FUZZY DYNAMIC-PROGRAMMING APPROACH TO REACTIVE POWER VOLTAGE CONTROL IN A DISTRIBUTION SUBSTATION/

A fuzzy dynamic programming (FDP) approach is proposed for solving the reactive power/voltage control problem in a distribution substation. The main purpose is to improve the voltage profile on the secondary bu s and restrain the reactive power flow into a main transformer at the same time. To reach our objectives, the load tap changer (LTC) usually installed in a main transformer is employed to adjust the secondary v oltage and the capacitor connected to the secondary bus is employed to compensate the reactive power flow for the load demands. We first for ecast the real and reactive power demands of a main transformer and it s primary voltages for the nest day. With these forecasting data at ha nd, a fast LTC tap position estimation formula that takes the load mod els into account is derived to effectively reduce the computational bu rden for the proposed approach. Practical constraints on bus voltage l imits, maximum allowable number of switching operations in a day for t he LTC and capacitor and the tolerable worst power factor for a main t ransformer are also considered. To demonstrate the usefulness of the p roposed approach, reactive power/voltage control at a distribution sub station within the sen,ice area of Taipei City District Office of Taiw an Power Company is investigated. It is found that a proper dispatchin g schedule for the LTC and capacitor can be reached by the proposed ap proach.