January 2011 GREDP Performance Summary

1. January 2011 GREDP Performance Summary QMWG February 7, 2011

2. Month-to-Month GREDP Summary Overall Similar performance between December and January NON-IRRs 288 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 IRRs 19 Passing Resources 36 Failing Resources - All Resources scored < 1700 intervals - 20% of the intervals/month

3. IRR GREDP Performance by Intervals Scored Summary Both 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

4. NON-IRR GREDP Performance by Intervals Scored Summary Both graphs plot the total intervals scored and the GREDP Monthly score by Resource for NON-IRRs Less of a trend of poor performance for Resources scored for very few intervals

5. GREDP Performance by Unit Capability

6. Non-Spin Energy Deployment Performance – January 2011 GREDP Deployment Score Total Intervals Scored

7. Things to Remember for GREDP • NON-IRRs • NON-IRR GREDP Score • GREDP MW = ABS(ATG-AEPFR-ABP-ARI) • GREDP % = ABS((ATG-AEPFR)/(ABP+ARI)-1)*100 • Threshold – GREDP MW < 8MW or GREDP % < 8% • IRRs • IRR GREDP Score • GREDP MW – ATG-Expected MW • GREDP % = ((ATG-AEPFR)/(ABP+ARI)-1)*100 • Resource must be curtailed (HSL-BP > 2MW) • ATG – Expected MW >= 1 MW • Threshold – GREDP % < 10% • Common Requirements for Scoring • “ON” Resource Status • Net MW >= LSL

8. GREDP Exclusions Exclusions 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. 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”. 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. 

9. Summary Common Issues 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. 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. 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.