基于信号距离的变电站接地网故障诊断

发布时间：2018-11-12 16:02

【摘要】：变电站内良好的接地对保护站内工作人员的安全和电气设备的稳定运行至关重要。变电站接地网是电力系统高低压电气设备及继电保护自动装置的工作接地、保护接地、雷电保护接地的统一,为变电站内各种电气设备提供了一个公共的电位参考地,不仅可以起到均压的作用,并且当系统遭受雷击或发生短路故障时还可以泄放故障电流,控制接地网的最大电位升高,从而确保人身和设备的安全。接地网埋深于地下,由于土壤的长期作用而造成接地网网格导体腐蚀变细甚至断裂,当系统遭受雷击或发生短路故障时,可能引起事故的扩大,带来巨大的经济损失。在我国对接地网的故障排查通常采用大面积开挖的方法,这种检测方法虽然简单,但盲目性大,且会影响变电站的正常运行。因此目前电力系统迫切需要寻求一种在不开挖接地网、不影响变电站正常运行的条件下,对接地网导体的缺陷位置及其缺陷状态进行诊断,并能够评估接地网安全性能的实用、有效的诊断方法。本文重点对变电站接地网网格导体的缺陷诊断方法做了详细的研究,主要工作如下:1、利用CDEGS接地分析软件,建立接地网仿真模型,基于电磁感应原理,对搭建的接地网注入异频的正弦波激励电流,仿真分析地表磁感应强度分布,根据分布特征对接地网网格导体的缺陷状态进行诊断;2、分析了土壤分层结构、注入电流位置和接地网网格导体结构对地表磁感应强度分布的影响,并研究了接地网导体腐蚀变细和断裂情况下地表磁感应强度的分布规律;3、当接地网网格导体腐蚀变细和断裂情况下,对地表磁感应强度分布进行比较分析,基于信号距离函数,通过Matlab编写接地网故障诊断程序,计算地表磁感应强度分布之间的互距离函数值,找出波形之间的具体差异,从而对接地网故障进行诊断。
[Abstract]:Good grounding in the substation is very important for the safety of the staff and the stable operation of the electrical equipment. Substation grounding network is the unity of grounding, protection grounding and lightning protection grounding of high and low voltage electrical equipment and automatic relay protection device in power system, which provides a common potential reference place for all kinds of electrical equipment in substation. It can not only play the role of voltage balance, but also release the fault current when the system is struck by lightning or short circuit fault, and control the rise of the maximum potential of the grounding grid, thus ensuring the safety of the person and equipment. The grounding grid is buried deeper than the ground, and the corrosion of the grid conductor becomes thinner or even breaks due to the long-term action of the soil. When the system is struck by lightning or short circuit fault, it may cause the expansion of the accident and bring huge economic losses. In our country, the method of large area excavation is usually used in the fault detection of docking ground network. Although this method is simple, but blind, it will affect the normal operation of substations. Therefore, at present, the power system urgently needs to seek a practical way to diagnose the defect position and the defect state of the ground grid conductor without excavation and without affecting the normal operation of the substation, and to evaluate the safety performance of the grounding grid. An effective diagnostic method. In this paper, the fault diagnosis method of grounding grid conductor in substation is studied in detail. The main work is as follows: 1. Using CDEGS grounding analysis software, the simulation model of grounding grid is established, based on the principle of electromagnetic induction. Based on the sinusoidal excitation current injected into the grounding grid, the distribution of magnetic induction intensity is simulated and analyzed, and the defect state of the grid conductor is diagnosed according to the distribution characteristics. 2. The effects of soil stratified structure, injection current location and grid conductor structure on the distribution of magnetic induction intensity are analyzed, and the distribution of magnetic induction intensity in the case of corrosion thinning and fracture of grounding grid conductor is studied. 3. When the grounding grid conductor becomes thinner and ruptured, the distribution of magnetic induction intensity is compared and analyzed. Based on the signal distance function, the fault diagnosis program of grounding grid is compiled by Matlab. The mutual distance function between the magnetic induction intensity distribution on the ground surface is calculated and the concrete difference between the waveforms is found so that the fault diagnosis can be carried out by docking the ground network.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM862;TM63

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