Implementation of passive and active filter for harmonic mitigation

Abstract

The utilization of non-linear loads has become a major concern especially in the industrial power system. The operation of the loads could draw harmonic currents and voltages which appear at the utility-consumer point of common coupling (PCC). In addition, if the harmonic occurs at the same frequency when the power system is at resonance, it could result in amplification of the harmonic distortion, or known as harmonic resonance. Three-phase Adjustable Speed Drives (ASDs) are a common source of harmonics. The variation of modulation index of a specific phase-width modulation (PWM) controller thus distributes harmonic frequencies within the main power lines. The overall harmonic components are further aggravated by the inclusion of DC link components for rectification process. The introduction of passive and active power filters (PPFs and APFs) thus reduces the overall harmonic current distortion occurring within the main power lines. Single-tuned passive filters provide fair harmonic isolation relative to its tuning frequency for harmonic resonance, although they introduce limitations on reactive power compensation. Shunt active filters cover greater range over harmonic compensation at wide harmonic frequencies. Shunt active filters provide greater performance in terms of power factor improvement compared to single-tuned passive filters.