1. 1 EEA Workshop 3 April 2, 2015 4/3/2015For the purpose of discussion only

2. 2 Overview 1.Recap of EEA Workshop 1 2.Recap of EEA Workshop 2 3.Proposed Changes 1.Physical Responsive Capability (PRC) 2.Energy Emergency Alert (EEA) 4/3/2015For the purpose of discussion only

3. 3 EEA Workshop 1 Recap Reviewed background on EEA –NERC Standard –Single vs Multiple Balancing Authority (BA) Interconnection Physical Responsive Capability (PRC) –Definition and Intent –Current PRC calculation –Changes to the PRC in near future Current Procedures and Triggers History of EEA –Summarize EEA historical information –Recent weather challenges were discussed 4/3/2015For the purpose of discussion only

4. 4 EEA Workshop 1 Recap Reviewed Current Ancillary Services –Responsive Reserve Service –Regulation Service –Non-Spinning Reserve Service Managing Constraints in EEA –Re-Evaluation of SOLs during EEA2 and EEA3 –Management of stability limits and IROLs during EEA Note : Presentation for EEA Workshop 1 can be found at the link below http://www.ercot.com/calendar/2014/04/20140422-EEAWorkshop 4/3/2015For the purpose of discussion only

5. 5 EEA Workshop 2 Recap Reviewed Current EEA Practices –Current EEA levels and triggers –EEA 1 Comparisons between Aug 3, 2011 and January 18, 2014 Dynamic Simulations –Different scenarios were studied including tripping of a largest unit under EEA 3 condition –Minimum PFR Needs identified for EEA 3 conditions for different system load conditions Reviewed Physical Responsive Capability –Definition and intent of PRC –Current PRC calculations and its limitations –Review proposed changes to the PRC calculation 4/3/2015For the purpose of discussion only

6. 6 EEA Workshop 2 Recap Managing Constraints in EEA 2 & 3 –NPRR 642 endorsed by the 03/26/2015 TAC meeting Types of EEA events were discussed since 2008 Note : Presentation for EEA Workshop # 2 can be found at the link below http://www.ercot.com/calendar/2014/06/20140619-EEAWorkshop 4/3/2015For the purpose of discussion only

7. 7 EEA Steps Maintain 2,300 MW of PRC reserves 1 2 3 Maintain 1,750 MW of PRC reserves. Interrupt loads providing Responsive Reserve Service. Interrupt loads providing Emergency Response Service (ERS). Maintain System frequency at or above 59.8 Hz and instruct TSPs and DSPs to shed firm load in rotating blocks. EEA procedure in the ERCOT Protocols defined by levels 4/3/2015For the purpose of discussion only

8. 8 EEA 1 Comparison August 3 2011 VS. January 18 2014 August 3 2011 –Cause : diminishing reserves –PRC below 2300 MW for ~3 hours –Contingency Reserves (Non-Spin) deployed –Event Duration (PRC below 3000 MW): ~6 hours 4/3/2015For the purpose of discussion only

9. 9 EEA 1 Comparison August 3 2011 VS. January 18 2014 January 18 2014 –Cause: Unit trip –PRC below 2300 MW for ~ 30 minutes –Frequency recovered in 45 seconds –Contingency Reserves deployed and quickly recalled –Event Duration (PRC below 3000 MW): ~1 hour 4/3/2015For the purpose of discussion only

10. 10 EEA 1 Comparison EEA 1 DeclaredEEA 1 Terminated 4/3/2015For the purpose of discussion only

11. 11 EEA 1 Comparison August 3 2011 VS. January 18 2014 Observations: –The August 2011 event was a true capacity shortage condition Low capacity, sufficient frequency-responsive MW –The January 2014 event was a short-duration, system recovery to a disturbance condition Sufficient capacity, low frequency-responsive MW 4/3/2015For the purpose of discussion only

12. 12 EEA 1 Comparison August 3 2011 VS. January 18 2014 Observations: –During the January 18 2014 event, PRC dipped below 2300 MW twice. Load Resources have 3 hours to come back when recalled, and if the LRs had restored sooner, the second drop may have been avoided. Similarly, if another disturbance had occurred during this event, there may not have been enough frequency-responsive reserves for that next contingency 4/3/2015For the purpose of discussion only

13. 13 Dynamic Simulation 4/3/2015For the purpose of discussion only

14. 14 Scenarios SC1: Only System Inertia (and natural load damping) SC2: Minimum PFR needs without FFR SC3: Frequency response at different PFR and FFR reserves under High Wind Low Load condition SC4: Under EEA 3 condition, frequency response with/without PFR after tripping one largest unit 4/3/2015For the purpose of discussion only

15. 15 SC4: Frequency Response, Net Load = 65 GW Net Load = 65 GW, Generation Trip 1350 MW 1---: PFR = 1250 2---: PFR = 900 3---: PFR = 600 4---: PFR = 300 5---: PFR = 100 with UFLS 4/3/2015For the purpose of discussion only

16. 16 SC4: Frequency Response, Net Load = 35 GW Net Load = 35 GW, Generation Trip 1350 MW 1---: PFR = 1400 2---: PFR = 900 3---: PFR = 600 with UFLS 4/3/2015For the purpose of discussion only

17. 17 SC4: Frequency Response, Load = 67 GW Load = 67 GW, 500 MW Load Ramp + One STP Trip 1---: PFR = 1250 2---: PFR = 900 3---: PFR = 600 4---: PFR = 300 with UFLS 5---: PFR = 100 with UFLS 3---: PFR = 600, ~59.91 Hz 3---: PFR = 600, ~59.91 Hz 4/3/2015For the purpose of discussion only

18. 18 SC4: Frequency Response, Load = 36 GW Load = 36 GW, 500 MW Load Ramp then Trip 1350 MW generation 1---: PFR = 1400 2---: PFR = 900 with UFLS 3---: PFR = 600 with UFLS 1---: PFR = 1400, ~59.93 Hz 1---: PFR = 1400, ~59.93 Hz 4/3/2015For the purpose of discussion only

19. 19 Physical Responsive Capability 4/3/2015For the purpose of discussion only

20. 20 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. 1.Conventional Generation Resources and Controllable Load Resources maximum contribution to PRC is limited to 20% of their HSL Why 20%? The Generator with a governor droop setting of 5% will provide 20% of its HSL as Governor Response if Frequency drops to 59.40 Hz from 60.00 Hz. 2.Hydro Resources operating under synchronous condenser fast response mode can contribute their full HSL*RDF towards PRC (full response within 20 seconds) 3.Non-Controllable Load Resources providing RRS is 100% counted towards PRC. (full response within 0.5 seconds) 4/3/2015For the purpose of discussion only

21. 21 Example 1 – Non-Responsive PRC HSL = 1017 MW 4/3/2015For the purpose of discussion only

22. 22 Example 2– Non-Responsive PRC HSL = 555 MW 4/3/2015For the purpose of discussion only

23. 23 Example 3 – Non-Responsive PRC HSL = 563 MW 4/3/2015For the purpose of discussion only

24. Proposed Changes 1.Calculate PRC after removing the Non-Frequency Responsive Capacity (NFRC)  NPRR-527  Explain the new PRC calculation  Examples of new vs existing PRC calculations 2.Review the proposed EEA changes  Current and Proposed EEA Level 3 Triggers and Objectives  Current and Proposed EEA Level 2 Triggers and Objectives 4/3/2015 For the purpose of discussion only

25. NPRR-527 NPRR 527 “Required Combined Cycle Telemetry for Operational Awareness and PDCWG Analysis” was implemented 11/1/2014 4/3/2015For the purpose of discussion only

26. 26 Proposed Changes to PRC calculation Lower the HSL of Combined Cycle Resources used for PRC1 calculation by telemetered NFRC Min(Max((RDF*(HSL-NFRC) – Actual Net Telemetered Output)i, 0.0), 0.2*RDF*(HSL-NFRC)i), PRC1* = *where the included On-Line Generation Resources do not include WGRs, nuclear Generation Resources, or Generation Resources with an output less than or equal to 95% of telemetered LSL or with a telemetered status of ONTEST, STARTUP, or SHUTDOWN. 4/3/2015For the purpose of discussion only

27. 27 New vs Existing PRC Calculation The following slides show the effects of the proposed NPRR to remove non-frequency responsive capacity (NFRC) from the PRC calculated for several recent days in which reserves were relatively tight. –Dark blue line shows the aggregate telemetered NFRC. –Green line is the new PRC based on the new calculation. –Red line is the old PRC –Blue bars at the bottom show the difference between new PRC and old PRC –The orange dotted lines show the online ORDC adder on these days. For the purpose of discussion only4/3/2015

28. 28 1/8/2015 Morning Peak HE8 @ 57,489MW For the purpose of discussion only4/3/2015

29. 29 1/13/15 Morning Peak HE8 @ 49,854MW For the purpose of discussion only4/3/2015

30. 30 1/16/2015 Morning Peak HE8 @ 50,011MW For the purpose of discussion only4/3/2015

31. 31 12/27/2014 Entire Day For the purpose of discussion only4/3/2015

32. 32 1/8/2015 Entire Day For the purpose of discussion only4/3/2015

33. 33 8/25/2014 Peak HE17 @ 66,427MW For the purpose of discussion only4/3/2015 This is a hypothetical scenario for 8/25/14 (summer peak) using NFRC data from 1/8/15 (winter peak as of 1/16/15) to adjust the PRC. NFRC was not in telemetry until 11/1/14.

34. 34 Proposed EEA Changes 4/3/2015For the purpose of discussion only

35. 35 Recap of EEA discussion 2 example EEA events –Frequency responsive capacity available, but low reserves (Aug 3 2011) –Sufficient reserves, but low Frequency responsive capacity (Jan 18 2014) Requirement from BAL-003 could lead to future changes. Under EEA 3, ERCOT may have to maintain frequency at 59.91 Hz (BAAL requirement) instead of current 59.80 Hz PRC should reflect frequency responsive capacity but the current implementation includes capacity that is not frequency responsive 4/3/2015For the purpose of discussion only

36. 36 Current EEA 3 Trigger and Objective Current EEA 3 Trigger –When all other resources and demand side resources will not allow for steady state frequency to be maintained at 59.8 Hz or greater ERCOT may enter EEA-3. –ERCOT shall enter EEA-3 if steady state frequency falls below 59.5 Hz. –No trigger based on remaining PRC. Current EEA 3 Objective –ERCOT directs all TSPs and DSPs or their agents to shed firm Load, in 100 MW blocks, in order to maintain a steady state system frequency of 59.8 Hz. –No objectives concerning amount of PRC that should be restored when determining the amount of load shed, only frequency. EEA 3 : Firm load interruption imminent or in progress 4/3/2015For the purpose of discussion only

37. 37 Proposed EEA 3 Trigger and Objective Proposed EEA 3 Trigger –PRC (frequency responsive) sustained below 1000 MW; or –System frequency sustained below 59.8 Hz (may change to 59.91 Hz upon approval of BAL-001-2) Proposed EEA 3 Objective –Maintain frequency responsive PRC so that Most Severe Single Contingency (MSSC) will not cause 1 st Stage UFLS to trip. –Do not allow system frequency below 59.8/59.91 Hz greater than 30 min. contingent upon BAL-001-2 standard getting approved –ERCOT will continue to shed firm Load, in 100 MW blocks in order to maintain a steady state system frequency of 59.8/59.91 Hz or greater. –30 minute out Resource status and Demand outlook is typically considered in addition to current conditions in determining the magnitude of firm Load Shed. EEA 3 : Firm load interruption imminent or in progress 4/3/2015For the purpose of discussion only

38. 38 SC4: Frequency Response, Net Load = 35 GW Net Load = 35 GW, Generation Trip 1350 MW 1---: PFR = 1400 2---: PFR = 900 3---: PFR = 600 with UFLS 4/3/2015For the purpose of discussion only

39. 39 SC4: Frequency Response, Load = 67 GW Load = 67 GW, 500 MW Load Ramp + One STP Trip 1---: PFR = 1250 2---: PFR = 900 3---: PFR = 600 4---: PFR = 300 with UFLS 5---: PFR = 100 with UFLS 1,000 MW is a conservative PFR to account for winter peak (~58 GW) and or lower than studied frequency starting point. 4/3/2015For the purpose of discussion only

40. 40 Current EEA 2 Trigger and Objective Current EEA 2 Trigger –Maintain system frequency at 60 Hz, or –Maintain a total of 1,750 MW of PRC. Current EEA 2 Objective –Utilize Load management procedures to maintain system frequency at 60 Hz, or –Utilize Load management procedures to maintain a total of 1,750 MW of PRC. –Load management procedures utilize the following: Responsive Reserve Service (RRS) Load Resources (LR) Any un-deployed Emergency Response Service (ERS) Distribution Level Voltage Reduction Public Appeals for load reduction Block Load Transfers (BLT) –Load reduction by the load management procedures minimize or avoid the use of firm load shed if EEA 3 is needed. EEA 2 : Load management procedures in effect 4/3/2015For the purpose of discussion only

41. 41 Proposed EEA 2 Trigger and Objective Proposed EEA 2 Trigger –System frequency sustained below 60 Hz but greater than 59.91 Hz, or –Sustained PRC below 1750 MW but above 1000 MW Proposed EEA 2 Objective –May not enter EEA 1 due to a system disturbance which temporarily reduces PRC to below 2,300 MW Utilize Load management procedures to maintain system frequency at 60 Hz, or –Utilize Load management procedures to maintain a total of 1750 MW of PRC –Utilize same Load management procedures as Current. EEA 2 : Load management procedures in effect 4/3/2015For the purpose of discussion only

42. 42 Current EEA 1 Trigger and Objective Current EEA 1 Trigger –Maintain a total of 2,300 MW PRC Current EEA 1 Objective –Maintain sufficient PRC for the loss of two large units (1150 each) –Utilize all available Generation Resources and DC Tie capacity that can respond in time for the EEA. –Utilize 30 minute ERS –EEA 1 may be declared even if due to a system disturbance which temporarily reduces PRC to below 2,300 MW EEA 1 : All available resources in use. 4/3/2015For the purpose of discussion only

43. 43 Proposed EEA 1 Trigger and Objective Proposed EEA 1 Trigger –PRC sustained below 2,300 MW * Proposed EEA 1 Objective –Maintain current level of PRC 2300 MW of PRC should be sufficient to avoid 1 st Stage UFLS for the largest category C (N-2) event(RCC) during expected scarcity conditions (high load). –Utilize all available Generation Resources and DC Tie capacity that can respond in time for the EEA. –Utilize 30 minute ERS EEA 1 : All available resources in use. *May not enter EEA 1 due to a system disturbance which temporarily reduces PRC to below 2,300 MW unless PRC is not expected to be restored to above 2,300 MW within 30 minutes (allows NSRS and QSGRs to potentially restore PRC) 4/3/2015For the purpose of discussion only

44. 44 Please send us your feedback at ssharma@ercot.com by April 17 th, 2015 ssharma@ercot.com 4/3/2015For the purpose of discussion only