A Robust-Synchronization-Loop for Grid-Connected Distributed Generation Converters

In this paper, a novel Robust-Synchronization-Loop (RSL) is proposed to track the phase and frequency of the grid voltage. The method can be widely applied to the grid-connected converters in integration of distributed generations (DGs). The detailed analytical model and the parameter tuning based on a small-signal model of the RSL are presented. It is shown that the eigenvalues associated with the RSL remain always on the left half-plane, thus, it provides better stability property with the grid-connected DG converters. In order to show the effectiveness of the proposed RSL, simulation results are provided for different scenarios of the grid conditions. The results show that the proposed method effectively tracks the phase and frequency of the grid voltage and maintains the good synchronism of the DG converters during these different small and large disturbances in the power system.