Effects of direct load control on power system reliability and production cost

It is no longer advantageous for electric utilities to encourage and serve uncontrolled load growth. Thus, the concept of Load Management has become important and is increasingly practiced in various forms as an alternative to or in conjunction with system capacity additions to satisfy load requirements. Accordingly, a need exists for accurate and efficient methods which incorporate Load Management to assess and evaluate the effects of load control in context with system supply-side variables. Direct load control is a form of Load Management in which portions of the system load are under the direct operational control of the utility. Thus, the load can be modified, within limits, to match the available generating capacity thereby minimizing events of uncontrolled load loss. In this research, it is shown that system reliability improvements and operating cost reductions afforded by exogenous models of direct load control are different from those given by dynamic models of direct load control. To this end, this research report describes the dynamics of direct load control and an equal incremental cost scheme coupled with a Monte Carlo simulation model of the operation of thermal based electric utilities. Various system reliability indices and production measures produced by exogenous and dynamic models of direct load control are computed, compared and discussed. It is shown that accurate modeling of direct load control can not be made using exogenous load models, but requires models which recognize the dynamics of operation and the temporal correlation of load and available generating capacity.