An Improved Control Method for Multiple Bidirectional Power Converters in Hybrid AC/DC Microgrid

In this paper, an improved control method for multiple bidirectional power converters is proposed to reduce the circulating current and power-sharing deviation among converters when the hybrid ac/dc microgrid operated in island mode, which can enhance the security of parallel converters. First, a unified detection method for circulating current and power-sharing deviation is described. Then, the improved control method for bidirectional converters in hybrid microgrid operated in island mode is presented to reduce circulating current and power-sharing deviation, which includes the droop controller used to achieve automatic power sharing and the improved virtual impedance controller used to further reduce circulating current and power-sharing deviation. At last, simulation and experiment results verified that the proposed control method can simultaneously achieve circulating current reduction and automatic power sharing, and does not decrease the output power capability of converter. The proposed control method is suitable for the configuration that has a specific bus between bidirectional power converters, and the ac bus connected to ac loads and the host grid.