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Impact of Economic Downturn on Competitive ERCOT IDR Load. Methodology. Extracted the LSEGUFE cuts for the most recent settlement BUSIDRRQ for competitive load only Excluded initial settlements January 1, 2007 – December 31, 2008 Summed IDR cuts by Weather Zone
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Methodology • Extracted the LSEGUFE cuts for the most recent settlement • BUSIDRRQ for competitive load only • Excluded initial settlements • January 1, 2007 – December 31, 2008 • Summed IDR cuts by Weather Zone • Estimated models using 1-1-07 to 9-30-08, but excluding: • Hurricane Edouard • Coast – 8-3-08 to 8-9-08 • All other Weather Zones – 8-4-08 to 8-6-08 • Hurricane Ike • Coast – 9-9-08 to 9-30-08 • Generated model estimates at the Weather Zone level up through 12-31-08 • Compared actuals to estimates at the Weather Zone and Ercot IDR total load level for 10-15-08 to 12-31-08 • No economic impact observed for IDR load prior to 10-15-2008
Model Statistics for Daily Energy Estimates • IDR Total Load Level: • R-Square - .944 • MAPE – 2.17% • MAD – 5.25 GWH • IDR Coast Model: • R-Square - .855 • MAPE – 2.35% • MAD – 2.58 GWH • IDR NCent Model: • R-Square - .950 • MAPE – 1.85% • MAD – 1.44 GWH • Other Weather Zone composite Model: • R-Square - .391 • MAPE – 6.08 % • MAD – 3.70 GWH
Model Actual GWH Diff ERCOT Total IDR Daily Load January 1 – December 31, 2008 GWH • Significant Load Reduction in September due to Hurricane Ike • Some residual hurricane reduction in October followed by economic downturn impact through year-end
Model Actual GWH Diff ERCOT Coast IDR Daily Load January 1 – December 31, 2008 GWH • Significant Load Reduction in September due to Hurricane Ike • Some residual hurricane reduction in October followed by significant economic downturn impact through year-end
Model Actual GWH Diff ERCOT NCent IDR Daily Load January 1 – December 31, 2008 GWH • Modest economic downturn impact mid October through year-end
Model Actual GWH Diff ERCOT Other WZones IDR Daily Load January 1 – December 31, 2008 GWH • No apparent economic downturn impact through year-end
ERCOT IDR Load Differences Actual Load – Model Estimate • The major economic downturn impact has occurred in the Coast Weather Zone and appears to be trending to a more severe level • Coast IDR load reduction accounts for 79% of the ERCOT total reduction • NCent IDR load reduction is consistently negative but does not appear to be trending down • Other Weather Zone IDR load reduction is more difficult to assess because of modeling limitations but may be reacting more slowly to the economic downturn