1. Joel Koepke, P.E. ERCOT Operations Support Engineer ERCOT Experiences During Summer 2011

2. 2 Objectives Identify weather and nature challenges Identify variables leading to EEAs Identify mitigating actions of August 4 th EEA Identify outlook and changes for Summer 2012

3. 3 Weather Extremes

4. 4 High-Pressure System

5. 5 Record Drought

6. 6 West Texas fires in March through May Approximate cost of Transmission equipment damage and maintenance FireContamination $3,994,264$1,340,940 Approximate cost of Distribution equipment damage and maintenance FireContamination $1,500,000$313,780 Approximate Cost of Congestion Day-Ahead MarketReal-Time Market $2,170,840.56$1,127,056.03 Wildfires

7. 7 Tested Situational Awareness Tools

8. 8 Record Heat

9. 9 Average Min/Max Load Values June – August of 2009 - 2011

10. 10 Instantaneous Summer Peak

11. Summer Energy Emergency Alerts

12. 12 1 2A 2B 3 2011 EEA Procedure

13. August 2011 SundayMondayTuesdayWednesdayThursdayFridaySaturday 3112 EEA 1 3 EEA 1 4 EEA 2B 5 EEA 1 6 78910111213 14151617181920 212223 EEA 1 24 EEA 2A 252627 28293031123 June 2011 SundayMondayTuesdayWednesdayThursdayFridaySaturday 2627 EEA 1 283456 2011 Summer Energy Emergency Alerts

14. 14 PRC Physical Responsive Capability (PRC) –A representation of the total amount of system wide On-Line capability that has a high probability of being able to quickly respond to system disturbances

15. 15 June 27 th EEA Highlights 3 unit trips in less than 2 hours –Total of 1,800 MW Large wind decline –Drop of 4,200 MW in 4 hours Large load increase –Increase of 4,000 MW in 2 hours Below 2,300 MW of Reserves for 1 minute EEA lasted for 1 hour and 25 minutes

16. 16 June 27 th EEA - Frequency

17. 17 June 27 th EEA- Wind and Load Unit Trips

18. 18 June 27 th EEA – Physical Responsive Capability

19. August 2011 SundayMondayTuesdayWednesdayThursdayFridaySaturday 3112 EEA 1 3 EEA 1 4 EEA 2B 5 EEA 1 6 78910111213 14151617181920 212223 EEA 1 24 EEA 2A 252627 28293031123

20. 20 August Peak Loads 8/3: Record Peak

21. 21 Variables Affecting Physical Responsive Capability –Online generation –System load magnitude –Resource outages and derates –Wind output –DC tie imports

22. 22 Outaged Resource Capacity – 2011

23. 23 Outaged Resource Capacity – August

24. 24 Outaged Resource Capacity – Week View

25. Geographic Wind Regions

26. 26 Average Summer Wind Contribution

27. 27 Average EEA Wind Contribution

28. 28 Summer vs. EEA Comparison – Total Wind

29. 29 Summer vs. EEA Comparison – West Wind

30. 30 Summer vs. EEA Comparison – South Wind

31. 31 Summer vs. EEA Comparison – ERCOT Load

32. 32 DC-Tie Imports: August 2 nd – August 5th

33. Load Resources and EILS deployed August 4 th EEA Level 2B

34. 34 1,392 MW Non- Spin deployed August 04, 2011 - EEA Level 2B Issued Watch Reserves below 2,500 MW 1:25 PM Cancelled Advisory 10:17 PM Note: Watch also include: Qualified Scheduling Entity Hotline Call Transmission Operator Hotline Call Postings on the Market Information System and ERCOT website Cancelled Watch Issued OCN  Projected reserve capacity shortage for hours 14:00 through 21:00 0:06 AM 12:38 PM Issued Advisory Reserves below 3,000 MW 2:32 PM6:09 PM Cancelled OCN ERCOT ran out of regulation and issued manual Responsive Reserve deployment 2:15 PM 8:38 PM 3:44 PM Load Resources Recalled Move to EEA 2A From EEA 2B Move to EEA 1 From EEA 2A 5:53 PM6:52 PM8:49 PM 1:45 PM EILS Recalled 4:05 PM EILS deployment Business Hours 3 A UGUST 4 W ATCH FOR EXTREME HEAT STILL IN EFFECT

35. 35 ERCOT Load, Wind, and PRC 8/4/2011 00:00–12:00

36. 36 Outaged Capacity 8/4/2011 00:00–12:00

37. 37 ERCOT Load, Wind, and PRC 8/4/2011 12:00–24:00

38. 38 Outaged Capacity 8/4/2011 12:00–24:00

39. 39 1,039 MW 594 MW 229 MW 216 MW ERCOT had a max import of 1,039 MW across the DC Ties  East DC Tie= 594 MW  North DC Tie= 216 MW  South DC Tie=229 MW DC Tie Imports: 8/4/2011

40. 40 ERCOT Load, Online Capacity, Offline Non-Spin and Net DC flow

41. 41 Summer 2012 Outlook

42. 42 ERCOT CDR - Report on the Capacity, Demand, and Reserves in the ERCOT Region Long-term planning tool Uses normalized assumptions –Normal weather basis –Does not include Resource outages Summer Summary released in December of 2011. –Peak Demand – 66,195 MW 64,618 MW firm load 738 MW of firm load added since June CDR –Available Capacity – 72,444 MW –Reserve Margin – 12.11%

43. 43 Seasonal Assessment of Resource Adequacy (SARA) New report Evaluates near-term Reserve adequacy –Uses more recent seasonal climate forecast –Accounts for specific events (e.g. Drought) Evaluate the range of reserves usage in a deterministic manner –Uses of reserves: Higher peak demands due to above normal weather Forced generation outages Planned generation outages Atypical issues like drought Lower wind availability Determines the likelihood of Reserves dropping below the 2,300 MW threshold.

44. 44 Emergency Interruptible Load Service (EILS) Proposed Changes –Allow Distributed Generation and unregistered generation to participate New capacity –Remove the 1 MW minimum offer Improve QSE flexibility Increase participation –Explore the possibility of a 30-min product Increase participation

45. Questions?