Var-501-wecc-1

WECC Standard VAR-501-WECC-1 — Power System Stabilizer
A. Introduction
1. Title:

Power System Stabilizer (PSS)

2. Number:

VAR-501-WECC-1

3. Purpose:

To ensure that Power System Stabilizers (PSS) on synchronous generators
shall be kept in service.

4. Applicability
4.1. Generator Operators
5. Effective Date: On the first day of the first quarter, after applicable regulatory approval.
B. Requirements
R1.

Generator Operators shall have PSS in service 98% of all operating hours for
synchronous generators equipped with PSS. Generator Operators may exclude hours
for R1.1 through R1.12 to achieve the 98% requirement. [Violation Risk Factor:
Medium] [Time Horizon: Operations Assessment]
R1.1.

The synchronous generator operates for less than five percent of all hours during
any calendar quarter.

R1.2.

Performing maintenance and testing up to a maximum of seven calendar days
per calendar quarter.

R1.3.

PSS exhibits instability due to abnormal system configuration.

R1.4.

Unit is operating in the synchronous condenser mode (very near zero real power
level).

R1.5.

Unit is generating less power than its design limit for effective PSS operation.

R1.6.

Unit is passing through a range of output that is a known “rough zone” (range in
which a hydro unit is experiencing excessive vibration).

R1.7.

The generator AVR is not in service.

R1.8.

Due to component failure, the PSS may be out of service up to 60 consecutive
days for repair per incident.

R1.9.

Due to a component failure, the PSS may be out of service up to one year
provided the Generator Operator submits documentation identifying the need
for time to obtain replacement parts and if required to schedule an outage.

R1.10. Due to a component failure, the PSS may be out of service up to 24 months
provided the Generator Operator submits documentation identifying the need
for time for PSS replacement and to schedule an outage.
R1.11. The synchronous generator has not achieved Commercial Operation.
R1.12. The Transmission Operator directs the Generator Operator to operate the
synchronous generator, and the PSS is unavailable for service.
R2.

Generator Operators shall have documentation identifying the number of hours
excluded for each requirement in R1.1 through R1.12. [Violation Risk Factor:
Low] [Time Horizon: Operations Assessment]

C. Measures
M1. Generators Operators shall provide quarterly reports to the compliance monitor and have
evidence for each synchronous generator of the following:
Adopted by Board of Trustees: October 29, 2008

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WECC Standard VAR-501-WECC-1 — Power System Stabilizer
M1.1

The number of hours the synchronous generator was on line.

M1.2

The number of hours the PSS was out of service with generator on line.

M1.3

The PSS in service percentage

M1.4

If excluding PSS out of service hours as allowed in R1.1 through R1.12,
provide:
M1.4.1 The number of hours excluded, and
M1.4.2 The adjusted PSS in-service percentage.

M2. If excluding hours for R1.1 through R1.12, provide:
M2.1

The date of the outage

M2.2

Supporting documentation for each requirement that applies

D. Compliance
1. Compliance Monitoring Process
1.1

Compliance Monitoring Responsibility

1.2

Compliance Enforcement Authority
Compliance Monitoring Period
Compliance Enforcement Authority may use one or more of the following methods
to assess compliance:
- Reports submitted quarterly
- Spot check audits conducted anytime with 30 days notice
- Periodic audit as scheduled by the Compliance Enforcement Authority
- Investigations
- Other methods as provided for in the Compliance Monitoring Enforcement
Program
The Reset Time Frame shall be a calendar quarter.

1.3

Data Retention
The Generator Operators shall keep evidence for Measures M1 and M2 for three
years plus current year, or since the last audit, whichever is longer.

1.4

Additional Compliance Information
1.4.1

The sanctions shall be assessed on a calendar quarter basis.

1.4.2

If any of R1.2 through R1.12 continues from one quarter to another, the
number of days accumulated will be the contiguous calendar days from the
beginning of the incident to the end of the incident. For example, in R1.8
if the 60 day repair period goes beyond the end of a quarter, the repair
period does not reset at the beginning of the next quarter.

1.4.3

When calculating the adjusted in-service percentage, the PSS out of service
hours do not include the time associated with R1.1 through R1.12.

1.4.4

The standard shall be applied on a generating unit by generating unit basis
(a Generator Operator can be subject to a separate sanction for each noncompliant synchronous generating unit or to a single sanction for multiple
machines that operate as one unit).

Adopted by Board of Trustees: October 29, 2008

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WECC Standard VAR-501-WECC-1 — Power System Stabilizer

2. Violation Severity Levels
2.1. Lower: There shall be a Lower Level of non-compliance if the following condition exists:
2.1.1.

PSS is in service less than 98% but at least 90% or more of all hours during
which the synchronous generating unit is on line for each calendar quarter.

2.2. Moderate: There shall be a Moderate Level of non-compliance if the following condition
exists:
2.2.1.

PSS is in service less than 90% but at least 80% or more of all hours during which
the synchronous generating unit is on line for each calendar quarter.

2.3. High: There shall be a High Level of non-compliance if the following condition exists:
2.3.1.

PSS is in service less than 80% but at least 70% or more of all hours during which
the synchronous generating unit is on line for each calendar quarter.

2.4. Severe: There shall be a Severe Level of non-compliance if the following condition
exists:
2.4.1.

PSS is in service less than 70% of all hours during which the synchronous
generating unit is on line for each calendar quarter.

3. Violation Severity Levels for R2
3.1. Lower: There shall be a Lower Level of non-compliance if documentation is incomplete
with any requirement R1.1 through R1.12.
3.2. Moderate: There shall be a Moderate Level of non-compliance if the Generator Operator
does not have documentation to demonstrate compliance with any requirement R1.1
through R1.12.
3.3. High: Not Applicable
3.4. Severe: Not Applicable
E. Regional Differences
Version History — Shows Approval History and Summary of Changes in the Action Field
Version

Date

Action

1

April 16, 2008

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

1

April 21, 2011

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

Adopted by Board of Trustees: October 29, 2008

Change Tracking

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