Control strategy of energy storage system in muti-modes of microgrid

According to different operating modes of microgrid, different control strategies for energy storage system are presented. When microgrid parallels in the grid, the bus voltage of microgrid was supported by grid, and the energy storage system serves as the PQ source, using PQ control strategy; When microgrid is off-grid, the energy storage system serves as the main power supply of microgrid, using VF control strategy. In order to remain stable operation of the system under imbalance grid voltage or load, a controller was designed in the positive and negative sequence rotating coordinate, and the control system was of double loop control structure. In this paper, energy storage system models were built in PSCAD in order to analyze the running mode of energy storage systems both in on-grid /off-grid mode, which confirmed the feasibility and effectiveness of the control strategy used in this paper.