【作者】 王硕；

【导师】 刘渝根；

【作者基本信息】 重庆大学 ， 电气工程， 2006， 硕士

【摘要】 接地网对保证变电站安全运行至关重要。由于接地网埋设在地下,以往工程上一般通过大面积开挖检查接地网的腐蚀情况。这种方法带有盲目性,工作量极大,影响电力系统的运行。一些专家学者对接地网的腐蚀诊断在理论上已有所研究,但诊断方法用于实际工程的一些技术问题还没有解决。本文所研究的中大型接地网腐蚀优化诊断方法是将故障诊断学原理、网络理论、矩阵理论及计算机算法结合起来,应用于接地网腐蚀诊断这一工程实际问题。利用接地网拓扑结构图及接地网引下线间的电阻测量值,建立腐蚀诊断方程,通过求解诊断方程,计算出接地网支路电阻值变化量,采用模糊诊断方法判断出接地网导体腐蚀的情况。采用VB语言和Matlab软件相结合的方法编写了《接地网腐蚀诊断软件》。通过大量仿真计算,验证了本方法的可行性和准确性。利用ATPDraw软件搭建起良好的模拟试验平台可以准确快速的计算出接地网任两节点对间电阻值,在这一平台上准确模拟实际接地网参数,结合软件进行了大量模拟试验,总结出中大型接地网优化诊断方法:采用初步测量与再次补测相结合的方法效率很高;在初步测量时,对中型接地网宜采用大跨距测量法;对大型地网则采用大分块结合不动点测量的方法效果较好。初步测量节点数的选择以接地网节点总节点数的10%为宜,另应充分考虑接地网可能腐蚀的区域,重要电气设备区域、接地引下线分布等情况。采用优化的初步测量方法后,整个诊断所需的测量节点对数约为30%.进行了典发110kV、邮亭220kV、人和220kV变电站现场实测。使用直流双臂电桥,采用四端钮连接法,可大大降低现场中电磁干扰及引线电阻和接触电阻的误差影响。通过仿真计算、模拟试验和现场试验得到的接地网导体故障程度划分,可较准确地判断出接地网均压导体或引下线腐蚀程度和施工时漏焊虚焊点。中大型接地网腐蚀优化诊断方法在不停电和不进行大面积开挖条件下,为变电站接地网腐蚀情况,提供了准确实用的优化诊断方法,从而大大减少了接地网腐蚀诊断的盲目性和工作量,一定程度上提高了电力系统运行的安全可靠性。该方法不但能够对运行多年变电站的接地网腐蚀状况进行快速准确诊断,对新铺设地网的质量验收也有着实际意义。现场实际应用表明,优化诊断方法对中大型接地网中的各种故障都有很高的诊断率,各方面已初步达到工程实用的要求。更多还原

【Abstract】 The grounding grid is vital to the safety of the substation. As the grounding grid is underground, large-scale digging was adopted to find the erosion in practice all along. It is blind ,difficult. It influences the system operation. It has been studied about the grounding grid erosion diagnosis theory, but a lot of engineering technologies have not been solved on putting the method into practice.Based on fault diagnosis theory, network theory, matrix theory and computer arithmetic, a method of optimized erosion diagnosis for medium or large-scale grounding grid is discussed in this paper. According to the topology of the substation and resistance measurements of down-leaders, the erosion diagnosis equation is built and the resistance variations of grounding grid branches are solved, and the erosion of grounding grid could be found through the fuzzy diagnosis regulation.Based on VB and Matlab, diagnosis software for erosion of grounding grid is coded. The feasibility and accuracy of this method is proved by lots of emulational computations. The resistance between two nodes can be measured accurately and quickly on the nice simulative platform which is established using ATPDraw. The parameters of the grounding grid in practice is simulated on this simulative platform, and lots of simulative experiments were done. The method for erosion optimized diagnosis of medium or large-scale grounding grid is concluded: Elementary diagnosis integrating with supplementary diagnosis is efficient. During the elementary diagnosis, long span measurement is suitable to medium-scale grid. Big separated scales integrating with standing node when do elementary diagnosis is a good method to large-scale grounding grid. The number of the nodes for elementary diagnosis is ten percent of the total grid nodes number. And the erosible grid areas, important electrical equipments areas and the down-leaders areas should be considered enough. After this method is putted into practice, the number that total diagnosis nodes is thirty percent of the total grounding grid nodes.110kV Dianfa, 220 kV Youting and 220 kV Renhe substation grounding grid erosion optimized diagnosis experiments are done in practice. This paper selects dc double-arm bridge, uses the four-port connection to remove the contact and connection resistances and reduce the electromagnetism interfere. Grounding grid conductors fault levels are established during a lot of emulational computations ,simulative experiments更多还原