A New Approach Based on Fuzzy Controller for Volt/Var Control in Distribution System

In this paper we concern about implementing nonlinear Fuzzy controller which regulates the modulation index of voltage source converter (VSC),which is used in an uninterrupted power supply (UPS) application, to control Volt/Var in the grid. The UPS controls the voltage at the point of common coupling (PCC). A LC filter is linked at the output of the VSC to eliminate switching harmonics. In the fuzzy controller the value of modulation index of VSC, is determined from a fuzzy rule-base defined on PCC voltage error(e=V0-V„f) of the point of common coupling. The proposed fuzzy controller is designed using simple control rule-base and the most natural membership functions. The comparative performances of the proposed fuzzy controller and the conventional PI controller, have been investigated through wide range of operating condition such as harmonics, unbalancing and voltage sag/swell. From the simulation studies it has been found out that the performance of the proposed fuzzy controller is better than that obtained by the conventional PI controller