Computational Implementation and Comparative Analysis of Phase-Locked Loop (PLL) Methods Under Different Power Quality Disturbances

This paper addresses the computational implementation and the comparative analysis of three Phase-Locked Loop (PLL) methods: Classic, TD-PLL (QSG group) and SOGI-PLL (AF group). These methods are used in Distributed Generation (DG), composing Microgrids and Smart Grids, for synchronization and monitoring. They are extremely important for integrating these systems into the power grid and, therefore, they must comply with standards such as IEEE 1547 and ABNT NBR 16149. These standards impose frequency and voltage variation limits in order to connect the DG systems to the low-voltage power system. For verifying the correct operation of the PLLs under different grid conditions, computational results about the performance of each one are presented. Both ideal and highly distorted grids are considered to analyze the behavior of each PLL method under variations of frequency, phase angle and voltage amplitude. The evaluation criteria are: frequency oscillation, settling time and phase error in steady state.