Analysis and Comparison of Phase Locked Loop Techniques for Grid Utility Applications

This paper presents an analysis and comparison of phase locked loop techniques used in grid utility applications to find the voltage vector angle generated from the supply voltages. The phase locked loop (PLL) has a wide range of applications as distributed generation (DG), flexible AC transmission systems (FACTS), static VAR compensators, cycloconverters, active power filters (APF´s) and others systems connected to the utility. The performance of these systems in grid connected applications is strongly influenced by the adopted PLL strategy. For this reason, the goal of the proposed paper is to present a comparison of different PLL-based techniques for utility applications to indicate the appropriate solution dedicated to a specific application. The criteria to compare the phase locked loops techniques is the performance under distorted and unbalanced supply voltages.