Synchronization strategy of microgrid from islanded to grid-connected mode seamless transfer

Microgrid should be operated in both grid-connected and islanded mode to ensure high voltage quality and reliability. In the case of continuous uninterrupted power supply, seamless transfer is important between the two modes,and synchronization of the voltage of the point of common coupling (PCC) and utility grid should be finished first to achieve the goal. In this paper varies of synchronization strategies used in different microgrid control structures from islanded mode to grid-connected mode are summarized, and a new method based on droop control is proposed. This method does not affect power sharing during synchronization procedure. Simulation and experiment results are presented to show the feasibility of the method.