我国配电网多为小电流接地方式，配电网发生单相接地故障的概率高达80%，发生单相接地故障后不及时处理会造成大范围停电，因此为了配电网的安全稳定运行，应及时隔离故障减少停电范围，研究单相接地故障快速准确定位问题具有重要意义。本文通过对暂态零序电流的趋势特征研究提出了一种新的区段定位方法。
       本文基于小电流接地系统单相接地故障的零序等效模型，对故障线路及健全线路、故障点上下游的单相接地故障暂态零序电流趋势特征进行了理论研究及仿真分析。研究结果表明，故障线路与健全线路暂态零序电流变化趋势相反，故障点上下游暂态零序电流变化趋势相反，且该变化趋势特征差异不受故障条件影响，并探讨了上下包络线的选取规则，为准确地进行故障区段定位提供理论依据。
       提出了一种暂态零序电流包络线拟合斜率的故障区段定位方法。该方法先利用分段三次埃尔米特插值法求取表示暂态零序电流变化趋势的包络线，再利用带可变遗忘因子的递推最小二乘法求取包络线的拟合斜率，由此构成拟合斜率向量并构建基于拟合斜率的区段定位判据，若拟合斜率向量中某个检测点上下游的元素正负相反，则该元素对应的即为故障线路或故障区段，否则判定为母线故障。
       为验证本文所提区段定位方法的适应性及可靠性，本文利用Matlab/Simulink 仿真软件建立10kV 配电网仿真模型，设置不同故障条件及中性点运行方式进行仿真验证；并利用实验室380V 配电网模拟实验平台，模拟不同的单相接地故障条件进行了实验验证。仿真及实验结果表明在不同故障条件下均可准确定位故障区段。

       Most of the distribution networks in my country are grounded with small currents. The probability of single-phase grounding faults in the distribution network is as high as 80%. Failure to deal with the single-phase grounding faults in time will cause large-scale power outages. Therefore, for the safe and stable operation of the distribution network, The fault should be isolated in time to reduce the scope of power outage, and it is of great significance to study the problem of fast and accurate location of single-phase grounding faults. In this paper, a new section location method is proposed by studying the trend characteristics of transient zero-sequence current.
       Based on the zero-sequence equivalent model of single-phase-to-ground faults in small-current grounding systems, this paper conducts theoretical research and simulation analysis on the trend characteristics of transient zero-sequence currents of single-phase-to-ground faults upstream and downstream of faulty lines, sound lines, and fault points. The research results show that the transient zero-sequence current of the faulty line is opposite to that of the sound line, and the change trend of the transient zero-sequence current upstream and downstream of the fault point is opposite, and the difference in the characteristics of the change trend is not affected by the fault conditions. It provides a theoretical basis for accurately locating the fault section.
       A fault section location method based on the slope fitting slope of transient zero-sequence current envelope is proposed. The method first uses the piecewise cubic Hermitian interpolation method to obtain the envelope representing the trend of transient
zero-sequence current, and then uses the recursive least squares method with variable forgetting factor to obtain the fitting slope of the envelope. , which constitutes the fitting slope vector and constructs the segment location criterion based on the fitting slope. If the positive and negative elements of the upstream and downstream elements of a certain detection point in the fitting slope vector are opposite, the corresponding element is the fault line or fault. section, otherwise it is judged as a bus fault.
       In order to verify the adaptability and reliability of the section positioning method proposed in this paper, this paper uses Matlab/Simulink simulation software to establish a 10kV distribution network simulation model, and sets different fault conditions and neutral point operation modes for simulation verification; The distribution network simulation experiment platform is used to simulate different single-phase ground fault conditions for experimental verification. Simulation and experimental results show that the fault location can be accurately identified under different fault conditions.