A Seamless Transfer Strategy Based on Multi-master and Multi-slave Microgrid

In this paper, a combined method of direct current control and droop control method for multi-master and multi-slave architecture is proposed to improve the reliability of microgrid in islanding mode. Upon the occurrence of utility outage, the master distributed generation (DG) units can realize seamless transition from a current source control to a voltage source control independent of islanding detection, and the quality of load transient voltage is not affected during transferring process. The existing seamless transfer control strategies are mostly based on single-master and multi-slave microgrid structure. In this paper, multiple parallel master DGs can prevent system fault in case of the only master DG fails and improve the reliability in islanding mode. The simulation results are provided to verify the effectiveness of this proposed control method.