A %THD analysis of industrial power distribution systems with active power filter-case studies

Abstract

Increasing use of variable speed drives in industry causes harmonic proliferation in industrial power distribution supply system. Harmonic currents generated by the variable speed drives interact with power system impedance to give rise to harmonic voltage distortion. Thus it is essential to analyze, evaluate and introduce appropriate mitigation techniques for harmonic reduction in the power system networks. In this paper, %THD harmonic load flow analysis for different industrial power system networks in the presence of harmonic loads has been carried out using DIgSILENT software. From the %THD harmonic profile of different feeders and buses of the power distribution system, it is observed that there is more %THD present at certain feeders and buses where nonlinear loads are connected. In order to reduce the %THD within the allowable limits as per IEEE standards, both passive and active filters are designed and installed in the power system networks. Simulation results are presented to validate the proposed scheme. From the results, it is observed that the reduction of %THD is more in power system networks at various buses and feeders with active power filter compared to passive filter.