QMWG February 7, 2011

January 2011 GREDP Performance Summary

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Month-to-Month GREDP Summary

OverallSimilar performance between December and January

NON-IRRs288 Passing Resources (98%)7 Failing Resources (10 less than January) - 6 Resources scored < 500 intervals - 6% of the intervals/month - 1 Resource scored > 7000 intervals - 90% of the intervals/month

IRRs19 Passing Resources 36 Failing Resources - All Resources scored < 1700 intervals - 20% of the intervals/month

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IRR GREDP Performance by Intervals Scored

SummaryBoth graphs plot the total intervals scored and the GREDP Monthly score by Resource for IRRs

Trend of poor performance for Resources scored (and curtailed) for very few intervals

Jump in performance for IRRs scored for > 200 intervals per month

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NON-IRR GREDP Performance by Intervals Scored

SummaryBoth graphs plot the total intervals scored and the GREDP Monthly score by Resource for NON-IRRs

Less of a trend of poorperformance for Resourcesscored for very few intervals

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GREDP Performance by Unit Capability

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Non-Spin Energy Deployment Performance – January 2011

GREDP Deployment Score

Total Intervals Scored

Deployment Time Recall TimeResources Passed

Resource Failed

January 5th 6:20:05PM January 5th 8:04:26 PM 25 4January 7th 6:47:51 AM January 7th 7:53:25 AM 33 10January 21st 11:32:09 PM January 22nd 9:00:24 AM 55 4January 22nd 12:22:41 AM January 22nd 5:47:49 AM 25 0January 27th 6:41:07 AM January 27th 8:29:39 AM 56 8

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Things to Remember for GREDP

NON-IRRs1.NON-IRR GREDP Score

1. GREDP MW = ABS(ATG-AEPFR-ABP-ARI)2. GREDP % = ABS((ATG-AEPFR)/(ABP+ARI)-1)*100

2.Threshold – GREDP MW < 8MW or GREDP % < 8%

IRRs1.IRR GREDP Score

1. GREDP MW – ATG-Expected MW2. GREDP % = ((ATG-AEPFR)/(ABP+ARI)-1)*100

2.Resource must be curtailed (HSL-BP > 2MW)3.ATG – Expected MW >= 1 MW4.Threshold – GREDP % < 10%

Common Requirements for Scoring1.“ON” Resource Status2.Net MW >= LSL

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GREDP Exclusions

Exclusions1. Emergency Base Point Exclusion – Where the interval is anywhere between the

emergency base points’ declare and recall time. If an EBP extends across 1 or more intervals and effects at least one second of the interval, all intervals affected should be to ‘Y’ FOR ALL RESOURCES in the intervals.

2. Frequency Deviation/Forced Outage Exclusion – When there is a frequency deviation and a forced outage occurs (in ERCOT’s Forced Outage detector) between the frequency deviation time minus 10 seconds and the frequency deviation time plus 1 minute, correlate the events and set the interval to ‘Y’ for all resources for the occurring interval as well as the following 4 intervals. This would set the value to ‘Y’ for a total of 5 intervals per occurrence. Ensure that an event can happen across loading periods by processing an overlap in time to capture events that span more than one “Day”.

3. ERCOT Exclusion – This would occur when SCED is missing an interval.  ERCOT will backfill it with last good interval, but exclude the interval from GREDP scoring.  This is intended for very rare situation like natural disasters. 

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Summary

Common Issues1.QSEs representing IRRs commented that they have difficultly recognizing when they are being curtailed. Under curtailment, they must follow specific Base Points from ERCOT, but keep their HSL at the possible output of the IRR if not curtailed. MPs have requested a “Curtailment Flag” so that they would know exactly when their being curtailed.

2.Also, because IRRs are only scored during a curtailment, they are scored a relatively low number of intervals. The average number of intervals scored was approximately 3% of the total intervals for IRRs.

3.The GREDP score does not give a magnitude of error in the monthly score. The monthly score is based on the count of passed versus failed intervals in a month.