Neural network based control of reduced rating DSTATCOM

Abstract

This paper presents a DSTATCOM controlled by a neural network based reference current extractor (NNREC) and rating reduction by use of shunt connected capacitor bank for three-phase three-wire system. The working of DSTATCOM with self supported dc bus is used in two different modes; one is, unity power factor (UPF) mode and second is, zero voltage regulation (ZVR) mode. The heart of the control of DSTATCOM is the derivation of reference currents, which decide the switching of three legs of voltage source inverter (VSI) used in DSTATCOM. The NNRCE is used for control of DSTATCOM, which operates on LMS algorithm. The real positive sequence current component of current is extracted using NNRCE without any phase shift. A PI controller is used to regulate the voltage across the capacitor connected at the dc bus of the VSI. In the ac voltage regulation mode, second PI controller is used to maintain the constant voltage at PCC with variation of load. To reduce the rating of DSTATCOM, an ac capacitor bank of almost half rating of the VAR required is connected at the load end. The simulations are carried out in MATLAB environment for unity power factor operation and ac voltage regulation through leading power factor operation. Simulation results verify the effectiveness of the DSTATCOM system to meet the requirements of distribution system.