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Application of Active Filters in Power Systems

Authors: Onah AJ, Ezema EE, Uzodife NA

DOI Info:


This paper is intended to show how current harmonics are generated by some nonlinear loads, and how these harmonics can be suppressed. Majority of loads such as induction motors, battery chargers, static converters, light fittings, arc furnaces, transformers, cables, and transmission lines draw both sinusoidal currents and currents which are multiples of the supply frequency, commonly called harmonics. These harmonics pollute the AC mains resulting in poor quality power supply, which is detrimental to many sensitive loads. This paper shows how an active filter (AF) can be used to filter the harmonics in the supply current so as to produce near-sinusoidal current. The paper describes the operation of both the non-linear load and the active filter. The performance equations are derived, and the characteristics obtained. The phase-controlled rectifier is a major cause of harmonic pollution in the AC system network. As an example of nonlinear load, the three-phase, full-wave controlled rectifier was examined. The principle of operation of the rectifier was described, the input equations derived, and the distorted input current characteristic shown. Application of the active filter (AF) to minimize these harmonics follows. The application of active filter results in sinusoidal currents, and consequently reduction in total harmonic distortion (THD) and improvement in system power factor.

Affiliations: Department of Electrical/Electronic Engineering, College of Engineering and Engineering Technology, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria.
Keywords: Non-linear Loads, Current Harmonics, Reactive Power, Power Factor, Active Filter
Published date: 2021/06/30

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ISSN: 2635-3342 (Print)

ISSN: 2635-3350 (Online)

DOI: In progress

ISI Impact Factor: In progress

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