2014

10-Year
Assessment

Load forecasting methodology

ATC will initially use load forecasts provided by the company’s end-use load-serving customers. Such customers are required, under ATC’s Distribution-Transmission Interconnection Agreements and Network Operating Agreements, to provide ATC with monthly peak demand forecasts for the next ten years. ATC may, in the future, develop load forecasts either concurrent with or independent of the company’s load-serving customers. In addition, ATC may, in coordination with the company’s load-serving customers, develop representative load duration curves based on actual and normalized load conditions. The ATC methodology for developing, aggregating and maintaining load forecast information will follow the NERC Standards MOD-010-0 and MOD-011-0.

In utilizing or developing load forecasts, the following methodology will be used:

  1. Summer peak demand forecasts will be calculated in such a way that there is an almost equal probability of exceeding or falling short of the forecast when average peak making weather does occur.
  2. Shoulder peak demand forecasts will be developed such that the scalable loads are scaled to a pre-calculated percent of the summer peak demand forecasts while holding the non-scalable loads smaller than or equal to 5 MW constant and applying shoulder load ratios for the non-scalable loads greater than 5 MW. The resultant overall ATC load in the Shoulder peak model is ~70 percent of the summer peak. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.
  3. Winter peak demand forecasts will be developed such that the scalable loads are scaled to Local Distribution Company (LDC) chosen percentages for the month of January.  Non-scalable loads remain unchanged. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.
  4. Fall/spring off-peak demand forecasts will be developed such that the scalable loads are scaled to LDC chosen percentages for the month of November for fall or the month of April for spring. Non-scalable loads smaller than or equal to 5 MW remain unchanged while applying shoulder load ratios for the non-scalable loads greater than 5 MW. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.
  5. Summer 90/10 proxy peak demand forecasts will be developed that reflect above-average summer weather and peak demand conditions. A true summer 90/10 forecast will be calculated in such a way that there is a 90 percent probability of falling short of and a 10 percent probability of exceeding the forecast due to weather conditions. Until ATC develops the capability for producing a specific 90/10 forecast, we will assume that it can be reasonably approximated through increasing the summer peak conforming load forecast by about 5 percent and leaving the non-scalable loads unchanged. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.
  6. Light load (50 percent of summer peak) demand forecasts will be developed such that the conforming loads are scaled to a pre-calculated percent of the summer peak demand forecasts while holding the non-scalable loads smaller than or equal to 5 MW constant and applying light load ratios for the non-scalable loads greater than 5 MW. The resultant overall ATC load in the Light load model is ~50% of the summer peak. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.
  7. Minimum load (40 percent of summer peak) demand forecasts will be developed such that the conforming loads are scaled to a pre-calculated percent of the summer peak demand forecasts, while holding the non-scalable loads smaller than or equal to 5 MW constant and applying light load ratios for the non-scalable loads greater than 5 MW. The resultant overall ATC load in the Minimum load model is ~40% of the summer peak. The ratio of the real to reactive power of the loads will remain unchanged from the summer peak ratio.