Analysis of Main Topologies of Shunt Active Power Filters Applied to Four-Wire Systems

This paper presents a complete comparative study about the five most common configurations of shunt active power filter applied to four-wire distribution systems. In order to evaluate the applicability of the studied topologies, two scenarios of four-wire loads are investigated differing by level of zero-sequence harmonic contents. The analysis of simulation steady-state results comprise dc-link capacitor voltage and current stresses, harmonic distortion in grid currents, and semiconductor losses. The results show that structures with fourth inductor generate higher number of levels at output converter voltage. However, when they operate by compensating high levels of zero-sequence harmonics, they can present higher dc-link voltage and lower efficiency. Furthermore, system models, control strategy, and experimental results are presented as well.