【作者】 陈立；

【导师】 彭敏放；

【作者基本信息】 湖南大学 ， 电气工程， 2010， 硕士

【摘要】 发、变电站接地网对于电力系统的可靠运行和工作人员的人身安全起着重要作用。由于接地网常年埋在地下,因腐蚀、导体连接处的虚焊或漏焊等造成接地体断裂,使得接地网的电气性能参数恶化,严重时将直接危及电网的安全运行。因此,研究在发、变电站不停电和不对地网开挖的情况下,检测地网导体的断点,以及时发现故障隐患,防止由于接地不良造成的危害,对保障电力系统安全可靠运行以及运行人员的人身安全具有重要的意义。本文较详细地介绍了两种典型的接地网断点诊断方法,即电网络诊断法和电磁场诊断法。在分析此两种方法的特点、局限性及其诊断准确率的影响因素的基础上,探讨了改善或消除其影响因素的方法。同时,还研究了蒙特卡罗方法在电网络诊断算法评价中的应用,并分析了接地网断点故障的可测性,为本文后续章节合理利用诊断算法及其诊断结果提供了指导。然后,运用Matlab分别以电网络诊断法与电磁场诊断法,对接地网断点故障进行了仿真计算。结果表明,在对接地网导体的一些特殊断点诊断上,两种方法的诊断结果存在不一致性。为了提高接地网断点诊断准确率,本文探索性地将信息融合技术引入接地网断点诊断中,构建了接地网融合诊断模型,提出了其综合决策策略及其实现方案。在此基础上,提出了基于D-S证据理论的接地网断点诊断方法。该法以电网络诊断法、电磁场诊断法的诊断结果为证据来源,引入隶属度函数计算证据体的可信度分配,实现了对接地网断点故障的融合诊断。模拟诊断结果表明,与单一诊断方法相比,融合诊断结果的可靠性得到了明显提高。更多还原

【Abstract】 Grounding grids play a vital role to ensure the stable operation of the electrical power system and the safety of operators in power substations and plants. Corrosion phenomenon of grounding grids buried in soil exists generally. Serious corrosion of grounding grids will induce the grounding body rupture, inadequate hot stabilities, grounding parameters worsen, and so on. Accodingly the safety and stability of the power system will be in danger directly. Therefore, it is quite urgent and important to develop a method to diagnose breakpoints in grounding electrode without excavation or power off in time, in order to take corresponding defensive measures and prevent the hidden troubles happening.By analyzing weaknesses of existing two diagnosis approaches for breakpoints in grounding grids, which are based on circuit network method and electromagnetic field method respectively, some improvement measures are proposed. Also, this paper studies the application of Monte Carlo method in the evaluation of circuit network diagnosis algorithm and the testability analysis of breaking points diagnosis for grounding grids, which are usful for reasonable utilization of the diagnosis algorithm and diagnosis results in the subsequent chapters. Then, simulations for breakpoint diagnosis in grounding electrodes are carried out by using the two apprcaches respectively. The results show the disagreement in some special diagnosis of breaking points in grounding grids.In order to improve the diagnosis efficiency and accuracy, information fusion technology is introdued, for the first time, into breakpoints diagnosis of grounding grid. The model of fault diagnosis based on information fusion is built. Based on it, D-S evidence theory is applied to breakpoint diagnosis in grounding electrodes. Taking the results from the two above-mentioned approaches as sources of the evidences and using membership function to realize probability assignment of evidence bodies, fusion diagnosis is performed. Simulation results show that the proposed method is more effective than the previous.更多还原