FUZZY OPTIMIZATION FOR ECONOMY-SECURITY COORDINATION IN POWER SYSTEM PLANNING

Abstract

In the power system expansion planning, the sum of the equipment construction cost (fixed cost) and operation cost (variable cost) is used as a major criterion to be minimized, but, on the other hand, the supply reliability must also be maintained at a desirable level. In the present paper, the power system expansion planning is formulated as a reliability-economy coordination problem. The loss of load probability (LOLP) is selected as the reliability index while the equipment operation cost and the new equipment construction cost are used for the economy index. And, the Fuzzy set theory, which is an effective approach to the optimization problem having such an ambiguity and trade-off relation is applied. Also, an attempt is made to obtain the solution coordinating the two indices by setting up functions, known as the membership functions, which express the ambiguity of the constraints and objectives. And, the possibility of system planning reflecting the intentions of the planner by variously changing the membership functions will be shown. This approach will be applied to a test system to clarify its practicability and the problem to be solved for implementing in real systems.