基于虚拟阻抗的微电网分布式无功分配策略

交流微电网孤岛运行时，分布式电源因线路阻抗差异的问题，导致传统下垂控制输出无功功率不能合理分配。为此，提出了一种基于自适应虚拟阻抗的分布式无功分配策略。分布式控制中，利用动态一致性算法得到无功信息，构建自适应虚拟阻抗以降低因线路阻抗不同造成的功率耦合，实现各分布式电源输出无功功率按容量比例分配。针对下垂控制输出电压偏差问题，引入电压补偿环节，使得输出电压恢复到额定值。所提策略构建的分布式控制无需进行全局通信，仅通过本地控制器与相邻控制器交换信息，即可得到全局无功信息。最后通过不同的案例分析仿真实验，验证了所提控制策略的有效性。

Distributed reactive power allocation strategy of microgrid based on virtual impedance

When the AC microgrid is operated in isolation, the distributed power sources cannot reasonably distribute the traditional droop control output reactive power due to the problem of line impedance differences. For this reason, a distributed reactive power distribution strategy based on adaptive virtual impedance is proposed. The distributed control uses dynamic consensus algorithm to obtain reactive power information, constructs adaptive virtual impedance to reduce the power coupling caused by different line impedances, and realizes the proportional distribution of the output reactive power of each distributed power supply according to its capacity. For the droop control output voltage deviation problem, a voltage compensation link is introduced to make the output voltage return to the rated value. The distributed control constructed by the proposed strategy does not require global communication, and global reactive power information can be obtained only by exchanging information between the local controller and the neighboring controllers. Finally, the effectiveness of the proposed control strategy is verified through different case study simulation experiments.