电力电缆在电力系统中应用日益广泛，由于电缆绝缘老化和机械损坏等因素，随着运行时间增长，故障发生概率会有逐年增加的趋势。因此，对电力电缆在线故障测距的需求越来越紧迫。本课题通过对电力电缆故障测距的常用方法及新的故障测距技术进行系统分析比较，发现要实现小电流接地系统电力电缆在线故障测距，需要深入考虑以下几个问题：故障行波在传播过程中的特性；故障点的特性对故障行波的影响；故障特征在测量点的变化特性以及如何准确确定故障行波到达时刻。 本课题以10kV交联聚乙烯绝缘电力电缆为原型，用ATP/EMTP建立了一个电力电缆系统仿真模型，并仿真了不同故障接地方式下的故障电流波形特征，分析了故障点的特性对故障行波的影响。故障分析过程中采用小波变换局部模极大值的方法检测故障行波的突变点特征，通过小波的故障点奇异性判据判断是否发生故障，如果有故障发生则采用改进的测距算法计算出故障距离。另外，还分析了影响在线故障测距精度的因素和消除这些因素影响的措施。 为了测试论文研究的可用性，设计了电力电缆故障测距数据处理系统。数据处理系统硬件主要包括DSP工作电路设计、A/D转换电路设计、电源模块电路设计、存储器模块电路设计、逻辑模块电路设计。数据处理系统软件以DB小波作为故障行波时刻检测算法，以D-S证据推理方法作为电缆系统故障类型分类算法，在CCS IDE中编写了程序，与硬件联机调试证明该算法具有一定的可行性，可以达到预期的效果。

Power cable is applied in power system extensivly. Probability taking place in cable fault is greatly increased along with run-time, as many factors, such as power insulation aging and machinery damage. On-line fault location technologies are urgent need in power cable systems.In this paper, on-line fault location method and new technologies are analyzed and compared systematically. Several important and difficult problems should be thought of carefully about on-line fault location in cable power system, which transformer neutral point not directly grounded. Firstly, what's the characteristic of the traveling wave during its propagation; Secondly, will the fault point characteristic affect the traveling wave; Thirdly, how will the fault information change at the measuring point; And the last but not the least, how to determine accurately the arrival time of the traveling wave. A sample power cable system is created, with a transient simulation tool ATP/EMTP (Alternative Transient Program) based on a 10kV XLPE (Cross-linked Polyethylene) cable model in the paper. Under this model, the characteristic of fault current is simulated in different fault grounding modes. Fault point characteristics are simulated to determine their effect to traveling wave. The break point characteristic of fault traveling wave is found by using wavelet transform and local module maximum method, and judged the question whether or not the fault is happened by the criterion of fault traveling wave singularity. If that’s ture, the fault distance is worked out with the improved arithmetic of fault location. Moreover, the factors affecting the on-line location accuracy is discussed, and the means which eliminate the influence also is canvassed. For the usability of testing the thesis and studying, design a data processing system for XLPE cable fault location. The hardware of the system mainly including DSP (Digital Signal Processing) minimal system design, A/D conversion circuit design, power supply module design, the memory module circuit is designed, and the logical control module circuit is designed. Data processing systems soft mainly including an algorithm to pick-up the arrival time of the traveling wave based on db (daubechies) wavelet, and D-S (Dempster Shafer) decision-theoretic approach as the categorised algorithm for XLPE cable. Compiled the program in CCS IDE (Code Composer Studio Integrated develop environment), and thus to validate the feasibility of on-line fault location by on-line debug.