NPRR351 Look-Ahead SCED Update

Hailong Hui/Sai Moorty ERCOT METF November 27, 2012

Outlines

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RTD Issue of Identifying Competitive Constraints RTD VS SCED Ramping Constraint Impact to First Interval BP RTD VS SCED Summary for Study Period 10/22/2012-11/18/2012

– GTBD and System Lambda Mean Absolute Error (MAE) – Load Zones LMP MAE – GTBD Error for Interval 6 – System Lambda Error for Interval 6

RTD VS SCED Price Spikes Analysis for Interval 6

– OD 10/30/2012 Price Spikes – OD 11/17/2012 Price Spikes November 27, 2012 2 METF

RTD Issue of Identifying Competitive Constraints

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This issue was brought up in the 10/26/2012 METF meeting

– there were noticable price differences between RTD first interval and SCED at 09/24/2012 IE 22:30 and 22:35. Normally the RTD first interval solution should be the same as SCED if there is no EMS telemetry difference.

ERCOT has investigated this issue and found out

– In certain scenarios, RTD failed to identify the competitive constraints, i.e. some of the competitive constraints will be treated as non competitive and will not be enforced in Step1 for any of the 11 intervals. It caused different solution between RTD first interval and SCED.

The fix for this issue has been released and scheduled to be migrated into production in Dec. 2012.

Two Examples and plots for this issue:

– 09/24/2012 IE 22:30 and 22:35 – 11/02/2012 IE 06:55 and 07:00 November 27, 2012 3 METF

RTD Issue of Identifying Competitive Constraints- 09/24/2012

November 27, 2012 4 METF

RTD Issue of Identifying Competitive Constraints- 11/02/2012

November 27, 2012 5 METF

RTD VS SCED Ramping Constraint Impact to First Interval BP

• • •

The Study Period is 06/28/2012-11/14/2012 The Logic used for the Ramping Constraint Impact Study:

– For each online resource, compare RTD first interval base point from multi interval optimization against SCED base point and calculate the positive error as MAX(0, RTD BP-SCED BP) – Calculate the system total positive BP error by summing up the positive error for all the online resources above for each 5-minute interval of the study period.

– Calculate the average of the system total positive BP error for each 5-minute interval ending between IE 00:05-24:00 by averaging the system total positive BP error for all the intervals with the same 5-minute interval ending within the study period.

The study results shows that the big average error always happens at IE HH:00 (RTD and SCED run at (HH-1):55).

– This is due to the current RTD shutdown profiling logic. The errors are much bigger at IE 22:00, 23:00 and 24:00 because more units are shut down at end of the day compared to other time. The implemented RTD shutdown profiling shuts resources down faster than what actually happens.

November 27, 2012 6 METF

RTD VS SCED Ramping Constraint Impact to First Interval BP

November 27, 2012 7 METF

RTD VS SCED Summary: GTBD and System Lambda MAE

November 27, 2012 8 METF

RTD VS SCED Summary: Load Zones LMP MAE

November 27, 2012 9 METF

RTD VS SCED Summary: GTBD Error (Interval 6)

November 27, 2012 10 METF

RTD VS SCED Summary: System Lambda Error (Interval 6)

November 27, 2012 11 METF

RTD VS SCED GTBD and System lambda for OD 30OCT2012

November 27, 2012 12 METF

SCED GTBD and System Lambda for OD 30OCT2012

November 27, 2012 13 METF

RTD VS SCED GTBD and System lambda for OD 17NOV2012

November 27, 2012 14 METF

SCED GTBD and System Lambda for OD 17NOV2012

November 27, 2012 15 METF