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EEA Workshop 2 June 19, 2014

EEA Workshop 2 June 19, 2014. EEA Workshop 1 Recap Dan Woodfin. Review of Current EEA Practices Chad Thompson. EEA Steps. EEA procedure in the ERCOT Protocols defined by levels. 1. Maintain 2,300 MW of on-line reserves.

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EEA Workshop 2 June 19, 2014

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  1. EEA Workshop 2 June 19, 2014

  2. EEA Workshop 1 Recap Dan Woodfin

  3. Review of Current EEA Practices Chad Thompson

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

  5. EEA Levels and Triggers • EEA 1 • Request available Generation Resources come on-line through manual HRUC or Dispatch Instructions • Suspend any Resource testing • Obtain DC Tie Imports if available • If needed, deploy ERS-30 • June – September Only • Deploy weather sensitive ERS • Deploy available TO Load Management Programs

  6. EEA Levels and Triggers • EEA 2 • Instruct TSPs & DSPs or their agents to use voltage reduction measures, if available and beneficial • Deploy ERS-10 • Deploy RRS from Load Resources with high-set under-frequency relays

  7. EEA Levels and Triggers • EEA 3 • Direct TSPs & DSPs or their agents to shed firm load in 100 MW blocks to maintain 59.8 Hz as documented in the Operating Guides • 6.5.9.4 (8) indicates that ERCOT may immediately implement EEA 3 when steady-state frequency is 59.8 Hz, and shall implement EEA 3 when below 59.5 Hz • Will be discussed later

  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

  9. EEA 1 Comparison

  10. 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

  11. EEA 1 Comparison EEA 1 Declared EEA 1 Terminated

  12. 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

  13. 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

  14. Dynamic Simulation Fred Huang

  15. Outline • NERC Requirement • BAL-003-1 • BAL-001-2 • Dynamic Assessment • Responsive Reserve Service Study

  16. NERC BAL-003-1 • Effective Date: R1 (4/1/2016), R2-R4 (4/1/2015) • Interconnection Frequency Response Obligation (IFRO) • ERCOT: 413 MW/0.1 Hz, http://www.nerc.com/FilingsOrders/us/NERC%20Filings%20to%20FERC%20DL/FR%20Annual%20Report%2012-27-13%20Final.pdf • Resource Contingency Criteria (RCC) is the largest category C (N-2) event. • ERCOT: 2,750 MW • One of the needs is to prevent UFLS first step • From ERCOT’s perspective: • No firm Under Frequency Load Shed (UFLS) following RCC

  17. NERC BAL-001-2 • Adopted by the NERC Board of Trustees on August 15, 2013 • Requirement R2: Average of ACE does not exceed its Balancing Authority ACE Limit (BAAL) for more than 30 minutes • ERCOT Interconnection • Low Frequency Trigger Limit = 59.91 Hz • High Frequency Trigger Limit = 60.09 Hz

  18. 2013 Net Load (GW)

  19. Frequency Response Test • ERCOT performed a frequency response assessment for the selected system conditions for the Future Ancillary Service framework. *PRC: Physical Responsive Capability **Wind Penetration = Wind output / Load ***System Inertia (GW-second) = Sum of (Machine MVA * H) / 1,000

  20. Definition • Primary Frequency Response (PFR): • The immediate proportional increase or decrease in real power output provided by a Resource and the natural real power dampening response provided by Load in response to system frequency deviations. This response is in the direction that stabilizes frequency. • Fast Frequency Response (FFR): • A response from a resource that is automatically self-deployed and provides a full response within 30 cycles after frequency meets or drops below a preset threshold. • Two FFR subgroups: • FFR1: trigger frequency at 59.8 Hz • FFR2: trigger frequency at 59.7 Hz • PFR and FFR help to stabilize the frequency but do not recover the frequency back to nominal frequency.

  21. Key Assumptions and Criteria • Study Assumptions • Only PFR units provide governor response • Load damping is assumed as 2%/Hz • Two stages of FFR services at different frequency threshold • FFR1: 59.8 Hz, FFR2: 59.7 Hz • ERCOT Firm Under Frequency Load Shed Settings

  22. 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

  23. SC1: No PFR, No FFR, Only System Inertia 60.0 Hz Generation Trip: 2750 MW Case 1---: Net Load = 65 GW, SI = 372 Case 2---:Net Load = 35 GW, SI = 236 Case 3---:Net Load = 17 GW, SI = 174 59.4 Hz 54.8 Hz SI (GW-second): 1 > 2 > 3

  24. SC2: Minimum PFR Needs w/o FFR Generation Trip: 2750 MW Case 1---: Net Load = 65 GW, PFR=1,300MW Case 2---: Net Load = 35 GW, PFR=2,500MW Case 3---:Net Load = 17 GW, PFR=4,700MW 60.0 Hz 59.3 Hz PFR (MW): 3 > 2 > 1

  25. SC3: PFR/FFR at HWLL 60.1 Case 3: Load = 25 GW, Wind = 7.2 GW Disconnect two STPs Scenario 1---: PFR=1,400 MW, FFR(59.7Hz)=1,400MW Scenario 2---: PFR=2,650 MW, FFR(59.7Hz)=900MW Scenario 3---: PFR=4,700 MW, FFR(59.7Hz)=0MW 59.4 Case 3: 1 MW FFR ≈ 2.35 MW PFR

  26. 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

  27. 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

  28. 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

  29. SC4: Frequency Response, Load = 36 GW 1---: PFR = 1400 , ~59.93 Hz 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

  30. Note

  31. Responsive Reserve Study • ERCOT will perform a RRS study and the results will support the annual revision of “Methodologies for Determining Ancillary Service Requirements” • Identify the minimum needs for RRS to meet the NERC and ERCOT requirements • Identify the cap for LRs in RRS • Explore the potential for the followings, • Different needs based on system conditions. • Substitution ratio between Generation Resources and LRs in RRS

  32. Physical Responsive Capability Sandip Sharma

  33. Outline • Review the intent of Physical Responsive Capability (PRC) • Use of PRC as trigger for Energy Emergency Alert (EEA) • Review current PRC calculation • Current PRC calculation isn’t necessarily representative of available capacity that can “quickly respond to system disturbances” • Examples from April 29, 2013 and May 22nd, 2014 • Review possible PRC calculation changes • ERCOT recommendation for PRC change

  34. 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. • 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. • Hydro Resources operating under synchronous condenser fast response mode can contribute their full HSL*RDF towards PRC (full response within 20 seconds) • Non-Controllable Load Resources providing RRS is 100% counted towards PRC. (full response within 0.5 seconds)

  35. Example 1 –Response from Combustion Turbine At HSL of 150 MW, maximum PRC contribution is limited to 30 MW CT responded with roughly 40 MW for this event Prior to event the CT was generating at 94 MW

  36. Example 2 – Response from Gas Steam Unit HSL is 375; Prior to event this unit was generating at 49 MW The unit responded with roughly 59 MW for this event, PRC contribution would have been limited to 75 MW

  37. Example 3 – Coal Unit The unit responded with roughly 54 MW for this event, PRC contribution would have been limited to 83 MW HSL is 597 MW; Prior to event this unit was generating at 514 MW

  38. Example 4 – Hydro under Fast Response Mode The unit responded with 28.30 MW for this event, PRC contribution would have been limited to 28.3 MW HSL is 28 MW; Prior to event this unit was at 0 MW

  39. ERCOTmonitors PRC for determining OCN, Advisory, Watch and EEA

  40. ERCOT monitors PRC for declaring EEA

  41. Physical Responsive Capability (PRC) Currently the ERCOT-wide Physical Responsive Capability (PRC) calculated as follows:

  42. Physical Responsive Capability (PRC)

  43. Changes to PRC in near Future • Once NPRR-573 is implemented, Wind Generation Resources that are Primary Frequency Response capable and under curtailment, will be contributing to the PRC. Maximum contribution from WGRs will also be limited to 20% of their HSL. WGR

  44. Issues with PRC Calculation • It includes capacity that cannot respond quickly to the system disturbances in other words it includes Non-Frequency Responsive Capacity (NFRC) • For Non-Controllable Load Resources (NCLR) PRC only includes portion of NCLR MW, that is under RRS obligation not the MW that would be triggered by Under Frequency Relay (UFR) set at 59.70 Hz. • Accuracy of HSL • Since June 1st - Generation Resources telemetering ONTEST, STARTUP or SHUTDOWN Resources Status are now excluded from PRC calculation

  45. April 29, 2013 Unit Trip Event

  46. Example 1 – Non-Responsive PRC HSL = 1007 MW

  47. Example 2– Non-Responsive PRC HSL = 555 MW

  48. May 22, 2013 Unit Trip Event

  49. Example 1 – Non-Responsive PRC HSL = 1017 MW

  50. Example 2 – Non-Responsive PRC HSL = 590 MW

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