一种可实现微网系统快速平滑并网的主动同步控制策略

To guarantee a smooth transition from islanded mode to grid-connected mode, synchronization is the first issue to be considered. In this paper, a phase locked loop (PLL)-based active synchronization control approach is presented, which is implemented in the secondary control level of the microgrid hierarchical control structure by actively controlling the microgrid voltage to track the main grid. In this way, it can reduce the voltage difference to get the microgrid back into grid in minimum transient state. With the cross product of voltage vectors employed as the phase detector, the microgrid voltage frequency and phase are enabled to track the main grid at the same time. In addition, instead of fast communication to transmit signals in the time domain, the proposed method only needs a low-bandwidth communication link, which is simple and easy to implement. Finally, hardware-in-the-loop simulation and experiment results show the feasibility of the approach proposed.