A Critical Review of Harmonics and Mitigation Techniques in Power Systems

Abstract

The application of nonlinear loads in electrical power systems has increased significantly in recent years. These include variable speed drives (VSDs), uninterruptible power supplies (UPS), industrial rectifiers, welding machines, fluorescent lighting systems (Electronic ballast), computers, electronic appliances and other equipment with switched mode power supplies (SMPS) all of which have nonlinear voltage-current characteristics and produce harmonic distortions on the power system. Power system reliability and normal operation of electrical equipment depend heavily upon a harmonic free power supply. Harmonics have several adverse effects on the power system including overheating of wires, circuit breakers, transformers, and other equipment, the nuisance tripping of breakers and saturation of various magnetic components. This study is a critical review of power system harmonics, its causes, effects, and the mitigation techniques for harmonic voltages and currents. The paper suggests that power systems engineers carry out regular evaluation and harmonic distortion analysis of electrical facilities especially industrial plant facilities while planning facility construction or expansion whereas vendors of variable frequency drives (VFDs) and such non-linear loads should help recommend equipment capable of reducing system harmonics in compliance with the IEEE 519 and similar regulatory guidelines. The work will be useful to Field Engineers and System Designers as it provides useful information for efficient and effective mitigation of harmonics in both modern industrial and non-industrial power system facilities.

Keywords: Harmonics, power systems, power system reliability, waveform distortion