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John Dumas Director Wholesale Market Operations ERCOT

Real-Time Dispatch (RTD) Basic Building Block Of “Look Ahead SCED” Proposed Scope For Summer 2012 & Examples. John Dumas Director Wholesale Market Operations ERCOT. Why “Look-Ahead SCED” ?.

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John Dumas Director Wholesale Market Operations ERCOT

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  1. Real-Time Dispatch (RTD)Basic Building Block Of “Look Ahead SCED”Proposed Scope For Summer 2012&Examples John Dumas Director Wholesale Market Operations ERCOT

  2. Why “Look-Ahead SCED” ? The goal of “Look-Ahead SCED” in its final version is to eliminate the following limitations of the current single interval SCED: Cannot serve load during steep load ramps due to Generation Resource ramp rate limitations. Does not efficiently commit and dispatch QSGRs. Cannot handle Load Resources with Minimum Deploy Time and Energy Storage Resources with limited energy. Does not consider future topology changes e.g. Outages. Does not accommodate Real-Time Co-Optimization of Energy and Ancillary Services. Does not provide non-binding short term forward prices. “Commitment” of Load Resources having temporal constraints (similar to QSGRs)

  3. Main Components of “Look-Ahead SCED” • The main components of “Look Ahead SCED” are: • Real-Time Commitment (RTC) Application • Real-Time Dispatch (RTD) Application • The Real-Time Commitment (RTC) Application executes every 15 minutes with arolling window for up to two hours study period that is comprised of up to 7 time intervals of 15 minutes each. The outputs of RTC are: • Commitment Instructions for Generation, Load and Energy Storage Resources. • AS Awards and MCPC. • The Real-Time Dispatch (RTD) Application executes every 5 minutes with a rolling one hour window study period that is comprised of 12 time intervals of 5 minutes each. The outputs of RTD are: • Dispatch Instructions (Energy MW Base points) for Generation, Load and Energy Storage Resources. • LMP at all Settlement Points and Electrical Buses.

  4. Moving Forward on “Look Ahead SCED” : Proposed Approach • Key Points: • Significant change to the Real-Time Market • Requires rigorous involvement of Market Participants and IMM.

  5. Moving Forward on “Look Ahead SCED” : Proposed Approach • Proposed Approach: (“Agile” Delivery) • Phased implementation. • Develop requirements / draft protocols for a given phase. • Components of “Look Ahead SCED” will be rolled into production in STUDY mode. i.e. outputs are NOT binding. • Similar to open-loop LFC testing prior to nodal go-live. • Utilize actual production data to verify/analyze non-binding results. • Present & review results to stakeholders for each implemented phase • Modify design/implementation as necessary after each phase implemented. • Finalize & Approve Protocols.

  6. Moving Forward on “Look Ahead SCED” : Proposed Approach • Phase 1 “Look-Ahead SCED” • The first component of “Look-Ahead SCED” to be phased in will be a basic version of the Real-Time Dispatch (RTD) application • RTD key feature is a simultaneous multi-interval optimization with explicit ramp rate constraints modeled. • RTD is the dispatch engine in Real-Time Commitment (RTC) application. • NPRR 351

  7. Proposed Scope Of Real-Time Dispatch (RTD)Summer 2012 • Current Production SCED will continue to provide the settlement Base Points and LMP for dispatch and pricing. • Real-Time Dispatch (RTD) in STUDY mode: • Real-Time Dispatch (RTD) will run in parallel in study mode to current Production SCED. • ALL LMPs and Base Points from RTD are NOT BINDING. i.e. they are advisory. • Real-Time Dispatch (RTD) inputs will utilize the SAME inputs as the current Production SCED and additionally will utilize other inputs (short term load forecast, WGRPP). • Forward LMPs at Settlement Points (NPRR351) will be output from Real-Time Dispatch (RTD) and posted on MIS Public, as well as QSE Resource  Base Points on MIS Certified reports (neither data set will be telemetered).  • By running in parallel Market will be able to observe production “what-if” for this building block of “Look-Ahead SCED” (similar to open-loop LFC testing prior to nodal go-live)

  8. Proposed Scope Of Real-Time Dispatch (RTD)Summer 2012 • Real-Time Dispatch (RTD) in STUDY mode: (continued) • Key feature of Real-Time Dispatch (RTD) will be the multi-interval optimization ( 1 hour study horizon comprising of twelve (12)  5-minute intervals) incorporating explicit ramp-rate constraint modeling. • Differences between MW dispatch and LMP for a given SCED interval between current Production SCED and Real-Time Dispatch (RTD) may occur if ramp constraints are binding due to future conditions.

  9. Proposed Scope Of Real-Time Dispatch (RTD)Summer 2012 ICCP & MIS Binding MW Dispatch & Binding Prices for SCED interval T Current Production SCED Current SCED Inputs Advisory MW Dispatch & Advisory Prices (LMP only) for SCED interval T+5, …T+60 Real-Time Dispatch (RTD) Additional “Look Ahead” Inputs MIS

  10. Comparison of Current SCED And Real-Time Dispatch (RTD) Concepts

  11. Comparison of Current SCED And Real-Time Dispatch (RTD)Ramp Constraints: LMP, Base Point, Offer Price Relationship

  12. Examples Current SCED & Real-Time Dispatch (RTD)

  13. Example 1: No Ramping Constraints – Load Peak • Resource Parameters • Price Curves $/MWh $/MWh 40 30 20 10 MW MW 5 5 0 0 15 15 Unit 2 Unit 1

  14. Example 1: No Ramping Constraints – Load Peak (continued) • Current SCED (sequential) System Dispatch • “Look-Ahead SCED” - RTD System Dispatch Total Cost 1140 Total Cost 1140

  15. Example 1: No Ramping Constraints – Load Peak (continued) • Current SCED (sequential) • Unit 1 Dispatch • Unit 2 Dispatch Total Profit 450 Total Profit 50

  16. Example 1: No Ramping Constraints – Load Peak (continued) • “Look-Ahead SCED” - RTD • Unit 1 Dispatch • Unit 2 Dispatch Total Profit 450 Total Profit 50

  17. Example 2: Ramping Constraints – Load Peak • Resource Parameters • Price Curves $/MWh $/MWh 40 30 20 10 MW MW 5 5 0 0 15 15 Unit 2 Unit 1

  18. Example 2: Ramping Constraints – Load Peak (continued) • Current SCED (sequential) System Dispatch • “Look-Ahead SCED” - RTD System Dispatch Total Cost 1560 Total Cost 1180

  19. Example 2: Ramping Constraints – Load Peak (continued) • Current SCED (sequential) @T+5, the load to be served is 27MW, the system is 2 MW short. The System Lambda is set by the under generation penalty cost of 250$/MWh. • Unit 1 Dispatch • Unit 2 Dispatch Total Profit 3600 Total Profit 2150

  20. Example 2: Ramping Constraints – Load Peak (continued) • “Look-Ahead SCED” - RTD • Unit 1 Dispatch • Unit 2 Dispatch Total Profit 600 Total Profit 130

  21. Example 2: Ramping Constraints – Load Peak (continued) • “Look-Ahead SCED” – RTD • @T+0, the system lamda is set by Unit 1 = 20$/MWh. Unit 2 cost is 30$/MWh and the price is 20$/MWh. LMP < offer price for Unit 2 but unit 2 is ramped UP. • @T+5, System Lambda is the change in objective function to a change in demand (by +-1 MW). If system demand changes by +1 MW for T+5, then change in objective function is: +40 $ for Unit 2 moving up 1 MW for T+5 +30 $ for Unit 2 moving up 1 MW for T -20$ for Unit 1 moving down 1 MW for T =50$ • @T+10, Unit 1 is marginal. Unit 2 is ramp constrained (DOWN). This is similar to what happens with CURRENT SCED when resource dispatched down to LDL. Here, Unit 2 LMP ($20) < Offer Price ($30) and is dispatched DOWN.

  22. Example 3: Ramping Constraints – Load Valley • Resource Parameters • Price Curves $/MWh $/MWh 40 30 20 10 MW MW 5 5 0 0 15 15 Unit 2 Unit 1

  23. Example 3: Ramping Constraints – Load Valley (continued) • Current SCED (sequential) System Dispatch • “Look-Ahead SCED” - RTD System Dispatch Total Cost 1050 Total Cost 590

  24. Example 3: Ramping Constraints – Load Valley (continued) • Current SCED (sequential) @T+5, the load to be served is 9MW, the system is 2 MW over. The System Lambda is set by the over generation penalty cost of 250$/MWh. • Unit 1 Dispatch • Unit 2 Dispatch Total Profit -2280 Total Profit 0

  25. Example 3: Ramping Constraints – Load Valley (continued) • “Look-Ahead SCED” - RTD • Unit 1 Dispatch • Unit 2 Dispatch Total Profit 320 Total Profit 0

  26. Example 3: Ramping Constraints – Load Valley (continued) • “Look-Ahead SCED” – RTD • @T+0, The System Lambda is set by Unit 2 is 30$/MWh. Unit 1 cost is 20$/MWh and the price is 30$/MWh. LMP > offer price for Unit 1 but Unit 1 is ramped DOWN. • @T+5, System Lambda is the change in objective function to a change in demand (by +-1 MW). If system demand changes by +1 MW for T+5, then change in objective function is: +20 $ for Unit 1 moving up 1 MW for T+5 +20 $ for Unit 1 moving up 1 MW for T -30$ for Unit 2 moving down 1 MW for T =10$ • @T+10, Unit 2 is marginal. Unit 1 is ramp constrained (UP). This is similar to what happens with CURRENT SCED when resource dispatched up to HDL. Here, Unit 1 LMP ($30) > Offer Price ($20) and is dispatched UP.

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