基于抑制环流的自适应下垂控制改进策略

在孤岛模式下的微电网中由于线路阻抗存在差异，采用传统下垂控制的逆变器不仅无法精确分配负载功率，还会产生环流。为解决该问题，提出了一种基于抑制环流的自适应下垂控制改进策略。该策略采用旋转坐标的环流来构造虚拟阻抗，通过PI控制使线路等效阻抗不断相向趋近直至相等，从而均衡分配负载功率。所提出的改进策略无需实时检测线路阻抗，也无需借助通信网络。此外，构造的虚拟阻抗不仅能有效抑制环流，还不会引起输出电压大幅跌落。仿真结果验证了改进控制策略的有效性。

Improved Strategy for Adaptive Droop Control Based on Suppressing Circulating Current

In the microgrid in an island mode, the inverter under the traditional droop control cannot accurately distribute load power due to the difference in line impedance, and it will also generate circulating current. To solve this problem, an improved strategy for adaptive droop control based on suppressing the circulating current is proposed. The circulating current in a rotating coordinate system is used to construct the virtual impedance, and the PI control is used to make the equivalent impedance values of the line continuously approach each other until they are equal, so as to balance the distribution of load power. This improved strategy does not need to detect the line impedance value in real time or rely on a communication network. In addition, the constructed virtual impedance can effectively suppresses the circulating current while avoiding a large drop in the output voltage. Simulation results verify the effectiveness of the improved control strategy.