Research on Self-adaptive Dual-mode Operation Control Strategy for Micro-grid Based on Virtual Synchronous Generator

The virtual synchronous generator (VSG) control strategy is widely used in distributed power supplies for the stable operation. In order to meet the needs of grid-connected and island dual-mode operation, a self-adaptive dual-mode operation control strategy based on VSG is proposed in this paper. Firstly, the dual-mode operation control strategy of VSG is given, that is, the current-controlled VSG is adopted in grid-connected mode and the voltage-controlled VSG is adopted in island mode. In order to realize seamless switching, a new slow start control strategy is proposed in switching from grid-connected mode to island mode. Then, to solve the overload problem caused by VSG control in grid-connected operation, a current-controlled VSG with self-adaptive droop-damping coefficient and reactive power droop coefficient is proposed. Finally, the proposed control strategy is verified effectively by simulation on the energy-stored quasi-Z-source inverter micro-grid system.