基于电压电流协同控制的微网运行模式无缝切换策略

主从型微网从并网切换到孤岛时,主逆变器由电流控制模式切换到电压控制模式,需改变控制器结构,并且孤岛检测期间电压不可控。针对上述问题,提出一种电压电流协同控制策略,在整个运行过程中用电压控制器对微网内负载的电压进行控制。并网时电压控制器经调节后平衡微网内负载功率并达到稳定输出;同时附加上电流控制器控制输出电流,保持微网和电网间功率平衡。孤岛后电流控制器退出运行,电压控制器继续控制微网内负载电压,保证微网内负载功率始终处于平衡状态,控制器输出具有连续性,控制模式也平滑切换到电压控制。根据所述电压电流协同控制策略设计了相应的电压控制器和电流控制器。最后进行Simulink仿真及实验验证,结果证明了协同控制策略能实现微网运行模式的无缝切换。

Seamless Transfer Strategy of Operation Mode for Microgrid Based on Collaborative Control of Voltage and Current

When master-slave microgrid is transfered from grid-connected mode to islanding mode, the control mode of master inverter changes from current control to voltage control. But the controller structrue must be transferred and voltage is unable to be controlled in islanding detection period. To solve the above problems, a control strategy based on collaborative control of voltage and current is proposed, in which load voltage is controlled by voltage controller during the whole working process. In the grid-connected mode, voltage controller keeps power balance with microgrid load and makes a stable output, meanwhile an additional current controller is introduced to regulate output current and keep power balance between microgrid and the grid. In islanding mode, the current controller quits from working, and the load voltage is still maintained by voltage controller. So the power can be balanced and the output of controller is continuous. Besides, the control mode has been transferred to voltage control mode seamlessly. According to the described collaborative control of voltage and current, a voltage controller and a current controller are designed. Finally, simulations using Simulink and experiments show that the collaborative control of voltage and current can realize seamless transfer of microgrid.