配电网发生单相接地故障，故障距离的准确测量对修复线路故障、保证供电可靠性以及系统安全稳定的运行具有重要意义。当配电系统发生单相接地故障，只依靠行波的时域特征进行故障测距会存在误差，不能满足要求。因此，本文研究行波时频特性，构建测距方法，实现准确测距。 通过模量分析法对配电网发生单相接地故障的行波时域特征进行分析，利用线路微元等效模型分析行波在传播过程中各个物理量随频率的变化规律。可知，行波在传播过程中伴随能量的衰减，且传播参数是与频率相关的函数。 提出了一种含去噪因子的B-spline小波分析模极大值检测算法。通过对平稳小波变换后的小波尺度系数取极大值的方式，确定入射波到达母线测量点的时刻，并且引入去燥因子，避免了其他线路入射波以及系统噪声对波头检测的干扰，解决了以往小波变换对行波时域波头模极大值点检测不准确和抗干扰能力差的问题。 提出了基于改进矩阵束算法的行波频点信息提取方法。通过分解奇异矩阵前项奇异值与后相奇异值之比确定信号模态阶数，实现了对行波频谱的检测和波速度的准确匹配。 提出了基于行波时频特性的单相接地故障测距方法。利用基于B-spline小波分析的行波波头模极大值检测算法确定行波到达母线的时刻，根据改进矩阵束算法，提取行波到达母线测量端的频率，并根据频率得到相应的入射波波速,采用模量波速差的故障测距方程求解故障距离。 PSCAD/EMTDC建立配电网辐射状模型，模拟线路不同情况下的单相接地故障，通过MATLAB对数据进行处理，验证本文基于行波时频特性的配电网单相接地故障测距方法。仿真结果表明本文测距方法相较于传统方法测距误差减小，并且故障测距结果准确度较高。

Single-phase fault occurs in distribution network, and the accurate measurement of fault distance is of great significance for repairing line fault, ensuring power supply reliability and stable operation of the system. When the single-phase grounding fault occurs in the distribution system, which will be errors only relying on the time-domain characteristics of the traveling wave for fault location and can not meet the requirements. Therefore, the time-frequency characteristics of traveling wave is researched in this paper , the method of fault location is constructed and the accurate fault location is realized. The time-domain characteristics of single-phase grounding fault in distribution network are analyzed by modulus analysis, and the variation of each physical quantity with frequency in the process of traveling wave propagation is analyzed by using the line micro-element equivalent model. It can be seen that the energy attenuation of traveling wave is accompanied by the propagation process, and the propagation parameters are frequency-dependent functions. A modulus maximum detection algorithm based on B-spline wavelet function with denoising factor is proposed. By taking the maximum of the wavelet coefficients after the stationary wavelet transform, the time when the incident wave reaches the bus measurement point is determined, and the threshold k is set to avoid the interference of other line incident wave and system noise to the traveling head detection. Algorithm solves the problems of inaccurate detection of modulus maximum of traveling wave head and poor anti-interference ability of wavelet transform in the past. An improved matrix pencil algorithm is proposed to extract the frequency point information of traveling wave. The modal order of the signal is determined by the ratio of the singular value of the front term to the singular value of the back phase of the decomposed singular matrix, and the detection of the traveling wave spectrum and the accurate matching of the wave velocity are realized. The method of fault location based on traveling wave time-frequency characteristics is proposed. The traveling wave head modulus maximum detection algorithm based on B-spline wavelet analysis is used to determine the time when the traveling wave reaches the bar bus. According to the improved matrix beam algorithm, the frequency of traveling wave arriving at the measuring end of bar bus is extracted. According to the frequency, the corresponding incident wave velocity is obtained. The fault location equation of modulus wave velocity difference is used to solve the fault distance. The radial model of distribution network is built in PSCAD/EMTDC to simulate the single-phase grounding fault under different conditions of the line. Through MATLAB to process the data, the proposed single-phase grounding fault location method based on traveling wave time-frequency characteristics of distribution network is verified. The simulation results show that the fault method proposed in this paper reduces the fault location error compared with the previous methods, and the fault method proposed in this paper is accurate and effective.