A redundant parallel control strategy of multiple PCS (power conversion system) for microgrid in islanded operation

For multiple PCS parallel operation in microgrid, since the output voltage of multiple PCS has differences in phase and amplitude, a big circulating current and the uneven distribution of power comes into being among PCS. the characteristics of circulating current and the uneven distribution of power are analyzed in detail when multiple PCS in direct parallel operation, and a peer-to-peer P / Q droop control strategy based on V / F is proposed for microgrid in islanded operation. In the strategy, all of the PCS share a coordinating controller to distribute power and sending synchronous signal, and a P/Q droop control strategy based on V/F for single PCS is adopted. The strategy can restrain circulating current effectively, and realize current-sharing control of multiple PCS. And it can ensure that each PCS has the same status, and realize the redundant parallel operation of multiple PCS. Both the simulation and experimental results show that the control strategy is correct and effective.