Advanced Phase-Locked Loop Synchronization Techniques for Utility Interface Converters Under Highly Distorted Operating Conditions

Dual second order generalized integrator (DSOGI) and multi-variable filter (MVF) based phase-locked loop (PLL) are extensively used in utility grid applications. The DSOGI-PLL is robust under unbalanced and distorted utility voltages and has a good performance but, it loses its qualities when it operates in high distorted grid voltages. On the other hand, the MVF-PLL is robust and has very good performance in the presence of harmonic distortions but, it suffers from a lack of robustness under unbalanced voltages compared to the DSOGI-PLL. The aim of this paper is to evaluate the performance of combined PLL technique (MVF-DSOGI-PLL) for utility interface converters under highly distorted Operating conditions, the results are then evaluated and compared to MVF and DSOGI PLL techniques using software simulation. In this paper, the structures of the MVF-, DSOGI- and MVF-DSOGI-PLL are presented and studied with the extraction of settling time for each technique, and their performance is evaluated and compared by means of various calculations and simulation results under a severely distorted grid scenario.