Decentralised power sharing control strategy in LV microgrids under unbalanced load conditions

In this paper, a decentralized control strategy for inverter-based distributed generation (DG) is proposed to enhance the accuracy of power sharing under unbalanced load conditions in low-voltage microgrids. The proposed method includes two important saliences: (1) accurate unbalanced current injection from DGs, and (2) reduction of circulating real and reactive powers in an islanded microgrid. The features are complied with the proposed droop strategy utilized in the control system of each phase of DG converters. Based on the proposed triple-droop control strategy, the real power sharing in an AC low-voltage microgrid is significantly improved via P-V control strategy and the reactive power sharing accuracy is enhanced via Q-f control strategy. By this method, the amplitude of the output voltage of each phase of the converters is determined based on the amount of load connected to that phase. In addition, the efficiency of the microgrid is increased due to the circulating current reduction between DGs. A virtual impedance concept is also utilized to improve the accuracy of the proposed power sharing method. The feasibility and effectiveness of the proposed strategy are validated using MATLAB/SIMULINK software for International Council for Large Electric Systems (CIGRE) low-voltage distribution network benchmark.