A Novel Method to Control Volt/Var in the Grids via Fuzzy Controller

This paper presents two new strategies to control Volt/Var in the grid. A nonlinear fuzzy controller regulates the modulation index of voltage source converter (VSC), used in an uninterrupted power supply (UPS) application. Other method implements two dc sources to control input of VSCs, hence controlling Volt/Var. The proposed systems regulate the voltage at the point of common coupling (PCC) even during changing dc source voltage condition or unbalanced load. With the aid of an LC filter connected at the output of the VSC, switching harmonics are removed. Based on PCC voltage error, fuzzy controller determines the value of modulation index of VSC. In comparison with a conventional PI controller, effectiveness of our controllers is studied by wide range of operating condition such as harmonics, unbalancing and voltage sag/swell. Simulation results depict the effectiveness of performance of proposed methods