Probabilistic Operation of Electric Power Systems Considering Environmental Constraint (Part 6)* -An Improvement of The Convenient Method-

A method for economic load dispatch is expected to satisfy many constraints. The constraints, in this paper, are the supply demand balance, the emission constraint and the line capacities. A convenient method and a strict method have already been reported in the previous memoir. The purpose of this report is to present some improvements on the previously reported convenient method, in terms of no estimating error, application to many transmission capacity constraints and rapid estimation. These improvements make use of the Kuhn-Tucker conditions. It is shown that the number of non-zero LaGrange multipliers must be not more than the number of thermal generating units when the constraints can be satisfied. In the proposed method, a proper combination of non-zero multipliers is sought. The selection of the multipliers for non-zero is done by the partial differential coefficients. The proposed method and the strict method are applied to a model system. From many simulation results, it is shown that the proposed method can rapidly estimate the optimum load dispatch without error even if many line capacities are constrained