Short Term and Mid Term Load Forecast

1. Short Term and Mid Term Load Forecast John Dumas Supervisor, Operations Planning ERCOT January 24, 2007

2. ERCOT Load Forecasts • ERCOT uses three primary types of load forecast. • Long Term • Mid Term • Short Term • This presentation will cover only short term and mid term load forecast.

3. Short Term Load Forecast • Period covered: • Every 5 minute period for the next hour. • The STLF program runs every 5 minutes. • Used for: • Determining Balancing Energy deployments 25 minutes prior to the start of the interval. • Developed by AREVA

4. STLF Error

5. Mid Term Load Forecast • Period covered: • Each hour period for the next 7 days. • The MTLF program runs every hour. • Used for: • Day Ahead reliability studies. • Decisions on Unit Commitment • OOMC • Replacement Reserve • Developed by: • AREVA • PRT

6. MTLF Error

7. Causes of MTLF Error • Error in Weather Forecast • Temperature • Humidity • Wind Chill • No good way to account for probability of rain • Load Response • May be based on energy cost (MCP) or 4CP anticipation • ERCOT has limited knowledge of this behavior

8. January 15, 2007 MTLF Day Ahead 16:00 MAPE: 5.84

9. January 15, 2007

10. January 15, 2007

11. January 15, 2007

12. January 16, 2007 MTLF Day Ahead 16:00 MAPE: 6.0

13. January 16, 2007

14. January 16, 2007

15. January 16, 2007

16. January 17, 2007 MTLF Day Ahead 16:00 MAPE: 2.63

17. January 17, 2007

18. January 17, 2007

19. January 17, 2007