Simplified Design of Passive Power Filters of Series Hybrid Active Power Filters

Abstract

Series hybrid active power filter (SHAPF) attracts much attention of electrical engineers and researchers because of its better filtering characteristics, lower initial and running costs and reduced resonance possibility. Recently, the most typical SHAPF can be categorized into four types in terms of their operation principle: a) combined system of shunt passive and series active power filters, b) series active power filter based on a sinusoidal current-controlled voltage-source inverter, c) SHAPF based on the fundamental magnetic flux compensation (FMFC) of a series transformer, and, d) novel SHAPF. The characteristics of these four series active power filters were summarized, especially their harmonic equivalent impedances were compared. The harmonic equivalent impedances in the SHAPF based on FMFC of a series transformer and novel SHAPF were so high that the passive power filter design criterions were quite different from that of conventional passive power filter, and the passive power filters can be simplified. Three simplified passive power filters were proposed and their applications were given. These simplified passive power filters can greatly decrease cost and complexity of system design. Validity of these three kinds of simplified passive power filters is verified with experimental results with two kinds of typical harmonic sources.