【作者】 黄海鲲；

【导师】 关根志；

【作者基本信息】 武汉大学 ， 高电压与绝缘技术， 2004， 硕士

【摘要】 交联聚乙烯(XLPE)电力电缆由于其自身的一系列优点，在高压电网中得到了越来越广泛的应用。特别在城市中，由于电网结构的调整和城市规划的要求，电缆线路不断增加。目前已有不少110KV电压等级的交联聚乙烯电力电缆线路投入运行，并且处于快速增长的趋势。对运行中的电缆，为了掌握其绝缘状况，有必要对之进行在线的绝缘监测及诊断。110KV电压等级的电缆线路在城市电网中的地位举足轻重，更加应该给予重视。 本论文首先概要地讨论了目前电力电缆绝缘在线监测的几种方法，并对这些方法进行分析、比较，指出它们的优缺点。从这几种在线监测方法中归纳出它们的实质：在线监测实际上是进行一系列电参量的检测，并以实验得到的先验数据与实际电缆绝缘特性之间的相关性为依据来判断电缆绝缘的状况。 目前采用的多种在线监测方法都是针对较低电压等级的电缆线路。对于较高电压等级的电缆，本文通过对绝缘参数的估算得出结论：几种已有的针对较低电压等级电缆的在线监测方法，难以有效地用于110KV的XLPE电缆绝缘在线监测。论文进一步指出，局部放电法与趋势管理方法是电缆绝缘在线监测的发展方向。虽然局部放电方法的有效性较高，但价格投入甚高。故本文通过对具体的电缆线路进行分析，采用接地线电流法作为趋势管理的手段。既可达到一定的效果，又可体现经济上的优势。 针对接地线电流法，设计并完成了一套现场多路接地线电流采集装置，包括传感器的选择，输入信号的放大，前置低通滤波，锁相环频率跟踪电路的设计以及基于AT89C55的单片机的数据采集、键盘与液晶显示等电路的设计。本文将介绍在开发过程中的一些思路以及一些实际问题的相应解决对策。 同时，本文简要地介绍了用来进行趋势管理的上位机的定时监控程序，以及基于RS485的串口通信的实现和数据库的建立等。 对采集并存储到上位机数据库中的时间序列，进行了统计分析。对采集得到的三相电流信号实现单相历史数据的纵向比较以及三相电流之间的横向比较，并综合起来对绝缘的老化状况进行评估。更多还原

【Abstract】 XLPE power cable is widely used in grid system for its series of merits. Especially in cities, for the requirement of network structure adjustment and city planning, the mount of cable line increases continuously. At present, there are many XLPE cable lines of 110KV voltage class in service and it is on the swift growth trend. For the power cables in service, it is necessary to carry out on-line insulation monitoring and diagnosis so as to master its insulation condition. The cable lines of 110KV voltage class take an important place in city power grid, so we should pay more attention to it.In this paper, we generally discuss several existed methods about on-line insulation monitoring on cable. Then analyze and compare these methods and figure out their merits and demerits. We also induce their essential: to carry out on-line monitoring is to detect a serial of electric parameters, then base on the correlation of prior data coming from experiment and insulation character of actual cable, we can assess the cable insulation condition.At present, most of the on-line monitoring methods aim at cable line of low voltage level. For those of high voltage level, after the estimate of their insulation parameters we draw the conclusion that those above methods cannot apply to on-line insulation monitoring of 110KV XLPE cable. The paper also points out that partial discharge method and trend management method are the trend of development. Although the validity of partial discharge method is high, its price is relatively higher. So we chose earth line current for trend management. It can achieve certain effect and is economical.As for earth line current method, we designed and finished a set of on-site multi-path earth line current correcting device. This work include the choice of current transformer and the design of amplifier, prior low pass filter, frequency tracing circuit with phase loop, data acquisition based on AT89C55 MCU, keyboard and LCD display module. This paper also discuss in detail about some thoughts in the development process and solution for some actual problems.We also briefly introduce the timing monitor program in upper computer that is used for carrying out trend management and the realization of serial port communication based on RS485 and the establishment of database.We collect the data and save them to database on upper computer. Then we form a time series data and proceed statistic analysis. We longitudinally compare the historical data of certain phase and crossly compare the date phase-to-phase. We combine their results to evaluate the condition of cable insulation.更多还原