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Ramp Rate for Congestion Management and Delivering Ancillary Services

Ramp Rate for Congestion Management and Delivering Ancillary Services

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Ramp Rate for Congestion Management and Delivering Ancillary Services

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  1. Ramp Rate for Congestion Management and Delivering Ancillary Services Resmi Surendran

  2. Observations Issue • Too much AS capacity reserved in single Resource Effect • Resources needed for congestion management doesn’t have Ramp Rate available for SCED to re-dispatch since it is reserved for Regulation • Room available for SCED is limited to HASL and hence capacity is unavailable for congestion management • Reserved AS capacity are not simultaneously deliverable due to ramp limitation and not converted to energy when deployed hence affecting reliability

  3. Ramp for Congestion Management SURAMP = RAMPRATE – (RUSTELEM/ 5) SDRAMP = NORMRAMP – (RDSTELEM / 5) Where SURAMP/SDRAMP - SCED up/down ramp rate RAMPRATE- Normal Ramp Rate when RRS is not deployed or when the subject Resource is not providing RRS. Emergency Ramp Rate for Resources deploying RRS RUSTELEM/ RUSTELEM -Reg-Up/Down Ancillary Service Resource Responsibility designation provided by telemetry

  4. Need Protocol Change • With minimal system change • That ensures that at least some capacity is available to SCED from all Resources to resolve congestion. • That reduces the time needed to resolve congestion there by increase the efficiency and reliability of congestion management

  5. Suggested Protocol Change SURAMP = RAMPRATE – (RUSTELEM* REGP / 5) SDRAMP = NORMRAMP – (RDSTELEM * REGP / 5) Where SURAMP/SDRAMP - SCED up/down ramp rate RAMPRATE- Normal Ramp Rate when RRS is not deployed or when the subject Resource is not providing RRS. Emergency Ramp Rate for Resources deploying RRS RUSTELEM/ RUSTELEM -Reg-Up/Down Ancillary Service Resource Responsibility designation provided by telemetry REGP- Percentage of Regulation Service for which Ramp Rate will be reserved in Real-Time. The value will be between one and zero.

  6. Possible Effects of the Protocol Change • This change may result in a Resource being asked to move more quickly than the Resource can ramp, however this should not be a regular occurrence • Regulation and Base Points for the Resource would have to both being moving significantly in the same direction • Per ERCOT’s comments for NPRR 277, a QSE may have intervals during which this occurs removed from the monthly resource energy deployment performance calculation • These intervals may already have been exempted, i.e. if there was large unit trip causing a frequency deviation

  7. Possible Effects of the Protocol Change • How often could this happen? • During October ‘10, 10 minute changes in the regulation deployment exceeded 75% of the regulation service requirement less than 1% of the time • For positive changes, the regulation up requirement was used • For negative changes, the regulation down requirement was used

  8. AS Deliverability Requirement The protocols require that the QSE providing Ancillary Service in Real-Time shall ensure that the Resource carrying the Ancillary Service capacity has enough Ramp Rate to provide the reserved Regulation Service energy in five minutes, Responsive Reserve Service energy in ten minutes and Non-Spin Reserve Service energy in 30 minutes when the services are deployed.

  9. AS Deliverability Requirement • DAM doesn’t consider Ramp Rate when awarding AS • Except checking RRS award<= 10* max ERR • It is QSEs responsibility • to bid into AS only the amount that can be delivered in RT • to schedule in RT in a Resource only the amount of AS that can be deployed simultaneously

  10. Option 1 – Both REG & RRS in 10 min • REG UP offer <= NRR * 5 • RRS offer <= Min (.2 * HSL , NRR * 10 – REG UP offer) • NSRS offer <= NRR * 30 - REG offer – RRS offer • REG DN offer <= NRR * 5 Ramp Rate >= Max of • REG UP/5 • (RRS+ REG UP)/10 • (NSRS+RRS+REG UP)/30

  11. Option 1 – Both REG & RRS in 10 min If ERR not equal to NRR then • REG UP offer <= NRR*5 • RRS offer <= Min(0.2 *HSL , ERR*10 – REG UP offer ) • NSRS offer <= min (NRR*20 + ERR*10 – REG UP – RRS, NRR*30) • REG DN offer <= NRR*5 Ramp Rate >= max [REG/5, (RRS+ REG UP)/10, (NSRS)/30, (NSRS+RRS+REG UP- ERR*10)/20]

  12. Option 2 – No Simultaneous Delivery • REG offer <= NRR * 5 • RRS offer <= ERR * 10 • NSRS offer <= NRR * 30 Ramp Rate >= Max of • REG/5 • RRS/10 • NSRS/30

  13. Option 3 – Reserving Ramp Rate for Regulation • REG offer <= NRR*5 • RRS offer <= Min [.2 * HSL , (ERR – REG UP offer/5)*10 ] • NSRS offer <= (NRR – REG UP offer/5)*20 Ramp Rate >= Max of • REG/5 • RRS/10 + REG UP/5 • NSRS/20 + REG UP/5

  14. Expectations Between Nodal and Zonal for Option 1 • In Zonal, ERCOT has the same expectations for the deliverability of AS Zonal Example • Reg. Up = 1000, RRS from Gen. = 1150, and NSRS = 1500 • Ramp Rate >= max (1000/10, (1000+1150)/10, (1000+1150+1500)/30) = max(100, 215, 121.7) = 215 MW/Min Nodal Example • Reg. Up = 500, RRS from Gen. = 1150, and NSRS = 1500 • Ramp Rate >= max (500/5, (500+1150)/10, (500+1150+1500)/30) = max(100, 165, 105) = 165 MW/Min • This implies that less ramp rate will be required for AS in Nodal than it currently required under Zonal

  15. RRS Energy Deployment form Generators • From ONRR Resources • From SCED • if GTBD is increased from current generation by offset or load growth & ramp is available • Re-dispatching uneconomical regulation deployment if ramp is available • Converting regulation to BP if regulation is deployed on marginal units

  16. NSRS Energy Deployment form Generators • From Resources on Output Schedule • From SCED • if GTBD is increased from current generation by offset or load growth & ramp is available • Re-dispatching uneconomical regulation deployment if ramp is available • Converting regulation to BP if regulation is deployed on marginal units

  17. AS Offer Example • Assume: • A Resource with an HSL = 600 MW and an LSL = 100 MW and Normal Ramp Rate = 10 MW/min = Emergency Ramp Rate. • The Resource can supply no more than the Min(0.2*600, 100) = 100 MW of RRS. • The Resource offers and is struck during an hour in the DAM for 100 MW of RRS and 50 MW of Regulation Up Service. • All 100 MW of RRS is deployed

  18. AS Offer Example • Then • The SCED Up Ramp = 10 MW/min – 50/5 Mw/Min = 0. • In this case, the SCED High Dispatch Limit = Net Power Output; SCED issues a Base Point = Net power Output; the Resource will not follow the RRS capacity deployment with an energy deployment only by converting the Regulation deployment to Base Point. • If a big unit tripped which requires more regulation than in procured then both RRS need to be deployed at the same time. Since the Ramp Rate of the Resource is 10 MW/min the maximum energy that can be delivered in 10 min is 100 even if both REG & RRS are deployed • The responsibility for assuring that the AS Offer is deliverable belongs with the QSE. If the QSE offers both RRS and Reg-Up into the DAM, the QSE should no offer more than 100 MW of REG & RRS combined.

  19. AS Offer Example The QSE could manage the ramp limitation for the AS Offers by the following method if the QSE can deliver REG & RRS in first 10 min and NSRS in the last 20 min. • REG offer <= NRR * 5 • RRS offer <= NRR * 10 – REG UP offer • NSRS offer <= NRR * 30 – REG UP offer – RRS offer

  20. Ramp Rate for AS • QSEs should offer in DAM or self schedule AS amounts based upon a ramp rate that can be achieved across/over at least 70% of the operating range. • Operating range is defined as HSL-LSL. • QSEs should select the ramp rate range in which the Resource will be loaded the majority of the operating time.

  21. Ramp Rate Example

  22. Appendix

  23. AS Offers • AS Offers requirements are contained in Nodal Protocol 4.4.5. • The Business Rules for AS Offer Submissions are included in the following documentation: • MMS- Day-Ahead Market and Supplemental Ancillary Service Market Requirements Specification (B2) version 4.0, Appendix 5. http://nodal.ercot.com/docs/pd/mms/pd/damsasmr/mms_dam_and_sasm_req_09q1_v4_0%20%28blackline%29.doc • MMS – Explanation of Market Submissions Items version 0.3 http://nodal.ercot.com/docs/pd/mms/odfr/emsi/mms_explanation_of_market_submission_items_v0_30.doc • EIP - External Interfaces Specification version 1.19P http://nodal.ercot.com/readiness/sandbox/docs/eip_external_interfaces_specification_v1_19P.zip • Market Manager User Guide Version 0.06 http://nodal.ercot.com/readiness/markettrials/connectivity/keydocs/Market_Manager_User_Guide_06.doc

  24. AS Offers Cleared in the DAM • The DAM solution co-optimizes AS Offers and Three Part Supply Offers for a Resource across the DAM’s Operating Day study period. • This results in the maximization of a Resource’s earnings across the Operating Day relative to its Energy and AS Offers that are cleared in the DAM. • The DAM clearing engine enforces the following Resource limits: • The total Energy and AS capacity for the Regulation Up/Down, Non-Spin and Responsive Reserve awarded to the Resource must be less than or equal to the Resource’s HSL. • The amount of Off-line Non-spin AS capacity awarded to the Resource must be less than or equal to the Resource’s HSL – LSL. • Responsive Reserve Service awarded to a Resource must meet the requirements established by Nodal Protocol 3.18: • The amount of RRS provided from a Generation Resource must be less than or equal to 20% of thermal unit HSL for an Ancillary Service Offer and must be less than or equal to ten times the Emergency Ramp Rate (the DAM uses the maximum emergency ramp rate as submitted in the RARF or Market Manager Resource Parameter Update Application); • Hydro-powered Resources operating in the synchronous condenser fast-response mode may provide RRS up to the Resource’s proved 20-second response (which may be 100% of the HSL); • For any hydro-powered Resource with a five percent droop setting operating as a generator, the amount of RRS provided may never be more than 20% of the HSL; and • The amount of RRS provided from a Load Resource must be less than or equal to the HSL minus the LSL. • The DAM clearing engine does not consider Resource Ramp Rates in the optimization of Energy or AS Offers. • The DAM Offer validation process checks that the offering Resource is qualified to provided the offered AS but does not check if the offered quantity is within the Resource’s qualified amount.

  25. AS Offer Business Rules • AS Offers must be submitted according to the following groups: • Regulation Down • Online reserves, including Regulation UP, responsive Reserve and Online Non-spin • Offline Non-spin • Each AS Offer Group is treated independently • Within each group AS Offers that are submitted are studied as hourly offers, subject to the following: • AS Offers in each hour may consist of up to 5 blocks of AS offers. In each hour, the DAM may clear AS Offers from multiple blocks. • Each block of AS Offers may be designated as a fixed or variable block • Fixed means that the AS Quantities specified in the block may only be struck only if the entire quantity for an AS Service in the block is dispatched. This can only be used by Load Resources and cannot exceed 150 MW. • Variable means that the AS Quantity dispatched for an AS Service specified in the block may be up to the quantity specified in the offer. • Contiguous hours may be grouped together by use of the multi-block designator – if the multi-block indicator is set the AS Offer will only be struck if all hours in the block are cleared. • A Resource submitting a Three Part Supply Offer and AS Offers in the same hour may designate the Energy Offer as Inclusive meaning that the Resource can only be selected by the optimization if the Energy Offer and /or AS Offer is cleared in that hour. If only AS offer is cleared then at least LSL energy will be awarded • A Resource submitting a Three Part Supply Offer and AS Offers in the same hour may designate the Energy Offer as Exclusive meaning that the Resource can be cleared by the optimization to provide either Energy only or Ancillary Services but not both in the same hour. • If Exclusive AS Offers are dispatched in an hour, the DAM clearing engine simultaneously dispatches the Resource at its LSL.

  26. Characteristics of AS Services • Regulation Service (Reg-Up and Reg-Down) • Regulation Service is the amount of energy that a Resource is qualified by ERCOT to deliver in 5 minutes. • The amount of a Resource’s regulation energy deployment is determined by the QSE assigned Regulation Participation Factor applied to the QSE’s Regulation Energy deployment directed by ERCOT’s LFC system. • A portion of the Resource’s Ramp Rate equal to the Regulation AS Resource Responsibility ÷ 5 minutes is reserved for Regulation energy deployment from economic deployments (i.e. the SCED Up Ramp = (Normal Ramp Rate – Reg Responsibility/5), where the SCED Up Ramp is the ramp rate used to determine the economic deployment limits for SCED.

  27. Characteristics of AS Services • Responsive Reserve Service (RRS) • RRS is the amount of energy that a Resource is qualified by ERCOT to deliver in 10 minutes. • RRS capacity is deployed by the QSE upon an instruction from ERCOT to release Responsive Reserve Capacity for SCED Energy Dispatch. • SCED based on the Resource’s Energy Offer Curve controls the amount of energy deployed by the Resource. • For Resources supplying RRS capacity deployed by ERCOT, the SCED uses the a SCED Up/Down Ramp Rate determined by using the Resource’s emergency ramp rate at the current Net Power output to determine the maximum and minimum energy deployment instruction that can be issued to the Resource (refer to Slide 4).

  28. Characteristics of AS Services • Online Non-spin Reserve Service (NSRS) • NSRS is the amount of energy that a Resource is qualified by ERCOT to deliver in 30 minutes. • NSRS capacity is deployed by the QSE upon an instruction from ERCOT to release Non-Spin Reserve Capacity for SCED Energy Dispatch. • SCED based on the Resource’s Energy Offer Curve controls the amount of energy deployed by the Resource. • For Resources supplying NSRS capacity deployed by ERCOT, the SCED uses SCED Up/Down Ramp Rate determined by using the Resource’s Normal Ramp Rate at the current Net Power output to determine the maximum energy deployment instruction that can be issued to the Resource (refer to Slide 4).