NorthWestern Corporation (NWC), Docket No. RC12-12 (May 30, 2012)
Reliability Standard: TOP-007-WECC-1
Requirement: R2
Region: WECC
Issue: NWC, in its roles as a BA, TOP, TO, GO, LSE and TP, self-reported that on November 22, 2011, WECC Path 18 was overscheduled by five MW. NWC is the Path Operator for Path 18. WECC determined that the issue was caused by a change made by mistake in a User Defined Interface (AMPS) used to watch activity on Path 18. The change temporarily removed the real time hour ahead wind schedules from the AMPS total allowing real time schedules to be implemented causing a 5 MW overschedule.
Finding: The issue was found to pose minimal risk to BPS reliability because the System Operating Limit on Path 18 was 337 and therefore the overschedule of 5 MW was less than 2% of the SOL and actual flows never exceeded the Operating Transfer Capability Limits during the event. And, the duration of the violation was an hour and was corrected as soon as it was discovered.
Western Area Power Administration – Rocky Mountain Region (WACM), Docket No. RC12-13 (June 29, 2012)
Reliability Standard: TOP-007-WECC-1
Requirement: R2
Region: WECC
Issue: WACM, in its role as a TOP, submitted a self-report of possible non-compliance with the Reliability Standard because it scheduled power over the System Operating Limit (SOL) on a major WECC path despite the fact that schedules for the following hour had been finalized.
Finding: The issued was deemed by WECC to pose minimal risk to BPS reliability because the SOL was only exceeded by less than 4% for a short time period.
