Compensation of Harmonics in Neutral Current Using Active Power Filter for Three Phase Four Wire System

Abstract

Increased penetration of nonlinear loads like power electronic converter based systems haveaggravated issue of harmonic injection in the power system. Neutral current harmonics is anissue of concern for three phase four wire system. This paper is focused on the elimination ofneutral current harmonics with the help of shunt active power filter based on the star-deltatransformer and single phase half bridge inverter. The presented active power filter eliminatesharmonics present in neutral current which in turn helps in mitigating third harmonics from thesupply mains. The topology has the advantage of reduced number of semiconducting devicesand switching losses as compared to conventional three phase active filter. Simulation studiesfor the proposed active filter are presented and compared with the behavior of conventionalthree phase active filter. Experimental results for DSP based laboratory prototype of theproposed filter are shown to substantiate performance of system. Both simulations, as well asexperimental results, demonstrate effective compensation provided by single phase half bridgeinverter based active filter.