This paper develops an efficient and practical approach for determining the feasible optimal solution of the economic dispatch problem when some of the on-line units have prohibited operating zones. When a unit has prohibited operating zones, its operating region will be broken into isolated sub-regions, which results in multiple decision spaces for the economic dispatch problem. For each of the decision spaces, it can be either feasible or infeasible with respect to the system demand. The feasible optimal solution for the dispatch problem can only reside in one of the feasible spaces, and can be found by performing the conventional lambda-delta iterative search based on the equal-incremental-cost criterion in each of the feasible spaces. However, for a system with a large number of decision spaces, such exhaustive search method would not be acceptable in real time operation due to high computational time requirement. in this paper, a novel approach is proposed. It defines a small and advantageous set of decision spaces, uses an efficient algorithm to determine the most advantageous space and then, utilizes the conventional lambda-delta iterative method to find the feasible optimal dispatch solution.
