Grid Voltage Synchronization for Distributed Generation Systems under Grid Fault Conditions

Abstract

Grid synchronization algorithms are of great importance in the control of grid-connected power converters, as fast and accurate detection of the grid voltage parameters is crucial in order to implement stable control strategies under generic grid conditions. This paper presents a new grid synchronization method for three-phase three-wire networks, namely three-phase enhanced PLL The enhanced phase-locked loop (EPLL) is a synchronization system that has proven to provide good results in single phase synchronization systems. An EPLL is essentially an adaptive band pass filter, which is able to adjust the cutoff frequency as a function of the input signal. Its structure was later adapted for the three-phase case, in order to detect the positive-sequence vector of three-phase signals, This paper analyses the performance of the proposed synchronization method including different design issues. Moreover, the behavior of the method for synchronizing with highly unbalanced grid is proven by means of simulation demonstrating its excellent performance.