A Review on Recent Advanced Three-Phase PLLs for Grid-Integrated Distributed Power Generation Systems Under Adverse Grid Conditions

Abstract

The forever increasing contribution of the distributed power generation systems (DPGS) integration into the electrical power grid has led to more concerns regarding the synchronization techniques. Continuous research has resulted in successful replacement of conventional PLL grid synchronization method with advanced ones for control and operation of grid frequency, amplitude, and phase of utility voltage for grid-integrated applications. The presence of grid inaccuracies like grid faults, direct current (DC) offsets, voltage imbalances, harmonics, frequency changes, phase jumps, and interharmonics in phase-locked loop (PLL) input grid voltage generates inaccurate controller response which appear in the estimated amplitude, frequency, and phase of PLL. This review paper presents an overview of accurate PLL methods based on the use of a mathematically canceling disturbances-based decoupling cell for synchronization. The latest PLLs which are studied and compared here are decoupled dual synchronous reference frame PLL (DDSRF PLL), multi-sequence harmonic decoupling cell PLL (MSHDC PLL), decoupling network in αβ reference frame PLL (DNαβ PLL), harmonic interharmonic DC offset PLL (HIHDO PLL), and less complex disturbance rejection PLL (LCDR PLL) for proper selection according to grid-tied DPGS application.