Research on Seamless Transfer Strategy of Micro-grid Based on Energy Storage

Energy storage plays a vital role in the reliable operation of Micro-Grid (MG) due to its characteristic of running stabilization and control flexibility. It can act as the master inverter and maintain system voltage and frequency stability as MG in off-grid mode under voltage control mode. During the transfer of MG from grid-connected mode to off-grid mode, the PCC (point of common coupling) three-phase static switch can't shut off at the same time. Moreover it needs to match the MG voltage and utility grid voltage when the islanded MG needs to reconnect to the utility grid. In order to solve these problems, a control strategy of grid-connected/off-grid seamless transfer based on energy storage is proposed. Simulation was presented from a MG platform including photovoltaic (PV), wind turbine (WT) and energy storage and the results show the feasibility of the proposed approach.