孤岛微网虚拟同步发电机不平衡电压控制策略

Unbalanced Voltage Control of Virtual Synchronous Generator in Islanded Microgrid

在分析虚拟同步发电机带不平衡负载运行特性的基础上,提出改进的虚拟同步控制策略。在虚拟同步功率控制环后增加机端电压控制环,并在同步旋转坐标下对机端电压进行分序控制,实现机端电压三相平衡。利用虚拟阻抗对线路阻抗引起的负序电压降进行补偿,实现母线电压三相平衡。改进后的控制策略保留虚拟同步发电机的特性,实现孤岛微网虚拟同步发电机带不平衡负载时母线电压三相平衡,提高虚拟同步发电机供电质量。通过仿真及实验验证所提控制策略的正确性及有效性。

Analyzing the operating characteristics of the unbalanced load with virtual synchronous generator, an improved virtual synchronization control strategy is proposed.The terminal voltage control loop is increased, and the terminal voltage is worked under the synchronous rotating coordinate sequence control to realize the three-phase balance of terminal voltages.After that, the virtual impedance is used to compensate the negative sequence voltage drop caused by the line impedance to achieve three-phase bus voltage balance.The improved control strategy preserves the characteristics of the virtual synchronous generator, keeps the bus voltage three-phase balance as the islanded microgrid with unbalanced load, and improves the quality of power supply virtual synchronous generator.The correctness and effectiveness of the proposed control strategy are verified by the simulation and experiment.