Fuzzy-Based Reactive Power and Voltage Control in a Distribution System

This paper presents fuzzy-based reactive power and voltage control in a distribution system. The main purpose is to find the combination of main transformer load tap changer (LTC) positions and capacitor on/off switching operations in a day, such that the voltage deviations at the secondary bus of main transformer become as small as possible, while the reactive power flows through the main transformer and the real power losses at feeders become as little as possible. To minimize system repair cost, the total number of switching operations of LTC and capacitors in a day must be kept as few as possible. The linguistic expressions such as "as small as possible," "as little as possible," and "as few possible" are not close. In this paper, the reactive power and voltage control problem is first formulated with fuzzy sets, and then an annealing search technique is used to find a proper combination of LTC positions and capacitors on/off switching operations in a day. To demonstrate the effectiveness of the proposed method, reactive power and voltage control in a distribution system within the service arm of Yumlin District Office of Taiwan Power Company (TPC) is analyzed. It is found that a proper dispatching schedule for LTC positions and capacitors switching operations can be reached by the proposed method.