Harmonics: Generation and Suppression in AC System Networks

Abstract

Majority of loads such as induction motors, battery chargers, static converters, light fittings, arc furnaces, transformers, cables, transmission lines and so on draw both sinusoidal currents and currents which are multiples of the supply frequency, commonly called harmonics. These harmonics are out of phase with the supply voltage. The sinusoidal currents generate active power (kW), which is transformed into mechanical power and heat. The harmonics, on the other hand, give rise to reactive power (kVar) which enables electrical machines like transformers and motors to operate by magnetizing their cores. However, reactive power flow in electrical networks has adverse effects depending on their magnitude and the nature of the supply network. How these harmonics are generated by nonlinear loads and the means by which they can be kept low are the focus of this paper.

Keywords: non-linear loads, harmonics, reactive power, power factor