GTBD Forecasting Using SCED to Produce Projections of Future LMPs Floyd J. Trefny February 17, 2011

Topics ERCOT System Load Examples  Sunday, January 30, 2011  Thursday, February 3, 2011 GTBD Forecasting Methodology Analysis of Forecasting Errors Implementation in SCED Next Steps

Average Mw Change in Mw/Min over 15-minute SCED interval

GTBD Forecasting Methodology GTBD (Generation To Be Dispatched) is the sum of the Base Points dispatched in SCED Typically, calculated by summing up the current actual generation from all the Generation Resources that are going to be dispatched by SCED SCED LMPs are based on this amount of total power A reasonable forecast of future GTBD can be calculated from:  System ramp rate sampled over the last fifteen minutes Ramp rate may be positive or negative  Add: Real-Time SCED GTBD + (Ramp Rate*15) gives the “Forecasted GTBD”

Implementation in SCED In addition to the existing SCED, execute the same SCED algorithm once at the top of each 15-Minute period, but using the Forecasted GTBD Use same offer curves, Resource Limits and Status that were available to SCED for the actual dispatch of generation Assume that the same transmission constraints that are active in real time SCED are also active in the Forecast SCED calculation Provide via ICCP and post on MIS, the LPM’s generated for:  Resource Nodes  Hubs  Load Zones (LMPZ)

Next Steps Get Comments from ERCOT Staff Draft NPRR WMS Discussion Seek expedited implementation to support Quick Start objectives and demand response

Discussion

Appendix

SCED UP and SCED Down