VAR-501-WECC-1: Power System Stabilizer (PSS)

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

Applicability
Generator Operators

Effective Date
On the first day of the first quarter, after applicable regulatory approval.

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]

Measures
M1. Generators Operators shall provide quarterly reports to the compliance monitor and have evidence for each synchronous generator of the following:

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


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