一种基于电流微分初始值的直流配电网故障定位方法

A Fault Location Method for DC Distribution Network Based on Differential Initial Value of Current

直流配电网故障定位是排查故障、确保线路安全的关键手段。基于此提出了一种基于电流微分初始值的直流配电网故障定位方法。首先推导了基于电压源型变换器的直流配电网线路发生双极短路故障和单极接地故障时故障电流的微分方程,并利用双极短路故障和单极接地故障中正负极线路的电压和电流突变量差异来判定故障的类型。其次通过电压源型变换器直流侧电容的放电过程提取故障电流信息,且根据限流电抗器上的电压降得到故障电流的微分等量表达式,并联立所推导的故障电流微分初始值方程获得故障定位的数学模型,从而实现故障距离的准确定位。最后利用PSCAD/EMTDC仿真平台搭建仿真模型,验证了所提故障定位方法的有效性。

Fault location of DC distribution network is an important approach to troubleshoot faults and ensure line safety.Based on this,a fault location method of DC distribution network based on the initial value of current differential is proposed in this paper.Firstly,the differential equations of the fault current of the DC distribution network based on the voltage source converter are derived when the bipolar short-circuit fault and the unipolar ground fault occur.Then,the fault types are determined by the difference of volt⁃age and current of positive and negative lines in bipolar short-circuit fault and unipolar ground fault.Secondly,the fault current information is extracted by the discharge process of the DC side capacitor of the voltage source converter,and the differential equivalent expression of the fault current is obtained according to the voltage drop on the current limiting reactor.On this basis,the mathematical model of fault location is obtained by the differential initial value equation of fault current derived simultaneously,so as to achieve fault location.Finally,a simulation model is built using the PSCAD/EMTDC simulation platform to verify the effective⁃ness of the proposed fault location method.