DFT-based controller for sag and harmonic mitigation with a series-connected compensator

Abstract

Voltage-quality problems in power distribution networks include harmonics, voltage sags and swells and unbalances. These problems may seriously affect sensitive industrial loads causing production interruption or equipment damage. Now-a-days series voltage compensation using power electronics devices is a promising solution for these problems and the design, control and application of this type of devices have drawn much attention in the literature. In fact, comprehensive controllers for power electronics series compensator have already been proposed in the literature to tackle all those problems simultaneously. For example, repetitive controllers show very promising performance although several aspects still need closer attention. This paper proposes a different type of controller based on a Discrete Fourier Transform to minimise voltage harmonic pollution using power electronics series devices. The design process of this type of controller is straightforward regardless of the number of harmonics to be tackled. In addition, the proposed controller uses a slow sampling rate and its computational effort is relatively low. The main contributions of this paper are illustrated by simulation.