Minimisation of VA loading of UPQC in three-phase four-wire distribution system

Unified power quality conditioner (UPQC) is a combination of series and shunt active power filters with a common DC link. This device is used to enhance power quality by injecting required amount of Volt-Ampere (VA) into the system. In view of the cost effectiveness, it is desirable to have VA loading of UPQC without compromising the compensation capability. This paper presents a methodology to minimise VA loading of UPQC, considering the effects of unbalance in load and distortions in both load current and source voltage during the compensation of voltage sag with phase jumps in adistribution system. The minimum VA loading of the UPQC is achieved by injecting a series voltage at an optimum angle using series active power filter with respect to the voltage sag. In this paper, a particle swarm optimization (PSO)-based technique is used to minimise the VA loading of UPQC. The proposed method has been validated through detailed simulation studies and the results are presented Copyright © 2012 Inderscience Enterprises Ltd.