A novel approach to the design of a shunt active filter for anunbalanced three-phase four-wire system under nonsinusoidal conditions

摘要

A new approach is presented for the design of a shunt activenfilter in a three-phase, four-wire distribution system with unbalanced,ndistorted sources and unbalanced loads. The purpose of the shunt activenfilter is to provide compensation currents such that the source needs tonsupply balanced (positive-sequence) fundamental source current at unitynpower factor even though the load consumes harmonic currents as well asnpositive, negative, and zero-sequence currents. A major feature of thenproposed approach is that it does not require symmetrical componentntransformation to transform the three-phase voltages and currents tonΑ-Β-o quantities. This makes practical implementation of thenproposed method easier than the symmetrical component transformationnapproach. In addition, the power factor of the positive-sequencenfundamental component is close to unity and only positive-sequence powernis supplied by the source. The effectiveness of the proposed controlnalgorithm is demonstrated by computer simulation and experimentalnresults of a shunt active filter for a three-phase four-wirendistribution system with distorted, unbalanced source voltages andnunbalanced loads