Phase locked loop techniques for power quality improvement in polluted grids

Abstract

This paper presents the various phase locked loop (PLL) techniques for power quality improvement in polluted grids by phase angle and fundamental signal tracking. Multi-functional grid-tied inverters are paying much attention to handle power quality issues like reactive current and harmonic current compensation along with grid synchronization of various distributed generation units (DG's) and micro-grids. PLL's are playing a major role in order to improve the overall performance of the system. The power quality imrpovement can be effectively done with the tracking of phase angle, frequency and amplitude of the voltage or current signal of the utility grid. PLL techniques like SRF, Inverse Park, EPLL, SOGI with PI and SOGI with PR controllers are discussed and their performance is compared using MATLAB/Simuink. Various tests during abnormal grid conditions like frequency deviations, voltage sag and phase jump are conducted.