不对称故障下考虑故障时间的储能变流器动态电压支撑策略研究

Research on Dynamic Voltage Support Strategy for PCS Considering Fault Time under Asymmetric Faults

电网发生不对称故障会造成公共连接电压(Point of Common Coupling,PCC)跌落、储能变流器(Power Conversion System,PCS)输出电流幅值增大等不利影响,严重时可能引起PCS切机.针对上述问题,提出了一种不对称故障下的PCC电压动态支撑策略.首先,分析了不对称故障下PCS的运行特性,得到了电压支撑方程;然后,根据并网标准划分了故障穿越运行区域,基于电压支撑方程和故障穿越运行区域设计了PCC电压动态支撑方案;同时对PCS输出电流幅值进行限制,在保证电压支撑效果和容量充足的情况下,进一步对负序电压进行抑制;最后,在Matlab/Simulink中验证了所提策略的有效性.

The occurrence of asymmetric faults in the grid can cause adverse effects such as a drop in the point of common coupling(PCC) and an increase in the output current amplitude of the power conversion system(PCS),which may cause the PCS to cut out in severe cases.To address the above problems,this paper proposes a PCC voltage dynamic support strategy under asymmetric faults.First,the operating characteristics of PCS under asymmetric faults are analyzed,and the voltage support equation is obtained.Then the fault-ride-through operation area is divided according to the grid connection criteria,and the PCC voltage dynamic support scheme is designed based on the voltage support equation and the fault ride-through operation area,while the PCS output current amplitude is limited to further suppress the negative sequence voltage,ensuring the voltage support effect and sufficient capacity.Finally,the effectiveness of the proposed strategy is verified in Matlab/Simulink.