Colorado Energy Management – MPC (COMPC), Docket No. RC13-6-000 (February 28, 2013)
Reliability Standard: VAR-501-WECC-1
Requirement: 1
Region: WECC
Issue: COMPC, a GOP, filed two self-reports (November 2012 and January 2013) explaining that after a start-up of a gas turbine, employees mistakenly reported to the TOP that the Power System Stabilizer (PSS) for the turbine was in service and active when, in fact, the PSS had changed to manual mode and was not active. Operators realized the error and switched the PSS to automatic mode, but the mistake was not noticed for eight hours, and therefore, the TOP was not notified within the 30-minute timeframe required nor was the PSS in service for at least 98% of all operating hours during Q4 2012 as required.
Finding: The issue was deemed to pose minimal risk to BPS reliability and not serious or substantial risk. The risk to BPS operations was mitigated because COMPC maintained the TOP's established voltage schedule during the relevant time period. Also, the automatic voltage regulator connected to the relevant turbine was in automatic mode and would have responded as designed to prevent any negative consequences that could have been caused by an increased voltage level or reactive flow. COMPC's internal procedures also are set so that once the issue was found, the TOP was notified immediately of the change and length of the status change. Also, COMPC is only a peaking plant so any impact would be minimal to the TOP's service.
Find, Fix and Track Entity, FERC Docket No. RC12-8 (February 29, 2012)
Reliability Standard: VAR-501-WECC-1
Requirement: R1
Region: WECC
Issue: WECC found that one of FFT Entity's units operated with its Power System Stabilizers (PSS) out of service for approximately 22 hours. The relevant unit operated with the PSS in service between 95% and 98% of the time during the fourth quarter.
Finding: WECC found that the issue constituted only a minimal risk to the BPS since the relevant unit operated with its PSS in service for the vast majority of the calendar quarter (which reduces the probability of FFT Entity experiencing unnecessary loss of a facility during a transient event). In this situation, the automatic voltage regulators also functioned to protect the unit by allowing it to respond to changes in voltage. In addition, the relevant unit represented only a small portion of FFT Entity's generation (and an even smaller portion of FFT Entity's total generation capacity available).
High Desert Power Project, LLC, FERC Docket No. RC12-11 (April 30, 2012)
Reliability Standard: VAR-501-WECC-1
Requirement: R1
Region: WECC
Issue: High Desert Power Project, LLC (HDPP), as a GO, self-reported that from November 17, 2011 through November 20, 2011, the PSS on its combustion turbine unit 1 was turned off for 62.6 hours (out of a total run time for the unit of 996.18 hours). Therefore, HDPP's PSS was only in service for 93.7% of unit's operating time for the fourth quarter of 2011, which is below the mandated 98% required level for in-service time.
Finding: WECC found that this issue constituted only a minimal risk to the BPS. During the time HDPP's PSS was out of service, the automatic voltage regulator (AVR) was in service, which allowed the generator to effectively respond to any voltage deviation. Furthermore, the PSS on the unit was operating for the majority of the fourth quarter of 2011, reducing the chance of an unnecessary loss of a facility during an event.
Las Vegas Power Company, LLC (LVPC), Docket No. RC12-14 (July 30, 2012)
Reliability Standard: VAR-501-WECC-1
Requirement: 1
Region: WECC
Issue: LVPC, in its role as a GOP, submitted a self-report in March 2012 explaining that the PSS installed on a synchronous generator had not reached the required operating standard of 98% availability. During a control system component failure event, the PSS was in the off mode during the repairs which took place during January 2012. Subsequent availability calculations showed that the PSS was in the required mode and available only 95.84% of total operating hours.
Finding: The issue was deemed by WECC to pose minimal risk to BPS reliability because the PSS was only in the off mode for about 25 hours. Also, the relevant generator has a 165 MW capacity only and is housed at a facility that has two other generators available that could provide 395 MW of output, and another 2,000 MW of generation is available within a five-mile radius. Due to the amount of generation available with PSS in the immediate area, WECC determined that system damping needs would be minimal and other units would compensate for any issue caused by the subject unit.
Wood Group Power Operations (WGCS), Docket No. RC12-13 (June 29, 2012)
Reliability Standard: VAR-501-WECC-1
Requirement: R1
Region: WECC
Issue: WGCS self-reported an issue with VAR-501-WECC-1 R1 because after a system start-up, the Power System Stabilizers (PSS) on its generator controls were not enabled leading to the failure by WGCS to make certain that its PSS was operational for 98% of all operating hours. The event occurred during the first quarter of 2012.
Finding: The issued was deemed by WECC to pose minimal risk to BPS reliability because the PSS was in operation 90-95% of the time during the relevant time period. Also, while the PSS was disabled, the automatic voltage regulator did operate all units at 50 MW meaning those units could respond to system deviations. Also WGCS is a peaking facility controlled by its TOP. The time period the PSS was not in service was only 14.75 hours during the quarter.
