Reliability Standard VAR-001-5

VAR-001-5— Voltage and Reactive Control

A. Introduction
1.

Title:

2.

Number: VAR-001-5

3.

Purpose: To ensure that voltage levels, reactive flows, and reactive resources are
monitored, controlled, and maintained within limits in Real-time to protect
equipment and the reliable operation of the Interconnection.

4.

Applicability:

Voltage and Reactive Control

4.1. Transmission Operators
4.2. Generator Operators within the Western Interconnection (for the WECC
Variance)
5.

Effective Date:
5.1. The standard shall become effective on the first day of the first calendar
quarter after the date that the standard is approved by an applicable
governmental authority or as otherwise provided for in a jurisdiction where
approval by an applicable governmental authority is required for a standard to
go into effect. Where approval by an applicable governmental authority is not
required, the standard shall become effective on the first day of the first
calendar quarter after the date the standard is adopted by the NERC Board of
Trustees or as otherwise provided for in that jurisdiction.

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VAR-001-5— Voltage and Reactive Control

B. Requirements and Measures
R1. Each Transmission Operator shall specify a system voltage schedule (which is either
a range or a target value with an associated tolerance band) as part of its plan to
operate within System Operating Limits and Interconnection Reliability Operating
Limits. [Violation Risk Factor: High] [Time Horizon: Operations Planning]
1.1. Each Transmission Operator shall provide a copy of the voltage schedules
(which is either a range or a target value with an associated tolerance band) to
its Reliability Coordinator and adjacent Transmission Operators within 30
calendar days of a request.
M1. The Transmission Operator shall have evidence that it specified system voltage
schedules using either a range or a target value with an associated tolerance band.
For part 1.1, the Transmission Operator shall have evidence that the voltage
schedules (which is either a range or a target value with an associated tolerance
band) were provided to its Reliability Coordinator and adjacent Transmission
Operators within 30 calendar days of a request. Evidence may include, but is not
limited to, emails, website postings, and meeting minutes.
R2. Each Transmission Operator shall schedule sufficient reactive resources to regulate
voltage levels under normal and Contingency conditions. Transmission Operators
can provide sufficient reactive resources through various means including, but not
limited to, reactive generation scheduling, transmission line and reactive resource
switching, and using controllable load. [Violation Risk Factor: High] [Time Horizon:
Real-time Operations, Same-day Operations, and Operations Planning]
M2. Each Transmission Operator shall have evidence of scheduling sufficient reactive
resources based on their assessments of the system. For the operations planning
time horizon, Transmission Operators shall have evidence of assessments used as
the basis for how resources were scheduled.
R3. Each Transmission Operator shall operate or direct the Real-time operation of
devices to regulate transmission voltage and reactive flow as necessary. [Violation
Risk Factor: High] [Time Horizon: Real-time Operations, Same-day Operations, and
Operations Planning]
M3. Each Transmission Operator shall have evidence that actions were taken to operate
capacitive and inductive resources as necessary in Real-time. This may include, but is
not limited to, instructions to Generator Operators to: 1) provide additional voltage
support; 2) bring resources on-line; or 3) make manual adjustments.
R4. Each Transmission Operator shall specify the criteria that will exempt generators: 1)
from following a voltage or Reactive Power schedule, 2) from having its automatic
voltage regulator (AVR) in service or from being in voltage control mode, or 3) from
having to make any associated notifications. [Violation Risk Factor: Lower] [Time
Horizon: Operations Planning]

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VAR-001-5— Voltage and Reactive Control

4.1 If a Transmission Operator determines that a generator has satisfied the
exemption criteria, it shall notify the associated Generator Operator.
M4. Each Transmission Operator shall have evidence of the documented criteria for
generator exemptions.
For part 4.1, the Transmission Operator shall also have evidence to show that, for
each generator in its area that is exempt: 1) from following a voltage or Reactive
Power schedule, 2) from having its automatic voltage regulator (AVR) in service or
from being in voltage control mode, or 3) from having to make any notifications, the
associated Generator Operator was notified of this exemption.
R5. Each Transmission Operator shall specify a voltage or Reactive Power schedule
(which is either a range or a target value with an associated tolerance band) at
either the high voltage side or low voltage side of the generator step-up transformer
at the Transmission Operator’s discretion. [Violation Risk Factor: Medium] [Time
Horizon: Operations Planning]
5.1. The Transmission Operator shall provide the voltage or Reactive Power
schedule (which is either a range or a target value with an associated tolerance
band) to the associated Generator Operator and direct the Generator Operator
to comply with the schedule in automatic voltage control mode (the AVR is in
service and controlling voltage).
5.2. The Transmission Operator shall provide the Generator Operator with the
notification requirements for deviations from the voltage or Reactive Power
schedule (which is either a range or a target value with an associated tolerance
band).
5.3. The Transmission Operator shall provide the criteria used to develop voltage
schedules or Reactive Power schedule (which is either a range or a target value
with an associated tolerance band) to the Generator Operator within 30 days
of receiving a request.
M5. The Transmission Operator shall have evidence of a documented voltage or Reactive
Power schedule (which is either a range or a target value with an associated
tolerance band).
For part 5.1, the Transmission Operator shall have evidence it provided a voltage or
Reactive Power schedule (which is either a range or a target value with an
associated tolerance band) to the applicable Generator Operators, and that the
Generator Operator was directed to comply with the schedule in automatic voltage
control mode, unless exempted.
For part 5.2, the Transmission Operator shall have evidence it provided notification
requirements for deviations from the voltage or Reactive Power schedule (which is
either a range or a target value with an associated tolerance band). For part 5.3, the
Transmission Operator shall have evidence it provided the criteria used to develop
voltage schedules or Reactive Power schedule (which is either a range or a target
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VAR-001-5— Voltage and Reactive Control

value with an associated tolerance band) within 30 days of receiving a request by a
Generator Operator.
R6. After consultation with the Generator Owner regarding necessary step-up
transformer tap changes and the implementation schedule, the Transmission
Operator shall provide documentation to the Generator Owner specifying the
required tap changes, a timeframe for making the changes, and technical
justification for these changes. [Violation Risk Factor: Lower] [Time Horizon:
Operations Planning]
M6. The Transmission Operator shall have evidence that it provided documentation to
the Generator Owner when a change was needed to a generating unit’s step-up
transformer tap in accordance with the requirement and that it consulted with the
Generator Owner.

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VAR-001-5— Voltage and Reactive Control

C. Compliance
1.

Compliance Monitoring Process:

1.1. Compliance Enforcement Authority:
As defined in the NERC Rules of Procedure, “Compliance Enforcement Authority”
refers to NERC or the Regional Entity in their respective roles of monitoring and
enforcing compliance with the NERC Reliability Standards.
1.2. Evidence Retention:
The following evidence retention periods identify the period of time a registered
entity is required to retain specific evidence to demonstrate compliance. For
instances in which the evidence retention period specified below is shorter than the
time since the last audit, the Compliance Enforcement Authority may ask the
registered entity to provide other evidence to show that it was compliant for the full
time period since the last audit.
The Transmission Operator shall retain evidence for Measures M1 through M6 for
12 months. The Compliance Monitor shall retain any audit data for three years.
1.3. Compliance Monitoring and Assessment Processes:
“Compliance Monitoring and Assessment Processes” 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.
1.4. Additional Compliance Information:
None

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VAR-001-5— Voltage and Reactive Control

Table of Compliance Elements
R#

Time
Horizon

R1

Operations
Planning

R2

Real-time
Operations,
Same-day
Operations,
and
Operations
Planning

R3

Real-time
Operations,
Same-day
Operations,
and
Operations
Planning

VRF

High

High

High

Violation Severity Levels

Lower VSL

N/A

N/A

N/A

Moderate VSL

High VSL

Severe VSL

N/A

N/A

The Transmission
Operator does not
specify a system
voltage schedule
(which is either a
range or a target
value with an
associated tolerance
band).

N/A

The Transmission
Operator does not
schedule sufficient
reactive resources as
necessary to avoid
violating an SOL.

The Transmission
Operator does not
schedule sufficient
reactive resources as
necessary to avoid
violating an IROL.

N/A

The Transmission
Operator does not
operate or direct any
real-time operation
of devices as
necessary to avoid
violating an SOL.

The Transmission
Operator does not
operate or direct any
real-time operation of
devices as necessary
to avoid violating an
IROL.

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VAR-001-5— Voltage and Reactive Control

R#

R4

R5

Time
Horizon

Operations
Planning

Operations
Planning

VRF

Lower

Medium

Violation Severity Levels

Lower VSL

N/A

N/A

Moderate VSL

High VSL

N/A

The Transmission
Operator has
exemption criteria
and notified the
Generator Operator,
but the Transmission
Operator does not
have evidence of the
notification to the
Generator Operator.

The Transmission
Operator does not
provide the criteria
for voltage or
Reactive Power
schedules (which is
either a range or a
target value with an
associated tolerance
band) after 30 days
of a request.

The Transmission
Operator does not
provide voltage or
Reactive Power
schedules (which is
either a range or a
target value with an
associated tolerance
band) to all
Generator
Operators.

Severe VSL

The Transmission
Operator does not
have exemption
criteria.

The Transmission
Operator does not
provide voltage or
Reactive Power
schedules (which is
either a range or a
target value with an
associated tolerance
band) to any
Generator Operators.
Or
The Transmission
Operator does not
provide the
Generator Operator
with the notification
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VAR-001-5— Voltage and Reactive Control

R#

R6

Time
Horizon

Operations
Planning

VRF

Lower

Violation Severity Levels

Lower VSL

The Transmission
Operator does not
provide either the
technical justification
or timeframe for
changing generator
step-up tap settings.

Moderate VSL

N/A

High VSL

N/A

Severe VSL
requirements for
deviations from the
voltage or Reactive
Power schedule
(which is either a
range or a target
value with an
associated tolerance
band).
The Transmission
Operator does not
provide the technical
justification and the
timeframe for
changing generator
step-up tap settings.

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VAR-001-5 Application Guidelines

D. Regional Variances
The following Interconnection-wide variance shall be applicable in the Western Electricity
Coordinating Council (WECC) and replaces, in their entirety, Requirements R4 and R5.
Please note that Requirement R4 is deleted and R5 is replaced with the following
requirements.
Requirements and Measures
E.A.13

Each Transmission Operator shall issue any one of the following types of
voltage schedules to the Generator Operators for each of their generation
resources that are on-line and part of the Bulk Electric System within the
Transmission Operator Area: [Violation Risk Factor: Medium] [Time Horizon:
Operations Planning and Same-day Operations]
•

A voltage set point with a voltage tolerance band and a specified period.

•

An initial volt-ampere reactive output or initial power factor output with
a voltage tolerance band for a specified period that the Generator
Operator uses to establish a generator bus voltage set point.

•

A voltage band for a specified period.

M.E.A.13 Each Transmission Operator will have evidence that it provided the voltage
schedules to the Generator Operator, as required in E.A.13. Evidence may
include, but is not limited to, dated spreadsheets, reports, voice recordings, or
other documentation containing the voltage schedule including set points,
tolerance bands, and specified periods as required in Requirement E.A.13.
E.A.14

Each Transmission Operator shall provide one of the following voltage
schedule reference points for each generation resource in its area to the
Generator Operator. [Violation Risk Factor: Medium] [Time Horizon:
Operations Planning and Same-day Operations]
•

The generator terminals.

•

The high side of the generator step-up transformer.

•

The point of interconnection.

•

A location designated by mutual agreement between the Transmission
Operator and Generator Operator.

M.E.A.14 The Transmission Operator will have evidence that it provided one of the
voltage schedule reference points for each generation resource in its area to
the Generator Operator, as required in E.A.14. Evidence may include, but is
not limited to dated letters, e-mail, or other documentation that contains
notification to the Generator Operator of the voltage schedule reference point
for each generation resource.
E.A.15

Each Generator Operator shall provide its voltage set point conversion
methodology from the point in Requirement E.A.14 to the generator terminals
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VAR-001-5 Application Guidelines
within 30 calendar days of request by its Transmission Operator. [Violation Risk
Factor: Lower] [Time Horizon: Operations Planning]
M.E.A.15 The Generator Operator will have evidence that within 30 calendar days of
request by its Transmission Operator it provided its voltage set point
conversion methodology from the point in Requirement E.A.14 to the
generator terminals, as required in E.A.15. Evidence may include, but is not
limited to, dated reports, spreadsheets, or other documentation.
E.A.16

Each Transmission Operator shall provide to the Generator Operator, within 30
calendar days of a request for data by the Generator Operator, its transmission
equipment data and operating data that supports development of the voltage
set point conversion methodology. [Violation Risk Factor: Lower] [Time
Horizon: Operations Planning]

M.E.A.16 The Transmission Operator will have evidence that within 30 calendar days of
request by its Generator Operator it provided data to support development of
the voltage set point conversion methodology, as required in E.A.16. Evidence
may include, but is not limited to, dated reports, spreadsheets, or other
documentation.
E.A.17

Each Generator Operator shall meet the following control loop specifications if
the Generator Operator uses control loops external to the automatic voltage
regulators (AVR) to manage Mvar loading: [Violation Risk Factor: Medium]
[Time Horizon: Real-time Operations]
E.A.17.1 Each control loop’s design incorporates the AVR’s automatic voltage
controlled response to voltage deviations during System
Disturbances.
E.A.17.2. Each control loop is only used by mutual agreement between the
Generator Operator and the Transmission Operator affected by the
control loop.

M.E.A.17 If the Generator Operator uses outside control loops to manage Mvar loading,
the Generator Operator will have evidence that it met the control loop
specifications in sub-parts E.A.17.1 through E.A.17.2, as required in E.A.17 and
its sub-parts. Evidence may include, but is not limited to, design specifications
with identified agreed-upon control loops, system reports, or other dated
documentation.

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VAR-001-5 Application Guidelines

Violation Severity Levels
E#

Lower VSL

Moderate VSL

High VSL

Severe VSL

E.A.13

For the specified
period, the
Transmission
Operator did not
issue one of the
voltage schedules
listed in E.A.13 to at
least one
generation
resource but less
than or equal to 5%
of the generation
resources that are
on-line and part of
the BES in the
Transmission
Operator Area.

For the specified
period, the
Transmission
Operator did not
issue one of the
voltage schedules
listed in E.A.13 to
more than 5% but
less than or equal
to 10% of the
generation
resources that are
on-line and part of
the BES in the
Transmission
Operator Area.

For the specified
period, the
Transmission
Operator did not
issue one of the
voltage schedules
listed in E.A.13 to
more than 10% but
less than or equal
to 15% of the
generation
resources that are
on-line and part of
the BES in the
Transmission
Operator Area.

For the specified
period, the
Transmission
Operator did not
issue one of the
voltage schedules
listed in E.A.13 to
more than 15% of
the generation
resources that are
on-line and part of
the BES in the
Transmission
Operator Area.

E.A.14

The Transmission
Operator did not
provide a voltage
schedule reference
point for at least
one but less than or
equal to 5% of the
generation
resources in the
Transmission
Operator area.

The Transmission
Operator did not
provide a voltage
schedule reference
point for more than
5% but less than or
equal to 10% of the
generation
resources in the
Transmission
Operator Area.

The Transmission
Operator did not a
voltage schedule
reference point for
more than 10% but
less than or equal
to 15% of the
generation
resources in the
Transmission
Operator Area.

The Transmission
Operator did not
provide a voltage
schedule reference
point for more than
15% of the
generation
resources in the
Transmission
Operator Area.

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VAR-001-5 Application Guidelines
E#

Lower VSL

Moderate VSL

High VSL

Severe VSL

E.A.15

The Generator
Operator provided
its voltage set
point conversion
methodology
greater than 30
days but less than
or equal to 60
days of a request
by the
Transmission
Operator.

The Generator
Operator provided
its voltage set
point conversion
methodology
greater than 60
days but less than
or equal to 90
days of a request
by the
Transmission
Operator.

The Generator
Operator provided
its voltage set
point conversion
methodology
greater than 90
days but less than
or equal to 120
days of a request
by the
Transmission
Operator.

The Generator
Operator did not
provide its
voltage set point
conversion
methodology
within 120 days of
a request by the
Transmission
Operator.

E.A.16

The Transmission
Operator provided
its data to
support
development of
the voltage set
point conversion
methodology than
30 days but less
than or equal to
60 days of a
request by the
Generator
Operator.

The Transmission
Operator provided
its data to
support
development of
the voltage set
point conversion
methodology
greater than 60
days but less than
or equal to 90
days of a request
by the Generator.
Operator.

The Transmission
Operator provided
its data to
support
development of
the voltage set
point conversion
methodology
greater than 90
days but less than
or equal to 120
days of a request
by the Generator.
Operator.

The Transmission
Operator did not
provide its data to
support
development of
the voltage set
point conversion
methodology
within 120 days of
a request by the
Generator
Operator.

N/A

The Generator
Operator did not
meet the control
loop specifications
in E.A.17.2 when
the Generator
Operator uses
control loop
external to the AVR
to manage Mvar
loading.

The Generator
Operator did not
meet the control
loop specifications
in E.A.17.1 when
the Generator
Operator uses
control loop
external to the AVR
to manage Mvar
loading.

The Generator
Operator did not
meet the control
loop specifications
in E.A.17.1 through
E.A.17.2 when the
Generator Operator
uses control loop
external to the AVR
to manage Mvar
loading.

E.A.17

E.

Interpretations
None
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VAR-001-5 Application Guidelines
F.

Associated Documents
None.

Version History
Version

Date

Action

Change Tracking

0

April 1, 2005

Effective Date

New

1

August 2, 2006

BOT Adoption

Revised

1

June 18, 2007

FERC approved Version 1 of the standard.

Revised

1

July 3, 2007

Added “Generator Owners” and “Generator
Operators” to Applicability section.

Errata

1

August 23, 2007

Removed “Generator Owners” and “Generator
Operators” to Applicability section.

Errata

2

August 5, 2010

Adopted by NERC Board of Trustees; Modified to
address Order No. 693 Directives contained in
paragraphs 1858 and 1879.

Revised

2

January 10, 2011

FERC issued letter order
approving the addition of LSEs
and Controllable Load to the
standard.

Revised

3

May 9, 2012

Adopted by NERC Board of Trustees; Modified to
add a WECC region variance

Revised

3

June 20, 2013

FERC issued order approving VAR-001-3

Revised

3

November 21,
2013

R5 and associated elements approved by FERC for
retirement as part of the Paragraph 81 project
(Project 2013-02)

Revised

4

February 6, 2014 Adopted by NERC Board of Trustees

4

August 1, 2014

4.1

August 25, 2015

4.1

November 13,
2015
June 14, 2017
August 10, 2017
September 26,
2017
August 16, 2018

4.2
4.2
4.2
5

FERC issued letter order issued approving VAR001-4
Added “or” to Requirement R5, 5.3 to read:
schedules or Reactive Power
FERC Letter Order approved errata to VAR-001-4.1.
Docket RD15-6-000
Project 2016-EPR-02 errata recommendations
Adopted by NERC Board of Trustees
FERC Letter Order issued approving VAR-001-4.2
Docket No. RD17-7-000.
Adopted by NERC Board of Trustees

Revised

Errata
Errata
Errata
Errata
1) In E.A.14
“Area” was
changed to
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VAR-001-5 Application Guidelines

5

10/15/2018

FERC Order issued approving VAR-001-5 Docket
No. RD18-8-000.

“area.”; 2) E.A.15
and associated
elements were
eliminated; 3)
Measures were
updated and
relocated
matching current
conventions,
replacing “shall”
with “will”; 4)
typographical
errors in VSL
Table for E.A.17
were corrected;
5) format was
updated.

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VAR-001-5 Application Guidelines
Guidelines and Technical Basis
For technical basis for each requirement, please review the rationale provided for each
requirement.
Rationale:

During development of this standard, text boxes were embedded within the standard to explain
the rationale for various parts of the standard. Upon BOT approval, the text from the rationale
text boxes was moved to this section.
Rationale for R1:
Paragraph 1868 of Order No. 693 requires NERC to add more "detailed and definitive
requirements on “established limits” and “sufficient reactive resources”, and identify
acceptable margins (i.e. voltage and/or reactive power margins)." Since Order No. 693 was
issued, however, several FAC and TOP standards have become enforceable to add more
requirements around voltage limits. More specifically, FAC-011 and FAC-014 require that
System Operating Limits (SOLs) and reliability margins are established. The NERC Glossary
definition of SOLs includes both: 1) voltage stability ratings (Applicable pre- and postContingency Voltage Stability) and 2) System Voltage Limits (Applicable pre- and postContingency voltage limits). Therefore, for reliability reasons Requirement R1 now requires a
Transmission Operator (TOP) to set voltage or Reactive Power schedules with associated
tolerance bands. Further, since neighboring areas can affect each other greatly, each TOP must
also provide a copy of these schedules to its Reliability Coordinator (RC) and adjacent TOP upon
request.
Rationale for R2:
Paragraph 1875 from Order No. 693 directed NERC to include requirements to run voltage
stability analysis periodically, using online techniques where commercially available and offline
tools when online tools are not available. This standard does not explicitly require the periodic
voltage stability analysis because such analysis would be performed pursuant to the SOL
methodology developed under the FAC standards. TOP standards also require the TOP to
operate within SOLs and Interconnection Reliability Operating Limits (IROL). The VAR standard
drafting team (SDT) and industry participants also concluded that the best models and tools are
the ones that have been proven and the standard should not add a requirement for a
responsible entity to purchase new online simulations tools. Thus, the VAR SDT simplified the
requirements to ensuring sufficient reactive resources are online or scheduled. Controllable
load is specifically included to answer FERC's directive in Order No. 693 at Paragraph 1879.

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VAR-001-5 Application Guidelines
Rationale for R3:
Similar to Requirement R2, the VAR SDT determined that for reliability purposes, the TOP must
ensure sufficient voltage support is provided in Real-time in order to operate within an SOL.
Rationale for R4:
The VAR SDT received significant feedback on instances when a TOP would need the flexibility
for defining exemptions for generators. These exemptions can be tailored as the TOP deems
necessary for the specific area’s needs. The goal of this requirement is to provide a TOP the
ability to exempt a Generator Operator (GOP) from: 1) a voltage or Reactive Power schedule, 2)
a setting on the AVR, or 3) any VAR-002 notifications based on the TOP’s criteria. Feedback
from the industry detailed many system events that would require these types of exemptions
which included, but are not limited to: 1) maintenance during shoulder months, 2) scenarios
where two units are located within close proximity and both cannot be in voltage control mode,
and 3) large system voltage swings where it would harm reliability if all GOP were to notify their
respective TOP of deviations at one time. Also, in an effort to improve the requirement, the
sub-requirements containing an exemption list were removed from the currently enforceable
standard because this created more compliance issues with regard to how often the list would
be updated and maintained.
Rationale for R5:
The new requirement provides transparency regarding the criteria used by the TOP to establish
the voltage schedule. This requirement also provides a vehicle for the TOP to use appropriate
granularity when setting notification requirements for deviation from the voltage or Reactive
Power schedule. Additionally, this requirement provides clarity regarding a “tolerance band” as
specified in the voltage schedule and the control dead-band in the generator’s excitation
system.
Voltage schedule tolerances are the bandwidth that accompanies the voltage target in a voltage
schedule, should reflect the anticipated fluctuation in voltage at the Generation Operator’s
facility during normal operations, and be based on the TOP’s assessment of N‐1 and credible N‐
2 system contingencies. The voltage schedule’s bandwidth should not be confused with the
control dead‐band that is programmed into a Generation Operator’s automatic voltage
regulator’s control system, which should be adjusting the AVR prior to reaching either end of
the voltage schedule’s bandwidth.
Rationale for R6:
Although tap settings are first established prior to interconnection, this requirement could not
be deleted because no other standard addresses when a tap setting must be adjusted. If the tap
setting is not properly set, then the amount of VARs produced by a unit can be affected.

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