基于虚拟同步机控制技术的交直流互联电力系统电压稳定控制策略

摘要

电压暂降是电力系统正常运行过程中一种不可避免和难以预测的电能质量问题.交直流微电网和交直流配电的发展,使交直流互联方式下交流电网电压稳定问题更加复杂.针对电压暂降治理,提出了一种采用虚拟同步发电机技术的交直流互联方法.根据本文提出的方法,光伏发电和电池储能等直流分布式系统,能自主地参与到对交流电网电压的调节中,从而维持交流母线电压的稳定性.设计并搭建了额定功率为120 kVA的仿真平台,对上述控制策略进行了仿真分析和研究,仿真结果验证了所提出控制策略能确保交流母线电压在电网电压暂降早期不会出现较高幅值的跌落,并在电网电压暂降故障排除后较快地恢复其额定幅值.%Voltage sag is a power quality issue which is one of the inevitable and indeterminable phenomena during the normal state of power system.The development of AC and DC microgrids,AC and DC distribution systems make the stability problem of AC grid voltage much more complicated in an AC-DC hybrid interconnected power system.Focus on the countermeasure of voltage sag problem,a control method to interconnect the AC and DC systems is proposed,which is based on the virtual synchronous generator technique.Based on the proposed control method,the DC distribution systems,such as photovoltaic power generation systems and electric battery devices,can autonomously participate in the regulation of AC grid voltage,and maintain the stability of AC-bus voltage.A simulation platform with rated at 120 kVA is designed and set up.The simulation results verify that the proposed methods can avoid the large decline of the ac bus voltage in the early stage of voltage sag,and make the AC bus voltage recover with a quite fast speed when the fault of voltage sag is excluded.