随着电网规模的不断扩大，电缆故障的发生也越来越频繁。但是，到目前为止，国内外较成熟的电缆故障测距方法大都基于离线状态，电缆在线故障测距仍缺少有效的方法。因此，实现电缆在线故障测距，具有迫切的现实意义。本文以小波理论为基础，对电缆在线故障测距方法、电缆故障系统建模、故障仿真等方面进行了深入的研究，并开发了电缆在线故障测距装置。 论文首先介绍了小波分析的基本概念，从多尺度分析和模极大值特性的角度出发，对电缆在线故障测距方法进行了理论性研究，并利用MATLAB6.5软件建立电缆故障系统模型。大量仿真算例表明选用小波变换作为时频分析工具，能够有效的对电缆故障暂态行波进行分析，且不受故障位置、故障类型及过渡电阻的影响，具有较高的测距精度。针对波速不确定性影响电缆故障测距精度的问题，论文提出并推导了一种不受波速影响的电缆前后半程的测距公式，在理论上消除了波速对故障测距精度的影响。 论文随后根据电缆故障暂态行波的实际特点，完成了电缆在线故障测距装置的软硬件设计。硬件设计共分为3部分：一是由电流互感器和运放组成的信号调理电路实现I/V变换；二是由TMS320LF2407A DSP作为主CPU的高速数据采集电路，该电路采用DSP内嵌的A/D和SCI模块实现模数转换及数据通讯，并外扩LCD模块实现数据显示；三是由PC机作为系统的上位机实现数据分析、处理和存储等功能。软件设计共分为2部分：一是由C和汇编语言混合编写的下位机程序，主要完成系统初始化、中断采样、数据显示和数据通讯等工作；二是由VB语言和MATLAB语言编写的上位机后台分析软件程序，主要完成数据实时传输、数据文件保存、图形绘制、小波分析、频谱分析以及数据库开发等工作。 论文最后对电缆在线故障测距装置进行了各项测试。测试表明，该系统硬件和软件设计正确，满足电缆在线故障测距的要求，系统运行正常。

With the development of electric power industry, the possibility of the cable fault occuring is also becoming more and more greatly. However, up to now, the mature technology for cable fault location is mostly based on off-line at home and abroad. There are not efficient methods for calbe fault location on-line, so this topic has an exigently realistic significance. In this paper, the methods of cable fault location, system modeling and fault simulation are researched deeply based on the wavelet, after, the development of the cable fault location system are determined. At first, this paper introduce the theories of wavelet, research on method of cable fault location on-line from the multiscale analysis and module maximum, and model the cable fault by using MATLAB6.5 software. A great many simulations show that the wavelet transform can effectively analyze the transient traveling wave, and be immune to the fault location, fault type and transition resistance, and enhance the accuracy of location. Aiming at the problem of the uncertainty of wave speed which influence the accurace of location, the fore-and-aft fault distance expressions that avoid the wave speed influence in theory are worked out. Then the designing and application of the hardware and software of cable fault location system are performed in this paper. The hardware designing includes there parts: The first one is the signal adjustment circuit which is made of the current transformer and operational amplifier that achieves I/V transform; The second one is hign-speed sampling circuit which uses the TMS320LF2407A as the main center processing unit, at the same time, the embedment ADC, SCI and extension LCD module are acquising, transmitting and displaying data. The third one is PC computer as the upper computer of system. The software designing includes two parts: The first part is the front computer procedures which are compiled by C and assemble language that can achieve many works about system initialization, interruption acquisition, displaying data and transmitting data. The second part is the upper computer procedures which are compiled by VB language and MATLAB language that can accomplish some assignments about real time transmission of data, image-based rendering, file saving, wavelet analysis, spectrum analysis and data bank development. Finally, the system is tested in this paper. The test results show that the hardware and software can normal work and meet the requirements of cable fault location on line.