微网运行模式平滑切换的控制策略研究

摘要

To meet the requirements of both islanded and grid-connected operation of microgrid and to realize the smooth transition between the two modes, a reference adjusting control loop is added to the basic droop controller. By switching the loop. PQ control and droop control are implemented in grid-connected and island mode respectively. A pre-synchronizing controller is designed to synchronize the inverter to the grid when the islanded microgrid needs to reconnect to the grid. This control unit effectively restrains the impact current in the parallel connection. A mode transition process is proposed and validated by simulation. The microgrid simulation experiment also verifies several other operational conditions both in islanded mode and grid-connected mode.This work is supported by National Natural Science Foundation of China (No. 50910234).%针对微网孤岛与并网运行模式的特点,提出了一种实现微网运行模式平滑切换的控制策略,即在基本下垂控制器中增加下垂额定点调节环,通过该环路的投切实现并网与孤岛控制模式的平滑转换,微电源并网为PQ控制,孤岛为下垂控制.设计了逆变器预同步控制单元,有效地抑制微电源并联过程的冲击电流,使并网过程平稳安全.在此基础上,提出一种微网运行模式相互切换的控制流程,并对微网运行模式切换以及孤岛和并网状态下的若干运行工况进行了仿真实验,验证了控制方法与切换流程的有效性.