基于复合型虚拟阻抗与自适应下垂控制的并联逆变器功率均分策略

对于因线路阻抗的不同而引起的并联逆变器输出无功功率不能实现精确均分的问题，提出了一种基于虚拟阻抗法的改进自适应下垂控制技术。此方法采用了一种新型的复合型虚拟阻抗，增加了下垂控制微调补偿和自适应下垂控制系数两个环节。通过引入此虚拟阻抗，不仅可以消除各支路阻性阻抗的影响，也能使得各支路阻抗感性成分达到近似相同，从而减小并联支路之间的阻抗差异。同时，改进的下垂环节可以进一步降低并联逆变器之间的无功误差。最后，仿真结果验证了此方法可实现快速和稳定的无功功率均分，减小了环流，提升了对无功功率均分的精确度，提高了系统的动态响应速度，使得并联逆变器稳定运行。

Power Sharing Strategy of Parallel Inverter Based on Complex Virtual Impedance and Adaptive Droop Control

For the problem that the output reactive power of parallel inverters cannot be accurately divided due to the difference of line impedance, an improved adaptive droop control technology based on the virtual impedance method is proposed. A new type of composite virtual impedance is adopted in this method, and two links, the fine tuning compensation of droop control and the adaptive droop control coefficient, are increased. By introducing this virtual impedance, not only can the influence of the resistive impedance of each branch be eliminated, but also the impedance sensitivity components of each branch can be approximately the same, thus reducing the impedance difference between parallel branches. At the same time, the improved droop link can further reduce the reactive power error between parallel inverters. Finally, the simulation results show that this method can realize the fast and stable averaging of reactive power, reduce the circulation, improve the accuracy of averaging of reactive power, improve the dynamic response speed of the system, and make the parallel inverter operate stably.