1. Comparison of New Load Profile Models 14-Month Models vs 21-Month Models ERCOT Load Profiling Staff

2. 2 Background Information ERCOT staff discovered error with LRS analysis –Error was misclassification of some ESIIDs with profile type migrations occurring since the time of sample selection –Misclassification resulted in improper sample post- stratification Models built from LRS means were incorrect LRS analysis was corrected

3. 3 Background Information New models developed Original analysis covered 14 months (Nov ‘04 – Dec ‘05) New analysis covered 21 months (Nov ‘04 – July ‘06) Intent of this analysis is to examine and quantify the differences between the 14-month and 21-month models

4. 4 Comparison of New Load Profile Models 14-Month Models vs 21-Month Models

5. Misclassifications for BUSHILF_NCENT

6. 6 Strata Impacted by Misclassification for BUSHILF_NCENT

7. PROFILE TYPE PEAK & AVERAGE DAY MINOR DIFFERENCES

8. 8 RESLOWR_NCENT MONTHLY PEAK DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

9. 9 RESLOWR_NCENT MONTHLY AVERAGE DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

10. 10 RESHIWR_COAST MONTHLY PEAK DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

11. 11 RESHIWR_COAST MONTHLY AVERAGE DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

12. 12 BUSLOLF_SCENT MONTHLY PEAK DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

13. 13 BUSLOLF_SCENT MONTHLY AVERAGE DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

14. 14 BUSNODEM_NCENT MONTHLY PEAK DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

15. 15 BUSNODEM_NCENT MONTHLY AVERAGE DAYS – ENTIRE PERIOD 14 Month Model 21 Month Model Minor Differences

16. PROFILE TYPE PEAK & AVERAGE DAY SOME DIFFERENCES

17. 17 BUSMEDLF_FWEST MONTHLY PEAK DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model

18. 18 BUSMEDLF_FWEST MONTHLY AVERAGE DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.4%

19. 19 BUSMEDLF_SOUTH MONTHLY PEAK DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model

20. 20 BUSMEDLF_SOUTH MONTHLY AVERAGE DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.4%

21. 21 BUSHILF_COAST MONTHLY PEAK DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model

22. 22 BUSHILF_COAST MONTHLY AVERAGE DAYS – ENTIRE PERIOD 14 Month Model Scaled 14 Month 21 Month Model Some Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.9%

23. 23 BUSHILF_SOUTH MONTHLY PEAK DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model

24. 24 BUSHILF_SOUTH MONTHLY AVERAGE DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.9%

25. 25 BUSHILF_WEST MONTHLY PEAK DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model

26. 26 BUSHILF_WEST MONTHLY AVERAGE DAYS – ENTIRE PERIOD Some Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.6%

27. PROFILE TYPE PEAK & AVERAGE DAY MAJOR DIFFERENCES

28. 28 BUSMEDLF_NCENT MONTHLY PEAK DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model

29. 29 BUSMEDLF_NCENT MONTHLY AVERAGE DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.7%

30. 30 BUSHILF_EAST MONTHLY PEAK DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model

31. 31 BUSHILF_EAST MONTHLY AVERAGE DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.1%

32. 32 BUSHILF_NCENT MONTHLY PEAK DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model

33. 33 BUSHILF_NCENT MONTHLY AVERAGE DAYS – ENTIRE PERIOD Major Differences 14 Month Model Scaled 14 Month 21 Month Model Scaled 14 month vs 21 month R 2 = 99.7%

34. 34 Findings….. 14-month and 21-month models show only minor differences in 40 of the 48 profile type / weather zone combinations Of the 8 profile type / weather zone combinations with differences only 3 had major differences Scaled 14-month models were virtually identical to the 21- month models… differences were mostly magnitude and not shape related Repeating the ERCOT test settlement runs is not likely to result in different findings regarding the Option 3-M transition recommendation