizer

Date Submitted:

July 20, 2023

Regional Contact Name:

Steven Rueckert

Regional Contact Title:

Director of Standards

Regional Contact Telephone
Number:

(801) 883‐6878

Request (check all that apply):
Retirement of WECC Regional Reliability Standard
Interpret an Existing Standard
Approval of a new standard
Modification of Existing WECC Regional Standard VAR‐501‐WECC‐4 – Information Only
Withdrawal of an existing standard
Urgent Action

Has this action been approved by your Board of Directors:
No
Yes
(If no, please indicate date standard action is expected along with the current status (e.g., third
comment period with anticipated board approval on mm/dd/year)):
Per the WECC Reliability Standards Development Procedures (Procedures), approval of
Non‐Substantive Changes to a Regional Reliability Standard (RRS) do not require WECC
Board of Director (Board) approval.

1

Numbering is subject to NERC assignment.

1
Regional Reliability Standard Submittal Request

<Public>

The WECC Standards Committee (WSC) is empowered by the Procedures to address Non‐
Substantive changes without Board review.
Excerpt from December 6, 2022, WECC Standards Committee minutes:
Item 8:
WECC‐0148 VAR‐501‐WECC‐4 – Power System Stabilizer / No Change – Information Only Filing
“No Substantive Change”‐ Informational Filing Only
On June 21, 2022, the WECC‐0148 drafting team (WECC‐0148 DT) began a five‐year review of VAR‐
501‐WECC‐3.1, Power System Stabilizer, as required by the Procedures.
On July 1, 2022, after reviewing the entire document during multiple public meetings, the DT
unanimously agreed that no Substantive Changes should be made to the Standard.
On July 11, 2022, a list of proposed Non‐Substantive Changes was distributed to the Standards
Email List (SEL) inviting comments or concerns to be forwarded to WECC Standards staff. A redline
and a clean version of the project was posted on the WECC‐0148, Posted for Comment 1
accordion. No comments were received.
Non‐Substantive changes do not require a posting for comment.2
The WSC was briefed on its Procedural authority to approve the project with no further due
process, so long as all changes were deemed Non‐Substantive. (See Attachment A, Request for
Information Filing.)
On a motion by Ms. Cabbell, the WSC accepted WECC‐0148 VAR‐501‐WECC‐4 (VAR), Power
System Stabilizer as presented with only non‐substantive changes.
The WSC instructed staff to prepare an information‐only filing for NERC. Per the Procedures, no
further due process is required for this project.
[Note: The purpose of the remaining questions is to provide NERC with the information needed
to file the regional standard(s) with FERC. The information provided may to a large degree be
used verbatim. It is extremely important for the entity submitting this form to provide sufficient
detail that clearly delineates the scope and justification of the request.]

Not Used.

2

“Non-Substantive Changes do not require a posting/comment/response cycle. Non-Substantive errors discovered prior to
the opening of a WECC ballot on either an RRS or a CRT may be corrected by WECC staff.” Treatment of Non-Substantive
Changes, Procedures, page 12.

2
Regional Reliability Standard Submittal Request

<Public>

Concise statement of the
basis and purpose (scope)
of request:

This request makes Non‐Substantive Changes to VAR‐501‐WECC‐
3.1, Power System Stabilizer.
Non‐Substantive Changes approved by the WECC Standards
Committee (WSC) do not require a Posting/Comment/Response
cycle nor further due process at WECC.
Non‐Substantive Changes were approved by the WSC on December
6, 2022.
This listing of WSC‐approved Non‐Substantive Changes appears in
the VAR‐501‐WECC‐4, Power System Stabilizer Version History
Table:
“An information‐only filing provided to NERC reflects the following:
1) Updates to the template and syntax,
2) Removal of stale‐dated language from the Effective Date,
3) Deletion of “For auditing purposes of…” from M4,
4) In the Guidance section, “dampen” was replaced with “damp”,
and syntax was addressed deleting “still”, “of those”, “of the”, and
“to ensure” was replaced with “ensuring”, and “wash out” was
replaced with “washout.”

Concise statement of the
justification of the
request:

See WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer
Informational Filing – Attachment T – Supporting
Documentation

3
Regional Reliability Standard Submittal Request

<Public>

Steven Rueckert
WECC Director of Standards
July 20, 2023

Ms. Kimberlin Harris
NERC Reliability Standards Department
North American Electric Reliability Corporation
3353 Peachtree Rd. NE, North Tower – Suite 600
Atlanta, GA 30326
Subject:

VAR‐501‐WECC‐4, Power System Stabilizer
Non‐Substantive Changes/Informational Filing Only

Dear Kimberlin,
Per the WECC Reliability Standards Development Procedures (Procedures), the WECC Standards
Committee (WSC) ensures each Regional Reliability Standard undergoes a substantive review at least
once every five years.1
VAR‐501‐WECC‐3, Power System Stabilizer became due for review in September 2022.
On July 1, 2022, after reviewing the entire document during multiple public meetings, a drafting team
of subject matter experts unanimously agreed that no Substantive Changes should be made to the
Standard.2
On July 11, 2022, a list of proposed Non‐Substantive changes was distributed to the WECC Standards
Email List (SEL) inviting comments or concerns to be forwarded to WECC Standards staff regarding
the proposed Non‐Substantive changes.3 No comments were received.
Non‐Substantive changes do not require a posting for comment. Approval of Non‐Substantive changes
is within the purview of the WSC.4

Maintenance of RRSs and CRTs, Procedures, page 21. FERC approved September 13, 2021.
Substantive Change: A change that alters the scope, applicability, required actions, or intent of the document.
Definitions, Procedures, page 3.
3 Non‐Substantive Change: Revisions that do not change the scope, applicability, or intent of any requirement,
including correcting the numbering of a requirement, correcting references, changes to document styles and
templates, correcting the spelling of a word, adding an obviously missing word, or rephrasing a requirement for
improved clarity. Definitions, Procedures, page 3.
4 Treatment of Non‐Substantive Changes, Procedures, page 12.
1
2

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103

<Public>

WECC-0148 VAR-501-WECC-4 – Power System Stabilizer
Non-Substantive Change/Information Only Filing
On December 6, 2022, the WSC approved Non‐Substantive changes to the Standard with instructions
that an information‐only filing be provided to NERC.5
Attached please find:



A redline of the as‐approved Standard showing WSC‐approved Non‐Substantive changes. A
list of the approved changes is included in the version table of the Standard.
A clean version of VAR‐501‐WECC‐4, Power System Stabilizer.

Because the WSC‐approved changes do not affect application of the Standard, an implementation plan
is not needed.
This filing concludes WECC’s required due process per the Procedures. Please update the NERC‐
controlled version of the Standard.
If you have questions, please feel free to contact me.

Sincerely,
Steven Rueckert
WECC Director of Standards

5

Loc. Cit. See also WSC Minutes for December 6, 2022.

2

<Public>

WECC-0148 VAR-501-WECC-4 – Power System Stabilizer
Non-Substantive Change/Information Only Filing
For documentation support, please contact W. Shannon Black at (503) 307‐5782.

WECC‐0148 VAR‐501‐WECC‐4 – Power System Stabilizer / No Change –
Information Only Filing

QR

BOT

Gov’t
Auth.*

SAR – Standard Authorization Request Attachment A
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment A
SAR
Regional Reliability Standard(s) (Clean Existing) Attachment B
File Name: WECC‐0148 VAR‐501‐WECC‐3.1 Power System Stabilizer Informational Filing ‐ Attachment
B ‐ Clean as Approved by NERC
Regional Reliability Standard(s) (Clean Proposed) Attachment C
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment C
– WSC Approved
Regional Reliability Standard(s) (Existing redlined to Proposed)
Attachment D
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing‐ Attachment D
– Redline
Project Roadmap Attachment E
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing‐ Attachment E
Project Roadmap
Implementation Plan Attachment F
File Name: Not Used
Technical Justification Attachment G
File Name: Not Used
VRF & VSL Justification Attachment H
File Name: Not Used
Issue Table and Mapping Document Attachment I – Optional
File Name: Not Used

3

<Public>

WECC-0148 VAR-501-WECC-4 – Power System Stabilizer
Non-Substantive Change/Information Only Filing
Regional Reliability Standard Submittal Request Attachment J
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment J
Regional Reliability Standard Submittal Request
Order 672 Criteria Attachment K
File Name: Not Used
Drafting Team Roster with Biographies Attachment L
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment L ‐
Drafting Team Roster
Ballot Pool Members Attachment M
File Name: Not Used
Final Ballot Results Attachment N
File Name: Not Used
Guidance Document Attachment O – Optional
File Name: Not Used
Minority Issues Attachment P
File Name: Not Used
WECC Standards Committee Roster Attachment Q
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment Q
– WSC Roster 12‐06‐2022
Responses to Comments – WECC Attachment R
File Name: Not Used
FERC Issues Table Attachment S – Optional
File Name: Not Used
Additional Supporting Documentation Attachment T
File Name: WECC‐0148 VAR‐501‐WECC‐4 Power System Stabilizer Informational Filing ‐ Attachment T
– Supporting Documentation
Petition Filing (FERC) Attachment U – Optional

4

<Public>

WECC-0148 VAR-501-WECC-4 – Power System Stabilizer
Non-Substantive Change/Information Only Filing
File Name: Not Used
*Applicable governmental authorities in the United States, Canada, and Mexico
To be provided by NERC.

5

​
​

(4) Unofficial Comment Form (Word)
(5) Submit Comments
(6) Comments Received
​

Regional Reliability Standards
Announcement

Western Electricity Coordinating Council
VAR-501-WECC-4
Comment Period Open through September 29, 2023
Now Available

Western Electricity Coordinating Council (WECC) requested that NERC post Regional Reliability
Standard VAR-501-WECC-4 (Power System Stabilizer) for industry review and comment in accordance
with the NERC Rules of Procedure.
Background

Proposed Regional Reliability Standard VAR-501-WECC-4 – Power System Stabilizer modifies the currently
effective regional standard VAR-501-WECC-3.1 as follows:
•

Updates to the document template, numbering, and template sections as provided by NERC

•

Removal of stale-dated verbiage included in the Effective Date

•

Removal of the redundant phrase, “[F]or auditing purposes….” From Measure M4

•

Updates to syntax

•

Correction of “[s]tandard” to “[S]tandard”

•

Correction of “dampen” to “damp” in the Rationale and Guidance section

The WECC Board of Directors approved the proposed regional standard on June 14, 2023.
Commenting

Use the Standards Balloting and Commenting System (SBS) to submit comments. Comments must be
submitted by 8 p.m. Eastern, Friday, September 29, 2023. An unofficial Word version of the comment
form is posted on the Regional Reliability Standards Under Development page.
•

Contact NERC IT support directly at https://support.nerc.net/ (Monday – Friday, 8 a.m. - 5 p.m.
Eastern) for problems regarding accessing the SBS due to a forgotten password, incorrect
credential error messages, or system lock-out.

•

Passwords expire every 6 months and must be reset.

•

The SBS is not supported for use on mobile devices.

RELIABILITY | RESILIENCE | SECURITY

•

Please be mindful of ballot and comment period closing dates. We ask to allow at least 48 hours
for NERC support staff to assist with inquiries. Therefore, it is recommended that users try logging
into their SBS accounts prior to the last day of a comment/ballot period.

Regional Reliability Standards Development Process

Section 300 of NERC’s Rules of Procedures of the Electric Reliability Organization governs the regional
reliability standards development process. Although the technical aspects of this Regional Reliability
Standard have been vetted through WECC Regional Standards development process, the final approval
process for a Regional Reliability Standard requires NERC publicly to notice and request comment on the
criteria outlined in the unofficial comment form.
Documents and information about this project are available on the Western Electricity Coordinating
Council (WECC) Standards page.
For more information or assistance, contact Reliability Standards Analyst, Kimberlin Harris (via email) or at
(404) 446-9794.
North American Electric Reliability Corporation
3353 Peachtree Rd, NE
Suite 600, North Tower
Atlanta, GA 30326
404-446-2560 | www.nerc.com

Regional Reliability Standards Announcement
VAR-501-WECC-4 | August 16 – September 29, 2023

2

VAR-501-WECC-4 – Power System Stabilizer

Attachment C

A. Introduction
1. Title:

Power System Stabilizer (PSS)

2. Number: VAR-501-WECC-4
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, meeting the definition of Commercial Operation.
6. Effective Date:

The first day of the first quarter following regulatory approval.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
• The effective date of this standard;
• The PSS’s Commercial Operation date; or
• Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.
For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]
•

Component failure
Page 1 of 11

VAR-501-WECC-4 – Power System Stabilizer

•

Testing of a Bulk Electric System Element affecting or affected by the PSS

•

Maintenance

•

As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:
•

A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.

•

Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter-area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.
3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.

Page 2 of 11

VAR-501-WECC-4 – Power System Stabilizer

If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start-up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]
•

The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.

•

The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start-up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
The first bullet of Requirement R4 only applies to equipment on its initial (first
energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 11

VAR-501-WECC-4 – Power System Stabilizer

C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority: “Compliance Enforcement Authority” means
NERC or the Regional Entity, or any entity as otherwise designated by an
Applicable Governmental Authority, in their respective roles of monitoring and/or
enforcing compliance with mandatory and enforceable Reliability Standards in
their respective jurisdictions.
1.2. Evidence Retention: The following evidence retention period(s) identify the period
of time an entity is required to retain specific evidence to demonstrate
compliance. For instances where the evidence retention period specified below is
shorter than the time since the last audit, the Compliance Enforcement Authority
may ask an entity to provide other evidence to show that it was compliant for the
full-time period since the last audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.
•

Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 4 of 11

VAR-501-WECC-4 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

R1

Moderate VSL

High VSL

Severe VSL

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a nonoperational PSS as required in
Requirement R5.

R2

R3

Page 5 of 11

VAR-501-WECC-4 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR-STD-002b-1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR501-WECC-1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR-501-WECC-2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR-501-WECC-3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

September 26, 2017

FERC letter order issued
approving VAR-501-WECC-3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non-substantive
changes were
approved by the

Page 6 of 11

VAR-501-WECC-4 – Power System Stabilizer

an information-only filing to
NERC.

4

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information-only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale-dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

TBD

Page 7 of 11

VAR-501-WECC-4 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to damp the low-frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while allowing for some units to be
out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either triggering event described in
Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non-active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this Standard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this Standard while also allowing the Generator Owner to create a unit-specific
operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non-active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator-turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 8 of 11

VAR-501-WECC-4 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this Standard’s previous version, the logged hours were totaled quarterly to meet
the 98% in-service requirement. Instead of documenting the number of hours excluded, this
Requirement simplifies the process by allowing the Generator Operator to communicate to the
Transmission Operator the circumstances that render the PSS unavailable to the Transmission
Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable washout time constants, the Requirement specifies 0.2 Hz
as the applicable threshold. The 0.2 Hz threshold more closely aligns with the observed
oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher-frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed-loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 9 of 11

VAR-501-WECC-4 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward ensuring that a unit is tuned,
Requirement R5 looks backward. Specifically, the language in Requirement R5, “becoming
incapable,” indicates the unit was previously capable of meeting the tuning requirements in
Requirement R3, but is no longer capable. Restated, Requirement R5 addresses units that were
previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24-month time frame is sufficient to return a functional, operating PSS to service.

Page 10 of 11

VAR-501-WECC-4 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR-501-WECC-3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR-501-WECC-3

TBD

TBD

Inactive Date

Page 11 of 11

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

A. A.

Attachment D

Introduction

1. Title:

Power System Stabilizer (PSS)

2. Number: VAR‐501‐WECC‐3.14
3. Purpose: To ensure the Western Interconnection is operated in a coordinated manner
under normal and abnormal conditions by establishing the performance criteria for
WECC power system stabilizers.
4. Applicability:
4.1

Generator Operator

4.2 Generator Owner
5. Facilities: This standard applies to synchronous generators, connected to the Bulk
Electric System, that meetmeeting the definition of Commercial Operation.
6. Effective Date: The first day of the first quarter following regulatory approval, except
for Requirement R3.
For units placed in first‐time service after regulatory approval, Requirement R3 is
effective the first day of the first quarter following final regulatory approval.
For units placed in service prior to final regulatory approval, Requirement R3 is effective
the first day of the first quarter that is five years after regulatory approval.
B.

B. Requirements and Measures
R1. Each Generator Owner shall provide to its Transmission Operator, the Generator
Owner’s written Operating Procedure or other document(s) describing those known
circumstances during which the Generator Owner’s PSS will not be providing an active
signal to the Automatic Voltage Regulator (AVR), within 180 days of any of the
following events: [Violation Risk Factor: Low] [Time Horizon: Planning Horizon]
 The effective date of this standard;
 The PSS’s Commercial Operation date; or
 Any changes to the PSS operating specifications.
M1. Each Generator Owner will have documented evidence that it provided to its
Transmission Operator, within the time allotted as described in the procedures
required under Requirement R1, written Operating Procedures or other document(s)
describing those known circumstances during which the Generator Owner’s PSS will
not be providing an active signal to the AVR.
For auditing purposes, because Requirement R1 conditions are intended to be
unchanged unless the Transmission Operator is otherwise notified, the Generator
Owner only needs to provide the documentation to the Transmission Operator one
time, or whenever the operating specifications change.

Page 1 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

For auditing purposes, if a PSS is in service but is not providing an active signal to the
AVR as described in Requirement R1, the disabled period does not count against the
Requirement R2 mandate to be in service except as otherwise allowed.
R2. Each Generator Operator shall have its PSS in service while synchronized, except
during any of the following: [Violation Risk Factor: Medium] [Time Horizon: Operating
Assessment]


Component failure



Testing of a Bulk Electric System Element affecting or affected by the PSS



Maintenance



As agreed upon by the Generator Operator and the Transmission Operator

A PSS that is out of service for less than 30 minutes does not create a violation
of this Requirement, regardless of cause.
M2. Each Generator Operator will have documentation of each claimed exception
specified in Requirement R2. Documentation may include, but is not limited to:


A written explanation covering the bulleted exception that describes the
circumstances of the exception as allowed in Requirement R2.



Documented evidence that the Generator Operator and the Transmission
Operator agreed the PSS would not be operating during a specified set of
circumstances, where the exception is claimed under the last bullet of
Requirement R2.

For auditing purposes, the presumption is that the PSS was in service unless otherwise
exempted in Requirement R2. Evidence need only be provided to prove the
circumstances during which the PSS was not in service for periods in excess of 30
minutes.
R3. Each Generator Owner shall tune its PSS to meet the following inter‐area mode
criteria, except as specified in Requirement R3, Part 3.5 below: [Violation Risk Factor:
Medium] [Time Horizon: Operating Assessment]
3.1. PSS shall be set to provide the measured, simulated, or calculated compensated
Vt/Vref frequency response of the excitation system and synchronous machine
such that the phase angle will not exceed ± 30 degrees through the frequency
range from 0.2 Hertz to the lesser of 1.0 Hertz or the highest frequency at which
the phase of the Vt/Vref frequency response does not exceed 90 degrees.
3.2. PSS output limits shall be set to provide at least ±5% of the synchronous
machine’s nominal terminal voltage.
3.3. PSS gain shall be set to between 1/3 and 1/2 of maximum practical gain.
3.4. PSS washout time constant shall be no greater than 30 seconds.

Page 2 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

3.5. Units that have an excitation system or PSS that is incapable of meeting the
tuning requirements of Requirement R3 are exempt from Requirement R3 until
the voltage regulator is either replaced or retrofitted such that the PSS becomes
capable of meeting the tuning requirements.
M3. Each Generator Owner will have documented evidence that its PSS was tuned to
meet the specifications of Requirement R3.
If the exception under Requirement R3, Part 3.5, is claimed, the Generator Owner will
have documented evidence describing: 1) the conditions that render the PSS incapable
of meeting the tuning requirements, and 2) the date the voltage regulator was last
replaced or retrofitted.
R4. Each Generator Owner shall install and complete start‐up testing of a PSS on its
generator within 180 days of either of the following events: [Violation Risk Factor:
Medium] [Time Horizon: Operational Assessment]


The Generator Owner connects a generator to the BES, after achieving
Commercial Operation, and after the Effective Date of this standard.



The Generator Owner replaces the voltage regulator on its existing excitation
system, after achieving Commercial Operation for its generator that is
connected to the BES, and after the Effective Date of this standard.

M4. Each Generator Owner will have evidence that it installed and completed start‐up
testing of a PSS on its generator within 180 days of either of the conditions described
in Requirement R4, and when those conditions occur after the Effective Date of this
standard.
For auditing purposes The first bullet of Requirement R4, bullet one only applies to
equipment on its initial (first energization) connection to the BES.
R5. Each Generator Owner shall repair or replace a PSS within 24 months of that PSS
becoming incapable of meeting the tuning specifications stated in Requirement R3.
[Violation Risk Factor: Medium] [Time Horizon: Operational Assessment]
M5. Each Generator Owner will have evidence that it repaired or replaced its PSS within
24 months of that PSS becoming incapable of meeting the tuning specifications of
Requirement R3. Evidence may include, but is not limited to, documentation of the
date the PSS became incapable of meeting the Requirement R3 tuning specifications,
and the date the PSS was returned to service, demonstrating that the span of time
between the two events was less than 24 months.

Page 3 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

C. Compliance
C. Compliance
1. Compliance Monitoring Process
1.1 Compliance Enforcement Authority
: “Compliance Enforcement Authority” means NERC or the Regional Entity, or any entity
as otherwise designated by an Applicable Governmental Authority, in their
respective roles of monitoring and/or enforcing compliance with mandatory and
enforceable Reliability Standards in their respective jurisdictions.
1.2 Compliance Monitoring and Assessment Processes


Compliance Audits



Self‐Certifications



Spot Checking



Compliance Investigations



Self‐Reporting



Complaints

1.3 . Evidence Retention
: The following evidence retention periodsperiod(s) identify the period of time an entity
is required to retain specific evidence to demonstrate compliance. For instances
where the evidence retention period specified below is shorter than the time since
the last audit, the Compliance Enforcement Authority may ask an entity to provide
other evidence to show that it was compliant for the full ‐time period since the last
audit.
The applicable entity shall keep data or evidence to show compliance as identified
below unless directed by its Compliance Enforcement Authority to retain specific
evidence for a longer period of time as part of an investigation.


Each Generator Operator shall keep evidence for all Requirements of the
document for a period of three years plus calendar current.

1.4 Additional Compliance Information
None

D. Regional Differences
None

Page 4 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer
Attachment DB

Table of Compliance Elements
1.3 Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of
Procedure, “Compliance Monitoring and Enforcement Program” refers to the
identification of the processes that will be used to evaluate data or information for
the purpose of assessing performance or outcomes with the associated Reliability
Standard.

Page 5 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

R

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

R1

NA

NA

NA

The Generator Owner failed to
provide its PSS operating
specifications to the
Transmission Operator as
required in Requirement R1.

R2

Each Generator Operator not
having its PSS in service while
synchronized in accordance with
Requirement R2, for more than 30
minutes but less than 60 minutes.

Each Generator Operator
not having its PSS in service
while synchronized in
accordance with
Requirement R2, for more
than 60 minutes but less
than 120 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 120 minutes but
less than 180 minutes.

Each Generator Operator not
having its PSS in service while
synchronized in accordance
with Requirement R2, for
more than 180 minutes.

R3

The Generator Owner’s PSS failed
to meet any of the required
performances in Requirement R3,
two times or fewer during the
audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, three times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, four times
during the audit period.

The Generator Owner’s PSS
failed to meet any of the
required performances in
Requirement R3, five times or
more during the audit period.

R4

NA

NA

NA

The Generator Owner failed to
install on its generator a PSS,
as required in Requirement R4.

R5

NA

NA

NA

The Generator Owner failed to
repair or replace a non‐
operational PSS as required in
Requirement R5.

Page 6 of 14

<Public>

VAR‐501‐WECC‐43.1 – Power System Stabilizer

Page 7 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Page 8 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

D. Regional Variances
None.

E. Associated Documents
None.

Version History
Version

Date

Action

1

April 16, 2008

Permanent Replacement
Standard for VAR‐STD‐002b‐1

1

October 28, 2008

Adopted by NERC Board of
Trustees

1

April 21, 2011

FERC Order issued approving
VAR‐
501‐WECC‐1 (FERC approval
effective June 27, 2011;
Effective Date July 1, 2011)

2

November 13, 2014

Adopted by NERC Board of
Trustees

2

March 3, 2015

FERC letter order approved
VAR‐501‐WECC‐2

3

February 9, 2017

Adopted by NERC Board of
Trustees

3

April 28, 2017

FERC letter order approved
VAR‐501‐WECC‐3

3.1

August 10, 2017

Adopted by the NERC Board of
Trustees

3.1

TBDSeptember 26,
2017

TBDFERC letter order issued
approving VAR‐501‐WECC‐3.1

4

December 6, 2022

WECC Standards Committee
accepted a “no change “
recommendation followed by

Change Tracking

Errata

Non‐substantive
changes were
approved by the

Page 9 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

an information‐only filing to
NERC.

WECC Standards
Committee as
allowed in the WECC
Reliability Standards
Development
Procedures. An
information‐only
filing provided to
NERC reflects the
following: 1) updates
to the template and
syntax, 2) removal of
stale‐dated language
from the Effective
Date, 3) deletion of
“For auditing
purposes of…” from
M4, 4) in the
Guidance section,
“dampen” was
replaced with
“damp”, and syntax
was addressed
deleting “still”, “of
those”, “of the”, and
“to ensure” was
replaced with
“ensuring”, and
“wash out” was
replaced with
“washout.”

Page 10 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Guideline and Technical Basis
PSS systems are used to minimize real power oscillations by rapidly adjusting the field of the
generator to dampendamp the low‐frequency oscillations.
It is necessary for large numbers of PSS devices to be in operation in the Western
Interconnection to provide the required system damping while still allowing for some of these
units to be out of service whenever necessary.
Mandate to Install a PSS
Nothing in this Regional Reliability Standard (RSS) should be construed to require installation of
a PSS solely because a PSS is not currently installed as of the Effective Date of this RRS. Rather,
installation is only mandated on the occurrence of either of the triggering eventsevent
described in Requirement R4, Bullet 1 or Bullet 2, after the Effective Date of the RRS.
It should be noted that a PSS is neither Transmission nor generation.
Requirement R1
Requirement R1 addresses normal operating conditions.
Requirement R1 recognizes that PSS systems have varying states, such as on, off, active, and
non‐active. As long as the PSS is operating in accordance with the documentation provided to
the Transmission Operator, this is not considered a status change for purposes of this
standardStandard.
This Requirement eliminates the requirement to count hours as required in the previous
version of this standardStandard while also allowing the Generator Owner to create a unit‐
specific operating plan.
The intent of Requirement R1 is to provide the Transmission Operator, the PSS operating zone
in which the PSS is “active” providing damping to the power system. Some PSS may be
programmed to become “active” at a specified megawatt loading level and above while others
may be programmed to be “active” in a particular band of megawatt loading levels and are
“non‐active” only when passing through the “rough zone” or some other band. A “rough zone”
is a megawatt loading band in which the generator‐turbine system could contribute to system
instability.
Requirement R2
This Requirement only applies when the PSS is out of service for a period greater than 30
minutes.
Unlike Requirement R1, Requirement R2 addresses exceptions to normal operation.

Page 11 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

The intent of Requirement R2 is to remove the previous requirement to log hours for PSS in
service. In this standard’sStandard’s previous version, the logged hours were totaled quarterly
to meet the 98% in‐service requirement. Instead of documenting the number of hours
excluded, this Requirement simplifies the process by allowing the Generator Operator to
communicate to the Transmission Operator the circumstances that render the PSS unavailable
to the Transmission Operator (such as component failure, maintenance, and testing).
Requirement R3
Nothing in this RSS should be construed to mandate the design criteria for the equipment used
to produce the tuning output of the PSS. Rather, Requirement R3 is intended to address the
design criteria for the tuning output of the PSS.
Unlike the language in Requirement R5 that looks backward to address units that were once
operating but are no longer capable of operating, Requirement R3 looks forward, requiring that
units be tuned to the specified parameters.
The PSS transfer function should compensate the phase characteristics of the generator,
exciter, and power (GEP) system transfer function so the compensated transfer function
((PSS(s) * GEP(s)) has a phase characteristic of ± 30 degrees in the frequency range.
The GEP(s) transfer function is a theoretical transfer function, and its phase characteristic
cannot be directly measured during field tests (only via simulation). Thus, the Requirement
recognizes the practical approach of measuring the frequency response between voltage
reference set point and terminal voltage (Et/Vref) and using the phase characteristic of such
frequency response as being the phase characteristic of GEP(s). The phase characteristic of
Et/Vref is a better approximation to the phase characteristic of GEP(s) when the frequency
response Et/Vref is obtained with the generator synchronized to the grid at its minimum stable
power output.
In an effort to allow for reasonable wash‐outwashout time constants, the Requirement
specifies 0.2 Hz as the applicable threshold. The 0.2 Hz threshold more closely aligns with the
observed oscillation frequencies.
A properly tuned PSS should provide positive damping to the local mode of oscillation, which
typically has a frequency higher than 1.0 Hz.
This Requirement modifies the requirement associated with the adjustment of the PSS gain.
The standard no longer defines the PSS gain in terms of gain margin but instead requires the
final PSS gain to be between 1/3 (10 dB) and 1/2 (6 dB) of the maximum practical gain that
could be achieved during PSS commissioning. The maximum practical gain might be associated
with the excessive noise or raised higher‐frequency oscillations in the closed loop response
(exciter mode) or any other form if there is inadequate closed‐loop performance, as
determined during PSS commissioning. It is now part of Measure M3 to show the field test
results that led to the determination of the maximum practical gain.

Page 12 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

Requirement R4
Requirement R4 requires a Generator Owner to install a PSS on new applicable units or when
excitation systems are replaced or retrofitted on existing applicable units. This Requirement
applies to new excitation systems and not to existing systems that do not have PSS. The
Requirement also allows a reasonable amount of time for the commissioning of new PSS.
Requirement R5
Unlike the language in Requirement R3 that looks forward to ensureensuring that a unit is
tuned, Requirement R5 looks backward. Specifically, the language in Requirement R5,
“becoming incapable,” indicates the unit was previously capable of meeting the tuning
requirements in Requirement R3, but is no longer capable. Restated, Requirement R5 addresses
units that were previously working but are now no longer working.
The intent of Requirement R5 is to remove the “tiered” approach to PSS repair/replacement
following a failure. A simple, streamlined approach to allow the Generator Owner sufficient
time to repair or replace a broken PSS has been written. Consideration has been given for the
need to procure parts or new equipment, schedule an equipment/unit outage, and install and
test the repaired or replaced PSS. It is recognized that in some instances, it may require
(1) replacement of an AVR, and (2) the existence of a PSS, or both the AVR and the PSS may
need to be replaced to achieve a functioning system.
The 24‐month time frame is sufficient to return a functional, operating PSS to service.

Page 13 of 14

<Public>

VAR‐501‐WECC‐3.14 – Power System Stabilizer

* FOR INFORMATIONAL PURPOSES ONLY *
Enforcement Dates: Standard VAR‐501‐WECC‐3 — Power System Stabilizer
United States
Standard

Requirement

Enforcement Date

VAR‐501‐WECC‐3

TBD

TBD

Inactive Date

Page 14 of 14

Unofficial Comment Form
Regional Reliability Standard
VAR-501-WECC-4

DO NOT use this form for submitting comments. Use the electronic form to submit comments on the
proposed modifications to Regional Reliability Standard, VAR-501-WECC-4 (Power System Stabilizer).
The electronic form must be submitted by 8 p.m. Eastern, Friday, September 29, 2023.
Documents and information about this project are available on the WECC’s Standards page. If you have
questions, contact Reliability Standards Analyst, Kimberlin Harris (via email) or at (404) 446-9794.
Background Information

The WECC Regional Reliability Standard Drafting Team ensures each Regional Reliability Standard
undergoes a substantive review at least once every five years. During the most recent review, the
following changes to WECC’s Regional Reliability Standard VAR-501-WECC-3.1 Power System Stabilizer
were proposed:
1. Updates to the document template, numbering, and template sections as provided by NERC
2. Removal of stale-dated verbiage included in the Effective Date
3. Removal of the redundant phrase, “[F]or auditing purposes….” From Measure M4
4. Updates to syntax
5. Correction of “[s]tandard” to “[S]tandard”
6. Correction of “dampen” to “damp” in the Rationale and Guidance section
The WECC Board of Directors approved the proposed regional standard on June 14, 2023.
NERC Criteria for Developing or Modifying a Regional Reliability Standard

Each regional difference (i.e. Regional Reliability Standard or Variance) shall be: (1) is more stringent than
the continent-wide Reliability Standard, including a regional difference that addresses matters that the
continent-wide reliability standard does not; or (2) necessitated by a physical difference in the bulk power
system. Regional Reliability Standards and Variances shall provide for as much uniformity as possible with
Reliability Standards across the interconnected bulk power system of the North American continent.
Regional Reliability Standards and Variances, when approved by FERC and applicable authorities in Mexico
and Canada, shall be made part of the body of NERC Reliability Standards and shall be enforced upon all
applicable Bulk Power System owners, operators, and users within the applicable area, regardless of
membership in the region.
The approval process for a proposed Regional Reliability Standard or Variance, or the retirement of an
existing standard or Variance, requires NERC to publicly notice and request comment. Comments shall be

RELIABILITY | RESILIENCE | SECURITY

permitted only on the following criteria (technical aspects of the standard are vetted through the regional
standards development process):
Unfair or Closed Process – The Regional Reliability Standard was not developed in a fair and open process
that provided an opportunity for all interested parties to participate. Although a NERC-approved Regional
Reliability Standards development procedure shall be presumed to be fair and open, objections could be
raised regarding the implementation of the procedure.
Adverse Reliability or Commercial Impact on Other Interconnections – The Regional Reliability Standard
would have a significant adverse impact on reliability or commerce in other interconnections.
Deficient Standard – The Regional Reliability Standard fails to provide a level of reliability of the Bulk
Power System such that the Regional Reliability Standard would be likely to cause a serious and
substantial threat to public health, safety, welfare, or national security.
Adverse Impact on Competitive Markets within the Interconnection – The Regional Reliability Standard
would create a serious and substantial burden on competitive markets within the interconnection that is
not necessary for reliability.
Questions

1. Do you agree the proposed Regional Reliability Standard was developed in a fair and open process,
using the associated Regional Reliability Standards Development Procedure?
Yes
No
Comments:
2. Does the proposed Regional Reliability Standard pose an adverse impact to reliability or commerce
in a neighboring region or interconnection?
Yes
No
Comments:
3. Does the proposed Regional Reliability Standard pose a serious and substantial threat to public
health, safety, welfare, or national security?
Yes
No
Comments:

Unofficial Comment Form
VAR-501-WECC-4 | August 16-September 29, 2023

2

4. Does the proposed Regional Reliability Standard pose a serious and substantial burden on
competitive markets within the interconnection that is not necessary for reliability?
Yes
No
Comments:
5. Does the proposed Regional Reliability Standard meet at least one of the following criteria?
•

The proposed Regional Reliability Standard has more specific criteria for the same
requirements covered in a continent-wide standard.

•

The proposed Regional Reliability Standard has requirements that are not included in the
corresponding continent-wide standard.

•

The proposed regional difference is necessitated by a physical difference in the Bulk Power
System.
Yes
No

Comments:

Unofficial Comment Form
VAR-501-WECC-4 | August 16-September 29, 2023

3

NERC Balloting Tool (/)

Dashboard (/)

Users

Ballots

Comment Forms
Login (/Users/Login) / Register (/Users/Register)

REAL-TIME COMMENTS
This comment form is no longer interactive because the comment period is closed.

Regional Reliability Standard (WECC) | VAR-501-WECC-4 – Power System
Stabilizer
Description:
Start Date: 08/16/2023
End Date: 09/29/2023
Associated Ballots:
Ballot Name

Filter:

Project

Standard

None

Pool Open

Pool Close

Voting Start

Voting End

Filter

 Q:
1. Do you agree the proposed Regional Reliability Standard was developed in a fair and open process,
using the associated Regional Reliability Standards Development Procedure?

Hot Answers

 A: Yes (.a-b-78564)
Israel Perez, On Behalf of: Salt River Project - WECC - Segments 1, 3, 5, 6
 -0 -0

 A: Yes (.a-b-78559)
ACES Collaborators, Segment(s) 1, 9/29/2023
 -0 -0

Other Answers

 A: Yes (.a-b-78351)
BC Hydro, Segment(s) 3, 5, 1, 12/18/2018
 -0 -0

 A: Yes (.a-b-78356)
Andrea
On Behalf
of: Bonneville
Power Administration, WECC, Segments 1, 5, 6
© 2023 - NERC
VerJessup,
4.2.1.0 Machine
Name:
ERODVSBSWB01

 -0 -0

 A: Yes (.a-b-78370)
Robert Follini, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: Yes (.a-b-78380)
Glen Farmer, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: Yes (.a-b-78445)
Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5
 -0 -0

 A: Yes (.a-b-78526)

None
Daniela Atanasovski, On Behalf of: APS - Arizona Public Service Co., , Segments 1, 3, 5, 6
 -0 -0

 A: Yes (.a-b-78549)
Mike Magruder, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 Q:
2. Does the proposed Regional Reliability Standard pose an adverse impact to reliability or commerce
in a neighboring region or interconnection?

Hot Answers

 A: No (.a-b-78565)
Israel Perez, On Behalf of: Salt River Project - WECC - Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78560)
ACES Collaborators, Segment(s) 1, 9/29/2023
 -0 -0
© 2023 - NERC Ver 4.2.1.0 Machine Name: ERODVSBSWB01

Other Answers

 A: No (.a-b-78352)
BC Hydro, Segment(s) 3, 5, 1, 12/18/2018
 -0 -0

 A: No (.a-b-78357)
Andrea Jessup, On Behalf of: Bonneville Power Administration, WECC, Segments 1, 5, 6
 -0 -0

 A: No (.a-b-78371)
Robert Follini, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78381)

NA
Glen Farmer, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78446)
Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5
 -0 -0

 A: No (.a-b-78527)

None
Daniela Atanasovski, On Behalf of: APS - Arizona Public Service Co., , Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78550)
Mike Magruder, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 Q:
3. Does the proposed Regional Reliability Standard pose a serious and substantial threat to public
health, safety, welfare, or national security?
© 2023 - NERC Ver 4.2.1.0 Machine Name: ERODVSBSWB01

Hot Answers

 A: No (.a-b-78566)
Israel Perez, On Behalf of: Salt River Project - WECC - Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78561)
ACES Collaborators, Segment(s) 1, 9/29/2023
 -0 -0

Other Answers

 A: No (.a-b-78353)
BC Hydro, Segment(s) 3, 5, 1, 12/18/2018
 -0 -0

 A: No (.a-b-78358)
Andrea Jessup, On Behalf of: Bonneville Power Administration, WECC, Segments 1, 5, 6
 -0 -0

 A: No (.a-b-78372)
Robert Follini, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78382)
Glen Farmer, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78447)
Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5
 -0 -0

 A: No (.a-b-78528)

None
Daniela Atanasovski, On Behalf of: APS - Arizona Public Service Co., , Segments 1, 3, 5, 6
 -0 -0
© 2023 - NERC Ver 4.2.1.0 Machine Name: ERODVSBSWB01

 A: No (.a-b-78551)
Mike Magruder, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 Q:
4. Does the proposed Regional Reliability Standard pose a serious and substantial burden on
competitive markets within the interconnection that is not necessary for reliability?

Hot Answers

 A: No (.a-b-78567)
Israel Perez, On Behalf of: Salt River Project - WECC - Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78562)
ACES Collaborators, Segment(s) 1, 9/29/2023
 -0 -0

Other Answers

 A: No (.a-b-78354)
BC Hydro, Segment(s) 3, 5, 1, 12/18/2018
 -0 -0

 A: No (.a-b-78359)
Andrea Jessup, On Behalf of: Bonneville Power Administration, WECC, Segments 1, 5, 6
 -0 -0

 A: No (.a-b-78373)
Robert Follini, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78383)
Glen Farmer, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78448)
© 2023 - NERC Ver 4.2.1.0 Machine Name: ERODVSBSWB01

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5
 -0 -0

 A: No (.a-b-78529)

None
Daniela Atanasovski, On Behalf of: APS - Arizona Public Service Co., , Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78552)
Mike Magruder, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 Q:
5. Does the proposed Regional Reliability Standard meet at least one of the following criteria?
The proposed Regional Reliability Standard has more specific criteria for the same requirements
covered in a continent-wide standard.
The proposed Regional Reliability Standard has requirements that are not included in the
corresponding continent-wide standard.
The proposed regional difference is necessitated by a physical difference in the Bulk Power System.

Hot Answers

 A: Yes (.a-b-78568)

While there are regional and physical differences, the changes proposed are mainly grammatical and all are minor.
Israel Perez, On Behalf of: Salt River Project - WECC - Segments 1, 3, 5, 6
 -0 -0

 A: Yes (.a-b-78563)

Thank you for the opportunity to comment.
ACES Collaborators, Segment(s) 1, 9/29/2023
 -0 -0

Other Answers

 A: Yes (.a-b-78355)
BC Hydro, Segment(s) 3, 5, 1, 12/18/2018
 -0 -0

© 2023 - NERC
Machine Name: ERODVSBSWB01
 A:Ver
Yes4.2.1.0
(.a-b-78360)

Andrea Jessup, On Behalf of: Bonneville Power Administration, WECC, Segments 1, 5, 6
 -0 -0

 A: No (.a-b-78374)
Robert Follini, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: No (.a-b-78384)
Glen Farmer, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

 A: Yes (.a-b-78449)
Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5
 -0 -0

 A: Yes (.a-b-78530)

None
Daniela Atanasovski, On Behalf of: APS - Arizona Public Service Co., , Segments 1, 3, 5, 6
 -0 -0

 A: No (.a-b-78553)
Mike Magruder, On Behalf of: Avista - Avista Corporation, , Segments 1, 3, 5
 -0 -0

© 2023 - NERC Ver 4.2.1.0 Machine Name: ERODVSBSWB01

Comment Report
Project Name:

Regional Reliability Standard (WECC) | VAR-501-WECC-4 – Power System Stabilizer

Comment Period Start Date:

8/16/2023

Comment Period End Date:

9/29/2023

Associated Ballots:

There were 9 sets of responses, including comments from approximately 14 different people from approximately 9 companies
representing 4 of the Industry Segments as shown in the table on the following pages.

Questions
1. Do you agree the proposed Regional Reliability Standard was developed in a fair and open process, using the associated Regional
Reliability Standards Development Procedure?
2. Does the proposed Regional Reliability Standard pose an adverse impact to reliability or commerce in a neighboring region or
interconnection?
3. Does the proposed Regional Reliability Standard pose a serious and substantial threat to public health, safety, welfare, or national
security?
4. Does the proposed Regional Reliability Standard pose a serious and substantial burden on competitive markets within the interconnection
that is not necessary for reliability?
5. Does the proposed Regional Reliability Standard meet at least one of the following criteria?
•
•
•

The proposed Regional Reliability Standard has more specific criteria for the same requirements covered in a continent-wide
standard.
The proposed Regional Reliability Standard has requirements that are not included in the corresponding continent-wide standard.
The proposed regional difference is necessitated by a physical difference in the Bulk Power System.

Organization
Name

Name

BC Hydro and Adrian
Power
Andreoiu
Authority

ACES Power
Marketing

Segment(s)

1,3,5

Jodirah Green 1

Region

WECC

Group Name Group Member
Name
BC Hydro

Group
Member
Organization

Group
Member
Segment(s)

Group Member
Region

Hootan Jarollahi BC Hydro and 3
Power
Authority

WECC

Helen Hamilton
Harding

BC Hydro and 5
Power
Authority

WECC

Adrian Andreoiu BC Hydro and 1
Power
Authority

WECC

MRO,RF,SERC,Texas ACES
Bob Soloman
RE,WECC
Collaborators

Kris Carper

Hoosier
Energy
Electric
Cooperative

1

Arizona
1
Electric Power
Cooperative,
Inc.

RF

WECC

1. Do you agree the proposed Regional Reliability Standard was developed in a fair and open process, using the associated Regional
Reliability Standards Development Procedure?
Daniela Atanasovski - APS - Arizona Public Service Co. - 1,3,5,6
Answer

Yes

Document Name
Comment
None
Likes

0

Dislikes

0

Response
Adrian Andreoiu - BC Hydro and Power Authority - 1,3,5, Group Name BC Hydro
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Andrea Jessup - Bonneville Power Administration - 1,5,6 - WECC
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Robert Follini - Avista - Avista Corporation - 1,3,5

Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Glen Farmer - Avista - Avista Corporation - 1,3,5
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Richard Jackson - U.S. Bureau of Reclamation - 1,5
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Mike Magruder - Avista - Avista Corporation - 1,3,5
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Jodirah Green - ACES Power Marketing - 1 - WECC, Group Name ACES Collaborators
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Israel Perez - Salt River Project - 1,3,5,6 - WECC
Answer

Yes

Document Name
Comment
Likes

0

Dislikes
Response

0

2. Does the proposed Regional Reliability Standard pose an adverse impact to reliability or commerce in a neighboring region or
interconnection?
Daniela Atanasovski - APS - Arizona Public Service Co. - 1,3,5,6
Answer

No

Document Name
Comment
None
Likes

0

Dislikes

0

Response
Glen Farmer - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
NA
Likes

0

Dislikes

0

Response
Israel Perez - Salt River Project - 1,3,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Jodirah Green - ACES Power Marketing - 1 - WECC, Group Name ACES Collaborators

Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Mike Magruder - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Richard Jackson - U.S. Bureau of Reclamation - 1,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Robert Follini - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Andrea Jessup - Bonneville Power Administration - 1,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Adrian Andreoiu - BC Hydro and Power Authority - 1,3,5, Group Name BC Hydro
Answer

No

Document Name
Comment
Likes

0

Dislikes
Response

0

3. Does the proposed Regional Reliability Standard pose a serious and substantial threat to public health, safety, welfare, or national
security?
Daniela Atanasovski - APS - Arizona Public Service Co. - 1,3,5,6
Answer

No

Document Name
Comment
None
Likes

0

Dislikes

0

Response
Adrian Andreoiu - BC Hydro and Power Authority - 1,3,5, Group Name BC Hydro
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Andrea Jessup - Bonneville Power Administration - 1,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Robert Follini - Avista - Avista Corporation - 1,3,5

Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Glen Farmer - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Richard Jackson - U.S. Bureau of Reclamation - 1,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Mike Magruder - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Jodirah Green - ACES Power Marketing - 1 - WECC, Group Name ACES Collaborators
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Israel Perez - Salt River Project - 1,3,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes
Response

0

4. Does the proposed Regional Reliability Standard pose a serious and substantial burden on competitive markets within the interconnection
that is not necessary for reliability?
Daniela Atanasovski - APS - Arizona Public Service Co. - 1,3,5,6
Answer

No

Document Name
Comment
None
Likes

0

Dislikes

0

Response
Israel Perez - Salt River Project - 1,3,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Jodirah Green - ACES Power Marketing - 1 - WECC, Group Name ACES Collaborators
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Mike Magruder - Avista - Avista Corporation - 1,3,5

Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Richard Jackson - U.S. Bureau of Reclamation - 1,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Glen Farmer - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Robert Follini - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Andrea Jessup - Bonneville Power Administration - 1,5,6 - WECC
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Adrian Andreoiu - BC Hydro and Power Authority - 1,3,5, Group Name BC Hydro
Answer

No

Document Name
Comment
Likes

0

Dislikes
Response

0

5. Does the proposed Regional Reliability Standard meet at least one of the following criteria?
•
•
•

The proposed Regional Reliability Standard has more specific criteria for the same requirements covered in a continent-wide
standard.
The proposed Regional Reliability Standard has requirements that are not included in the corresponding continent-wide standard.
The proposed regional difference is necessitated by a physical difference in the Bulk Power System.

Robert Follini - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Glen Farmer - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes

0

Response
Mike Magruder - Avista - Avista Corporation - 1,3,5
Answer

No

Document Name
Comment
Likes

0

Dislikes
Response

0

Daniela Atanasovski - APS - Arizona Public Service Co. - 1,3,5,6
Answer

Yes

Document Name
Comment
None
Likes

0

Dislikes

0

Response
Jodirah Green - ACES Power Marketing - 1 - WECC, Group Name ACES Collaborators
Answer

Yes

Document Name
Comment
Thank you for the opportunity to comment.
Likes

0

Dislikes

0

Response
Israel Perez - Salt River Project - 1,3,5,6 - WECC
Answer

Yes

Document Name
Comment
While there are regional and physical differences, the changes proposed are mainly grammatical and all are minor.
Likes

0

Dislikes

0

Response
Adrian Andreoiu - BC Hydro and Power Authority - 1,3,5, Group Name BC Hydro
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Andrea Jessup - Bonneville Power Administration - 1,5,6 - WECC
Answer

Yes

Document Name
Comment
Likes

0

Dislikes

0

Response
Richard Jackson - U.S. Bureau of Reclamation - 1,5
Answer

Yes

Document Name
Comment
Likes

0

Dislikes
Response

0

<Public>

Response to Comments
Posting 1—45-Day at NERC
August 16 through September 29, 2023
WECC-0148 VAR-501-WECC-4
Power System Stabilizer
Information Only Filing

Posting 1—45-Day NERC
The WECC-0148 VAR-501-WECC-4, Power System Stabilizer Drafting Team (DT) thanks everyone who
submitted comments on the proposed project. WECC-0148 is an information-only filing proposing no
Substantive changes. 1

Posting
This project was posted for comment by NERC from August 16, 2023, through September 29, 2023.
NERC distributed notice for the posting on August 16, 2023.
NERC asked stakeholders to provide feedback on the proposed project through a standardized
electronic template.
NERC reported there “were 9 sets of responses, including comments from approximately 14 different
people from approximately 9 companies representing 4 of the Industry Segments.”
After review of the NERC-provided document, WECC found responses from seven organizations
(some with member organization subcomponents), and 13 persons identified in the following Table of
Respondents.

Location of Comments
All comments provided to WECC by NERC can be reviewed in their original format on the WECC-0148
project page under the “Submit and Review Comments” accordion.

Changes in Response to Comment
After consideration of all comments received, no further changes were made to this project.

The terms Substantive and Non-Substantive are defined terms found in the WECC Relibaility Standards
Development Procedures.
https://www.wecc.org/Reliability/WECC%20Reliability%20Standards%20Development%20Procedures%20%20FERC%20Approved%2009-13-2021.pdf
1

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www.wecc.org

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Minority View
No minority views were raised.

Proposed Effective Date
The proposed Standard can be implemented immediately upon receipt of final regulatory approval.

Information Only—No Substantive Changes
This project represents an “Information Only” filing with no Substantive changes.
Per the WECC Relibaility Standards Development Procedures (Procedures), if no Substantive changes
are requested to a Regional Standard, no further due process is required. Specifically, WECC Board of
Directors (Board) approval is not required.
On July 11, 2022, a list 2 of proposed Non-Substantive changes was distributed to the Standards Email
List (SEL) inviting comments or concerns to be forwarded to WECC Standards staff. A redline and a
clean version of the project was posted on the WECC-0148, Posting 1 for Comment accordion. No
comments were received.
On July 16, 2022, WECC posted a letter 3 to the WSC informing the WSC of its scope and authority to
address an information only filing. The letter was published to the WECC-0148 home page on the
Posting 1 for Comment accordion.
On December 6, 2022, during a duly noticed WSC meeting, the WSC reviewed the letter from July 16,
2022, and was briefed on the WSC’s Procedural authority to approve the project with no further due
process, so long as all changes were deemed Non-Substantive.
The WSC concurred 4 that all proposed changes were Non-Substantive. Because the proposed changes
are all Non-Substantive, the WSC also concurred that neither a posting for comment, ballot, Board
approval, nor an Implementation Plan were required per the Procedures.

Table of Respondents
Organization

1

ACES Power Marketing (ACES)

Bob Soloman, Jodirah Green, Kris Carper

2

Arizona Public Service Company (APS)

Daniel Atanasovski

3

Avista Corporation

Glen Farmer, Mike Magruder, Robert Follini

https://www.wecc.org/Administrative/WECC-0148%20Notice%20of%20No%20Substantive%20Change.pdf
https://www.wecc.org/Reliability/WECC-0148%20VAR-501-WECC-3.1%20%20Letter%20to%20WSC%20Requesting%20Information%20Only%20Filing%20-%20FINAL.docx
4 https://www.wecc.org/Administrative/2022-0316%20WSC%20Proposed%20Meeting%20Minutes%20for%20approval%202022-12-06-2022%20%20FINAL%20FROM%20TECH.docx
2
3

2

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Organization

4

BC Hydro and Power Authority (BC)

Adrian Andreoiu, Helen Hamilton Harding,
Hootan Jarollahi

5

Bonneville Power Administration (BPA)

Andrea Jessup

6

Salt River Project (SRP)

Israel Perez

7

United States Bureau of Reclamation

Richard Jackson

(USB)

Contacts and Appeals
If you feel your comment has been omitted or overlooked, please contact W. Shannon Black, WECC
Consultant, at (503) 307-5782. In addition, there is a WECC Reliability Standards appeals process.

3

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Index to NERC-provided Questions, Comments, and Responses
Question
1) Do you agree the proposed Regional Reliability Standard was developed in a fair and open
process, using the associated Regional Reliability Standards Development Procedure?
2) Does the proposed Regional Reliability Standard pose an adverse impact to reliability or
commerce in a neighboring region or interconnection?
3) Does the proposed Regional Reliability Standard pose a serious and substantial threat to public
health, safety, welfare, or national security?
4) Does the proposed Regional Reliability Standard pose a serious and substantial burden on
competitive markets within the interconnection that is not necessary for reliability?
5) Does the proposed Regional Reliability Standard meet at least one of the following criteria
a. The proposed Regional Reliability Standard has more specific criteria for the same
requirements covered in a continent-wide standard.
b. The proposed Regional Reliability Standard has requirements that are not included in
the corresponding continent-wide standard.
c. The proposed regional difference is necessitated by a physical difference in the Bulk
Power System.

4

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1

Comment Summary. For proposed changes and avenues forward, please see the preamble.
1) Question 1—Do you agree the proposed Regional Reliability Standard was developed in a fair and
open process, using the associated Regional Reliability Standards Development Procedure?
Commenter

Comment or Response

ACES

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

Yes

Response

5

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

6

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 2— Does the proposed Regional Reliability Standard pose an adverse impact to
reliability or commerce in a neighboring region or interconnection?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

7

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

8

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 3— Does the proposed Regional Reliability Standard pose a serious and substantial
threat to public health, safety, welfare, or national security?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

9

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

10

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.

1) Question 4— Does the proposed Regional Reliability Standard pose a serious and substantial
burden on competitive markets within the interconnection that is not necessary for reliability?
Commenter

Comment or Response

ACES

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

No.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

11

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BC

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

No

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

12

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
Comment Summary. For proposed changes and avenues forward, please see the preamble.
1) Question 5—Does the proposed Regional Reliability Standard meet at least one of the following
criteria:
d. The proposed Regional Reliability Standard has more specific criteria for the same
requirements covered in a continent-wide standard.
e.

The proposed Regional Reliability Standard has requirements that are not included in the
corresponding continent-wide standard.

f.

The proposed regional difference is necessitated by a physical difference in the Bulk Power
System.

Commenter

Comment or Response

ACES

Yes. Thank you for the opportunity to comment.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

APS

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

Avista – Glen Farmer

No

Response
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

Avista - Mike Magruder

No

Response
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

Avista - Robert Follini

No

Response

13

<Public>

WECC-0148 NERC 45-Day Posting
Response to Comments, Posting 1
The WECC-0148 Drafting Team (DT) appreciates Avista’s negative response; however, Avista has failed to
explain their response, identify any issues, or suggest any proposed changes. As such, the DT can neither
identify nor remedy Avista’s concern.
Commenter

Comment or Response

BC

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

BPA

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

SRP

Yes. While there are regional and physical differences, the
changes proposed are mainly grammatical and all are minor.

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.
Commenter

Comment or Response

USB

Yes

Response
The WECC-0148 Drafting Team (DT) appreciates each respondent’s engagement in the Standards development
process.

14

Exhibit C
Standard Dra�ing Team Roster for Project
WECC-0148 Power System Stabilizer

<Public>

Attachment L
Drafting Team Roster
WECC-0148 VAR-501-WECC-4
Five-year Review

Drafting Team Roster
Below please find a brief biography for each member of the WECC-0148 VAR-501-WECC-4, Power
System Stabilizer, Five-year Review Drafting Team.
Name

Qualifications

Greg Anderson,

Mr. Anderson is the subject matter expert for generation and excitation

Southern

systems for the Southern California Edison Company. He has over 33

California Edison

years of experience in the utility industry, with responsibilities for
coordinating WECC testing of generation assets. He has been a WECC
participant since 1997 and a member of the Control Work Group since
2003.

Joel Anthes,
Pacific Gas and
Electric

Mr. Anthes is a Senior Electrical Engineer with Pacific Gas and Electric
Company’s Power Generation organization. Mr. Anthes has more than 16
years of experience in the electrical and power generation industries. Over
the past nine years, he has led the development of multiple technical
programs related to electrical generation and excitation system protection,
control system tuning and modeling, and generator electrical ratings. Mr.
Anthes is a registered professional engineer in the state of California and
plays an active role in the development of industry best practices and
regulatory standards for NERC. Recent experience includes:
•

Member of the drafting team for NERC Project 2020-02
Transmission-connected Dynamic Reactive Resources.

•

Power system stabilizer (PSS) tuning and validation.

•

Development of tools for numerical calculation of generator field
current. Performs generator heat runs to prove safe increase of
electrical rating beyond existing nameplate.

•

Development of program for dynamic modeling of generators,
voltage regulators, governors, and power system stabilizers.
Development of associated programs for NERC regulatory
compliance.

155 North 400 West | Suite 200 | Salt Lake City, Utah 84103
www .wecc.or g

<Public>

Attachment L
•

Developed custom tools for determining generator electrical
characteristics, impedances, time constants, phase response, and
capability curves for synchronous generators. Oversees training of
other engineers in the proper implementation of these tools.

•

Commissions and tests excitation systems, voltage regulators, and
power system stabilizers.

•

Performs Root Cause Analyses using industry standard
methodologies for operational safety incidents and major
equipment failures.

•

Developed recommendations for corrective actions to effectively
prevent the recurrence of equipment failure and human
performance errors.

Shane Kronebusch,
L&S Electric, Inc.

Mr. Kronebusch is the Lead Electrical Engineer and subject matter expert
for generation and excitation systems for L&S Electric, Inc. He has over 31
years of experience in the utility industry, including:
•

Developing the LS-AES excitation system.

•

Designing, installing, and commissioning exciters and governors
across a wide range of units.

•

Performing of testing and model validation reports for NERC
MOD-025, -026, & -027.

•

Coordinating and preforming WECC testing of generation assets as
an employee of BC Hydro Generation Engineering and
Maintenance Services before joining L&S Electric, Inc. in 2010.

•

Participating as a member of the WECC Control Work Group since
2006 and drafting team member of WECC-0099/0107.

Matthew

Mr. McDonald is a Senior Electrical Engineer in the Technical Projects

McDonald, Arizona Engineering department with 15 years of experience in the utility industry.
Public Service

He holds a Bachelor of Science from Pennsylvania State University as well
as a professional engineering license. His expertise and experience include
the following:
•

13 years’ hands-on experience installing, troubleshooting,
commissioning, and tuning excitation systems and generator
protection relays.

•

Five years of experience performing generator, excitation, and PSS
model validation via simulation and live testing.

2

<Public>

Attachment L
•

Excitation system subject matter expert for Arizona Public Service
for the past four years.

•

NERC/WECC compliance lead for VAR-501-3, PRC-19-2, PRC-002,
PRC-27-1 and PRC-25-2.

•

Other responsibilities and roles have included generator excitation
instructor, improvisational field testing, synchro-phasor and digital
fault recorder commissioning.

Kimberly Turco,

Ms. Turco has worked for Constellation Energy Generation (CEG) for 10

Constellation

years, with the last two years in NERC compliance and supporting ISO

Energy

compliance. CEG is actively involved in NERC’s Standards Under
Development process and would like to take this opportunity for direct
involvement in the review of VAR-501-WECC. Kim comes with a wide
background in energy and compliance that would be an asset in the
standards review process.
Kim’s background:
•

Worked as a subject matter expert in AESO in day-ahead bidding
and electronic transaction systems (ETS).

•

Drafted CEG’s Grande Prairie Generation generating station’s
Transmission Must Run Contract.

•

A barred attorney.

•

NERC compliance SME and compliance contact for CEG’s WECC
and Alberta generating facilities.

•

Lead on historical submittal of Automatic Voltage Regulator and
Power System Stabilizer Outage reporting.

Kim has the full support of CEG’s NERC Compliance Group and will be
able to dedicate the time and resources demanded of a member of the
Standards Drafting Team.

3