Bringing Renewables to the Grid. John Dumas Director Wholesale Market Operations ERCOT

Transcription

1 Bringing Renewables to the Grid John Dumas Director Wholesale Market Operations ERCOT 2011 Summer Seminar August 2, 2011

2 Quick Overview of ERCOT The ERCOT Market covers ~85% of Texas overall power usage (~75% of the land area) Record peak demand of 65,776 MW (occurred on 8/23/10) Total installed wind capacity of 9,500 MW 36,124 MW of new wind capacity generation requests under review Record peak WGR net MW power output of 7,355 MW (occurred on 6/19/11) 2

3 Topics Wind Forecasting Utilized by Reliability Unit Commitment Reserve Planning Ancillary Service Methodology Incorporates Wind Uncertainty Real Time Wind Generation Dispatch in a Nodal Market Typical Operation Energy Offer Curves Predicting Large Wind Ramps 3

4 Wind-powered Generation Resource (WGR) Power Forecasting Provided by AWS Truepower Two forecasts are produced for each WGR The Wind Generation Resource Production Potential (WGRPP) is an 80% probability of exceedence forecast The Short-Term Wind Power Forecast (STWPF) is the most likely or 50% probability of exceedence forecast Each hour a new forecast is created for the next 48 hours Aggregate forecasts are also created and sent to ERCOT Aggregate Wind Power Forecasts: Red = STWPF, Green = WGRPP 4

5 Recent Observed Ramps in ERCOT Ramp down on June 27 th, 2011 Ramp of ~3500 MW in 2 hours 5

6 Recent Observed Ramps in ERCOT Ramp up on July 5 th, 2011 Ramp of ~3500 MW in 3 hours 6

7 Ancillary Service Determination Methodology Regulation Reserve (reserves deployed by AGC) Accounts for the expected increase in installed Wind Generation for the upcoming month Provision to increase regulation requirements if the last 30 day average CPS1 score falls below 100 Non-Spinning Reserve (30 minute reserves) Moved away from a flat 1375 MW procurement around peak load hours depending on temperature forecasts Considers Load Forecast Risk and Wind Forecast Risk 7

8 Security-Constrained Economic Dispatch (SCED) Operation Security Constrained Economic Dispatch (SCED) prioritizes dispatch of all generation Determines the Base Points for all generation units in the system including wind generation Assures the maximum use of wind generation delivered to the ERCOT Load centers Allows wind generation to compete on a even field with other types of generation Correctly determines the price to be paid to wind generation for their energy when there are shortages and when there are excess amounts Manages transmission congestion for ERCOT dispatch 8

9 SCED Dispatch Special Features for Wind Generation Nodal Market provides for wind generators to send their maximum generation capability (High Sustained Limit) to ERCOT for use in every SCED cycle (nominally 5 minutes) Normally set at the current amount of wind production SCED uses this High Sustainable Limit to restrict dispatches to amounts that the wind generator can produce given current wind conditions SCED determines if the wind generation can be set to the maximum or if a reduction is needed to manage the transmission system SCED produces a Base Point for each wind Resource Sent to the controlling Qualified Scheduling Entity 9

10 ERCOT Large Ramp Alert System (ELRAS) System awareness tool provided by AWS through a web interface Utilizes the same data that is being provided by ERCOT for the wind power forecasts Includes the following: An estimation of the probability of a defined ramp event (i.e., 1000 MW up ramp in a hour) beginning in a particular interval Information regarding the weather event which is most likely to cause the ramping event (i.e., a cold front) Additional attributes for each predicted ramp event including most likely start time, duration and maximum ramp rate Time variant graphics to provide additional situational awareness Looks from the current time to 6 hours into the future 10

11 ERCOT Large Ramp Alert System (ELRAS) Graphical Forecast Forecast at 4:00 for March 1 st,

12 ERCOT Large Ramp Alert System (ELRAS) Situation Overview Forecast at 4:00 for March 1 st, 2010 Plot Using Power Curve Power for Observed Output Due to Curtailment 12

13 Conclusions Multiple tools which cover different time frames have been key in providing Operators with the necessary level of system awareness These tools are designed to give Operators different types of information Incorporating historical wind power forecast error and WGR output behavior in the Ancillary Service requirements determination has been key in ensuring sufficient reserves 13

14 Together Shaping the Future of Electricity 14