Common and fixed‐poles resonant harmonic filters

Abstract

AbstractDistribution voltage harmonics corrupt the effectiveness of resonant harmonic filters in reducing waveform distortion. The same is with load current harmonics of frequencies other than those to which the filter is tuned. Low impedance for the distribution voltage harmonics and resonances of the filter with the inductance of the distribution system are responsible for degrading filter effectiveness. A Iso, a change in the supply system structure or parameters may affect filter effectiveness. Filter effectiveness improves when the harmful resonances of the filter with the system inductance, i. e. the poles of the filter transmittance, are sufficiently far from harmonic frequencies. This paper presents a method of synthesis of resonant harmonic filters with the poles located at the designer's discretion. A line inductor with an inductance of the order of the equivalent inductance of the distribution system reduces the dependence of filter performance on changes in the distribution system parameters. Such a filter is referred to as a fixed‐poles resonant harmonic filter. Filters designed with the method described in this paper have higher effectiveness and their performance is more predictable as compared to filters designed traditionally, referred to as common filters.