摘  要

随着我国经济的迅速发展，城网、农网的改造，电力电缆因其安全、可靠、有利于美化城市、优化厂矿布局等优点，在我国获得了广泛的应用，并在原有线路的基础上发展了越来越多的电缆–架空线混合线路。由于制造工艺不完善、运行环境恶劣和产品质量缺陷等原因，经常会引起电缆的绝缘水平下降，造成电缆运行故障。因为架空线上的绝缘子质量不过关、遭到外力破坏等原因，也常常造成线路故障，这些故障多为永久性故障。当电力线路发生故障后，对故障进行快速定位，准确地测定出故障点的位置，对于尽快恢复供电、提高供电企业经济效益具有重要作用。电力线路发生故障后，通过测距技术寻找故障点，对于快速故障排查是一种有效的措施。但是电缆–架空线混合的线路的大量应用，由于混合线路的参数在各段不统一，已有的测距方法的应用受到了一定的局限。因此，深入研究混合线路故障测试方法，开发相应的测试系统具有重要的意义和实用价值。

电缆–架空线混合线路故障测距是电力线路故障点定位的重要内容，是保证故障能否快速排除的关键。针对行波测距在电缆–架空线混合线路应用中存在的问题，本文将展开以下的研究工作：

（1）分析行波在电缆–架空线混合线路中的传播规律以及目前行波测试方法的原理，利用 ATP/EMTP 对不同故障类型及测试方法进行仿真和分析，为进一步的故障测距研究打下基础。

（2）研究小波阈值去噪的方法及阈值的确定问题。通过对比分析不同阈值时候的消噪效果，寻找适合线路故障测距的小波阈值确定方法。

（3）研究故障点距离的计算方法。针对电缆–架空混合线路上行波信号在连接处发生突变的特点，找到合适的计算电缆–架空混合线路故障距离的方法。

（4）搭建电力电缆–架空线故障测距系统，实现故障信号的消噪和奇异点检测，实现电缆–架空线混合线路的故障测距。

关键词：电缆；架空线；混合线路；故障；测距

Abstract

With the rapid development of our country’s economy, the transformation of urban network and agricultural network, the power cable has been widely used in our country because of its advantages of safety, reliability, favorable to beautifying the city and optimizing the layout of factories and mines. More and more hybrid cable-overhead lines have been developed on the basis of the original lines. Due to the imperfect manufacturing process, poor operating environment and product quality defects, the insulation level of the cable is often reduced and the cable operation failure is caused. Because the insulator on the overhead line is not up to standard and is destroyed by external force, it often causes the fault of the line, most of which are permanent faults. When the power line breaks down, After that, it is very important to locate the fault quickly and determine the location of the fault point accurately, which is very important to restore the power supply as soon as possible and improve the economic benefit of the power supply enterprise. It is an effective measure to find fault point through location technology after fault of power line occurs. However, because the parameters of the hybrid line are not uniform in each section, the application of the existing ranging methods has been limited due to the extensive application of the cable-overhead line hybrid line. Therefore, it is of great significance and practical value to study the fault test method of hybrid line and develop the corresponding test system.

The fault location of the cable – overhead line hybrid line is an important part of the fault location of the power line, and it is the key to ensure the rapid removal of the fault.

1) analyzing the traveling wave propagation law in the cable-overhead line hybrid line and the principle of the current traveling wave testing method, using ATP/EMTP to simulate and analyze the different fault types and test methods, so as to lay a foundation for further fault location research.

The method of wavelet threshold denoising and the determination of threshold are studied. By comparing and analyzing the de-noising effect of different threshold, the wavelet threshold determination method suitable for fault location of transmission line is found.

The calculation method of fault point distance is studied. In view of the sudden change of traveling-wave signals on cable-overhead hybrid lines, a suitable method for calculating the fault distance of cable-overhead hybrid lines is found.

4) to build the fault location system of power cable and overhead line, to realize the noise elimination of fault signal and the detection of singularity, and to realize the fault location of cable-overhead hybrid line.

Keywords: cable; overhead line; hybrid line; fault; location

目  录

摘  要 I

Abstract II

1绪论 1

1.1课题的研究背景和意义 1

1.2故障测距方法的提出和发展 2

1.3 故障测距研究面临的难题 2

1.3.1各类别测距方法的比较 2

1.3.2两类故障测距方法需要解决的问题 4

2行波法测距的基本原理 5

2.1电力线路的暂态行波过程 6

2.1.1行波的基本概念 6

2.1.2线路的行波过程分析 8

2.2 行波传输特性分析 10

2.2.1行波的反射系数与折射系数 10

2.2.2行波在母线处的反射 12

2.2.3行波在故障点处的反射 14

2.2.4对端母线处的反射 14

2.3行波法故障测距的基本原理 15

2.3.1行波信号中的故障距离信息 15

2.3.2行波法故障测距的主要技术问题 15

2.3.3新型单端行波故障测距原理 16

2.3.2新型双端行波故障测距原理 18

3小波变换工具与数学形态学运用原理 20

3.1小波变换基础理论 20

3.1.2小波变换的定义 21

3.1.3模极大值原理检测信号的奇异性 22

3.2数学形态学基础理论 23

3.2.1数学形态学原理与算法 23

3.2.2运用形态学来反映信号的奇异性 25

3.3数学形态学和小波变换在实际工程应用中的差异 26

3.4小波变换在测距中的应用 27

3.4.1排除噪声干扰 28

3.4.2基于小波变换的故障选线 29

3.4.3运用小波变换进行线路上的行波故障测距 29

4新型行波测距的建模仿真 30

4.1仿真工具介绍 30

4.1.1 Simulink模型 30

4.1.2数据处理 31

4.2故障测距软件设计 31

4.2.1相模变换 32

4.2.2小波变换 32

4.3新型单端测距方法建模仿真 33

4.4新型双端测距方法建模仿真 38

参考文献 45

致  谢 47

附录   程序清单 48

1故障行波分量的提取程序 48

2小波分析消噪程序 49

3小波分析在信号奇异性中的检测应用 50

4小波变换求模极大值波形主程序 51