毕业设计-动力电缆断点检测与定位装置的设计与实现.doc

ABSTRACT 摘要 PAGE 46 PAGE 45 摘要 电力电缆断线故障测距技术己经基本成熟，架空线路在线故障测距技术也日趋成熟并开始得到广泛地推广应用，虽然电力电缆在线故障测距技术还不成熟，但是电力系统对电力电缆在线故障测距的需求却越来越急迫。要实现电力电缆的在线故障测距，必须考虑的几个难题是:中性点非直接接地系统是否能产生有效的故障暂态行波；故障信息在传播过程中的特性；故障点的特性对故障行波的影响；故障信息在测量点的变化特性；如何准确确定故障行波到达时刻等。 本文分析了行波故障测距方法的特点，明确了各类行波故障测距方法的优缺点。在比较了行波测距法与阻抗测距法的基础上，发现行波测距法优于阻抗测距法，因此采用低压脉冲法实现故障测距。 关键词：电力电缆；行波；故障测距 Abstract ABSTRACT Off-line fault location for power cable and on-line fault location for overhead transmission line have been accomplished in the past several decades. Nowadays power cable systems are in great need of on-line fault location technologies .Before achieving. this goal, several important and difficult problems should be thought of carefully .First, whether or not can effective traveling wave due to cable fault be found to locate the fault point in cable system whose transformer neutral point not directly grounded? Second ,whats the characteristic of the traveling wave during its propagation? Third, will the fault point characteristic affect the traveling wave ? Fourth ,how will the traveling wave change at the measuting point? And the last but not the least ,how to determine accurately the arriveal time of the traveling wave. This paper analyses the traveling wave the characteristics of fault location ,and we know lines of the various methods of wave fault location advantages and disadvantages。In comparing the line-ranging law and the impedance ranging law, on the bast of we found in the power cable fault location in line-ranging method is better than the impedance ranging law ,we decision used to low-voltage pulse method to achieve fault location. Key words: power cables; traveling wave; fault location 目录 目录 目 录 TOC \o 1-3 \h \u 第1章 引言 1 1.1 课题研究的背景及意义 1 1.2 电力电缆发生故障的原因与类型 2 1.2.1 故障原因 2 1.2.2 故障类型 3 1.3 电缆故障测距概述的现状 4 1.3.1 阻抗法 4 1.3.2 行波法 5 1.3.3 其他方法 7 1.4 本章小结 7 第2章 低压脉冲回波法的原理及液晶显示LCD1602 9 2.1 低压脉冲回波法的原理 9 2.2 液晶显示模块LCD1602 10 2.3 本章小结 12 第3章 555定时器及其单稳态电路 13 3.1