A method of three-phase balancing in microgrid by photovoltaic generation systems

Recently, a small-scale power system has been able to perform autonomous or islanding operation with some distributed generators. But in such a microgrid, it is afraid that serious voltage imbalance may be caused by unbalanced loads during the islanding operation. Fortunately, grid interactive inverters of the distributed generators often have some amount of surplus capacity. This paper deals with a three-phase balancing method utilizing the surplus capacity. By the proposed method, the inverters output negative sequence currents to suppress the voltage imbalance within their surplus capacities. Operating characteristics and its effectiveness are confirmed by some simulation results.