基于电压平衡器的低压直流系统单端故障测距方法研究

Research on Single-terminal Fault Location Method for LVDC System Based on Voltage Balancer

为解决低压直流系统传统单端测距方法求解过程对端量缺失的问题,本文设计了一种基于电压平衡器的单端注入测距方法。故障发生后,线路两端直流断路器动作断开故障线路,根据故障类型控制本端电压平衡器中绝缘栅双极型晶体管是否导通。随后投入测距装置,利用对端电压平衡器中绝缘栅双极型晶体管或续流二极管构成测距回路,根据基尔霍夫定律对正负极分别列写电压回路方程,利用中线的耦合求解故障距离,实现了精准测距。最后,在PSCAD/EMTDC中搭建了双端低压直流系统的模型进行仿真验证。结果表明,该方法故障定位精确、抗过渡电阻能力强,能够满足低压直流系统的故障测距要求。

To solve the problem of the missing quantity in the traditional single-terminal ranging method for a low-voltage DC(LVDC)system,a single-terminal injection ranging method based on voltage balancer is designed in this paper.After a fault occurs,the DC circuit breakers at both ends of the line act first to disconnect the faulted line,and the IGBT in the voltage balancer at the local end is controlled according to the fault type.Then,the ranging device is applied to form a ranging loop based on the IGBT or freewheeling diode in the voltage balancer at the opposite end.According to the Kirchhoff’s law,the voltage loop equations are written for the positive and negative poles separately,and the fault distance is solved by the coupling of the neutral line,thus realizing accurate ranging.Finally,the proposed method is simulated and verified by building a double-terminal LVDC system model in PSCAD/EMTDC.Results show that the proposed method can locate fault accurately and withstand the transition resistance strongly,which can meet the fault location requirements of LVDC systems.