PDCWG 2/1/2012

January 2012 Generation Resource Energy and Regulation Deployment Performance

2

Month-to-Month NON-IRR GREDP – Energy Deployments

Resources below 85% threshold

• 4 repeat resources from December 2011• * Same Jointly Owned Resource

QSE Name Resource Name Fuel TypeTotal Intervals Passed

Total Intervals Scored

Std Dev(GREDP MW)

GREDP Monthly Score

QSE1 <RESOURCE NAME> GSREH 80 98 6.43 81.63QSE2 <RESOURCE NAME> CLLIG * 555 759 11.85 73.12QSE3 <RESOURCE NAME> GSREH 2 10 12.17 20QSE4 <RESOURCE NAME> SCLE90 16 19 3.23 84.21QSE4 <RESOURCE NAME> SCLE90 20 24 4.64 83.33QSE4 <RESOURCE NAME> CC 34 44 9.2 77.27QSE4 <RESOURCE NAME> SCLE90 7 11 7.53 63.64QSE4 <RESOURCE NAME> SCLE90 2 5 10.54 40QSE5 <RESOURCE NAME> CLLIG * 886 1,178 4.52 75.21

3

Month-to-Month NON-IRR GREDP – Regulation Deployments

Bottom 10 Resources during Regulation intervals *

* Please note that only one Resource here did not pass overall GREDP measure.

QSE Name Resource Name Fuel Type Total Intervals Passed

Total Intervals Scored

Std Dev(GREDP MW)

GREDP Monthly Score

QSE1 <RESOURCE NAME> GSREH 34 39 3.73 87.18QSE2 <RESOURCE NAME> CC 1,723 1,809 4.45 95.25QSE2 <RESOURCE NAME> CC 877 1,013 5.34 86.57QSE3 <RESOURCE NAME> CC 9 10 2.67 90QSE4 <RESOURCE NAME> CC 276 289 10.72 95.5QSE5 <RESOURCE NAME> GSREH 42 44 3.44 95.45QSE5 <RESOURCE NAME> GSREH 139 149 21.83 93.29QSE5 <RESOURCE NAME> GSREH 129 141 5.06 91.49QSE5 <RESOURCE NAME> GSREH 7 10 11.56 70QSE6 <RESOURCE NAME> CC 3,978 4,248 5.46 93.64

4

Month-to-Month IRR GREDP

Resources below 95% thresholdNov-11 Dec-11 Jan-12

< 10 Intervals 16 9 2>=10<100 Intervals 12 16 7>=100<500 Intervals 4 13 2>=500 Intervals 10 7 14Weighted Averaged GREDP * 92.2% 88.9% 92.0%Average Deviation * 8.0 MWs 11.1 MWs 7.3 MWs* Includes all WGRs (not just failures)

5

January IRR Failures

QSE Name Resource Name Total Intervals Passed

Total Intervals Scored

Std Dev (ATG-Exp MW)

GREDP Monthly Score

QSE1 <RESOURCE NAME> 2,490 2,728 1.77 91.28

QSE1 <RESOURCE NAME> 1,581 1,744 4.53 90.65

QSE2 <RESOURCE NAME> 47 50 16.95 94

QSE3 <RESOURCE NAME> 1,292 1,383 7.19 93.42

QSE3 <RESOURCE NAME> 1,260 1,354 7 93.06

QSE4 <RESOURCE NAME> 7 15 11.08 46.67

QSE5 <RESOURCE NAME> 1,561 1,688 16.91 92.48

QSE6 <RESOURCE NAME> 1,414 1,500 9.35 94.27

QSE6 <RESOURCE NAME> 925 986 6.72 93.81

QSE6 <RESOURCE NAME> 50 57 7.2 87.72

QSE6 <RESOURCE NAME> 49 56 8.86 87.5

QSE6 <RESOURCE NAME> 33 43 3.64 76.74

QSE6 <RESOURCE NAME> 37 46 9.33 80.43

QSE7 <RESOURCE NAME> 0 3 1.72 0

QSE8 <RESOURCE NAME> 1,138 1,237 1.07 92

QSE8 <RESOURCE NAME> 523 637 7.48 82.1

QSE8 <RESOURCE NAME> 372 502 3.69 74.1

QSE8 <RESOURCE NAME> 147 226 18.12 65.04

QSE9 <RESOURCE NAME> 880 963 4.2 91.38

QSE9 <RESOURCE NAME> 855 957 4.9 89.34

QSE9 <RESOURCE NAME> 840 949 2.02 88.51

QSE9 <RESOURCE NAME> 834 950 2.21 87.79

QSE10 <RESOURCE NAME> 359 448 23.63 80.13

QSE10 <RESOURCE NAME> 2 5 7.73 40

QSE11 <RESOURCE NAME> 14 20 15.75 70

6

Update on WGR HSL logic

Performance when responding to curtailment ( 24 resources totaling

3039.2 MW were curtailed during the study period)

Number of QSEs (Note that some QSEs may have some

good and some bad resources)

Total WGR Capacity (MW)

BAD 5 1412.7MODERATE 3 415.2GOOD 6 836.2

Performance when NOT being curtailed and/or NOT being released from

curtailment (Note HHGT units are included as separate hence the total cap

of 10650MW)

Number of QSEs(Note that some QSEs may have

some good and some bad resources)

Total WGR Capacity (MW)

BAD 3 300.45MODERATE 8 3103.4GOOD 24 6872.6

• Communication was sent to QMWG in early January. • Analysis period was from 12/18/2011 to 12/25/2011• Mitigation Plans have been received and ERCOT is actively monitoring.

7

GREDP Scenario Analysis

* January performance of frequency excluded intervals for IRRs was 90% (2278 passed/2529 scored). The Std Dev was 8.54 MWs.

NON-IRRs (Jan-12) >= 85% < 85% % Passing 5 MW 204 60 77.27%10 MW 248 16 93.94%15 MW 259 5 98.11%5 MW - 5% 243 21 92.05%8MW - 8% (Current) 255 9 96.59%Exclusions - No Freq Dev 256 8 96.97%

IRRs (Jan-12) >= 95% < 95% % Passing 0% - 3 MW Band 28 30 48.28%5% - 3 MW Band 29 29 50.00%10% - 3MW Band 34 24 58.62%10% - 1 MW Band when BP = 0 (Current) 33 25 56.90%Exclusions - No Freq Dev * 28 30 48.28%

* January performance of frequency excluded intervals for NON-IRRs was 90% (74,406 passed/75,123 scored). The Std Dev was 2.98 MWs.

Manual HDL/LDL Override Summary

QMWG

9

Daily Summary Graph

• For this analysis, we captured unique HDL/LDL overrides– An override is considered unique if that same Resource did not

have an override within the last 10 minutes• There were 13 total unique overrides in January

– As compared to 13 in December and 17 in November

10

Daily Summary Table

DateTotal Number of

OverridesNumber of Resources

with an OverrideNumber of Unique HDL/LDL Overrides

Jan 1, 2012 0 0 0Jan 2, 2012 0 0 0Jan 3, 2012 0 0 0Jan 4, 2012 0 0 0Jan 5, 2012 0 0 0Jan 6, 2012 0 0 0Jan 7, 2012 0 0 0Jan 8, 2012 0 0 0Jan 9, 2012 0 0 0

Jan 10, 2012 0 0 0Jan 11, 2012 0 0 0Jan 12, 2012 0 0 0Jan 13, 2012 0 0 0Jan 14, 2012 24 2 2Jan 15, 2012 0 0 0Jan 16, 2012 0 0 0Jan 17, 2012 0 0 0Jan 18, 2012 0 0 0Jan 19, 2012 2 2 2Jan 20, 2012 0 0 0Jan 21, 2012 0 0 0Jan 22, 2012 0 0 0Jan 23, 2012 0 0 0Jan 24, 2012 0 0 0Jan 25, 2012 0 0 0Jan 26, 2012 0 0 0Jan 27, 2012 0 0 0Jan 28, 2012 0 0 0Jan 29, 2012 0 0 0Jan 30, 2012 46 2 4Jan 31, 2012 260 6 5

11

Reasons for Manual HDL/LDL Overrides

• An override is considered unique if that same Resource did not have an override within the last 10 minutes

• The “Other” reason given was QSE requested testing

• Congestion concerns were a result of a Resource not following base-points