LOAD MANAGEMENT: IMPACTS ON ELECTRIC UTILITY PLANNING AND OPERATIONS.

Load management describes any action taken by an electric utility to modify its loads. Load management concepts useful to U. S. utilities are defined, the European economic justifications for load management are analyzed, and the near-term benefits possible by managing loads are determined. Evaluations of load management are complex, but preliminary calculations demonstrate significant short-term benefits. Comprehensive economic analyses are necessary to avoid possible long-term problems, including those experienced in Europe. Customer load management strategies can be classified as either demand or energy management: Demand management is modification of the power demand pattern to reduce daily peak loads; Energy management is modification of energy consumption patterns to achieve conservation of energy and scarce fuel resources, or to increase energy sales during off-peak periods. For the purpose of this paper, the term load management is used to denote customer load management. Case studies were performed on two U. S. utilities: a primarily coal-fired, winter-peaking northern system and a primarily oil-fired, summer-peaking southern system. Both utilities also operate nuclear power plants and both burn substantial amounts of natural gas. The impacts of load management on the two utilities were different, reflecting the differences in characteristics of their individual load patterns and generation mix. For the oil-fired utility, energy management (conservation) was found to be more effective than demand management (peak shaving to shift demand from peak to off-peak periods). In contrast, the operating costs for the coal-fired utility showed much greater response to demand management than to energy management. This occurred because oil-fired generation provided peaking energy, and peak loads could be shifted to coal-fired units with much lower operating costs, which were not fully loaded during off-peak periods.