基于电流微分初始值的VSC直流配电系统线路故障定位方法

Line fault location method of VSC-based DC distribution system based on initial current differential value

在分析基于电压源型变换器的直流配电系统线路发生单、双极故障时电压、电流时域及频域故障特性方程的基础上,推导得到电流微分方程,并利用不同故障类型下的正极、负极电压和电流突变量进行故障判别,根据故障电流微分初始值推导得到故障定位方程。通过联立回路方程解决过渡电阻问题,并利用插值算法对传统的差分算法进行改进,解决了差分算法替代微分值存在的要求采样频率高、误差大的问题。仿真结果验证了所提定位方法的正确性和可行性,表明了所提方法计算简单、定位精度高。

Based on the analysis of time domain and frequency domain fault characteristic equations of voltage and current when pole-to-ground fault and pole-to-pole fault occur in the line of voltage source converter-based DC distribution system, current differential equation is deduced, fault is distinguished based on the positive and negative voltage and current variation of different types of fault, and the fault location equation is obtained according to the initial differential value of fault current. The problem of transition resistance is solved by simultaneous circuit equations and the traditional difference algorithm is improved by interpolation algorithm, which solves the high required sampling frequency and big error when differential algorithm replacing differential value. Simulative results verify the correctness and feasibilitY of the proposed location method and show that the proposed method is simple to calculate with high location accuracy.