共查询到19条相似文献,搜索用时 187 毫秒
1.
2.
3.
4.
基于电磁感应原理的变电站接地网腐蚀诊断方法 总被引:8,自引:0,他引:8
为提高变电站接地网腐蚀诊断的效率和精度,提出一种新的诊断方法。基于有限元方法,计算激励电流在地表激发的磁感应强度,通过仿真计算,分析土壤结构对地表磁感应强度的影响;通过接地网的两下引导体直接注入和抽出异频的正弦波激励电流,基于电磁感应原理测量地表磁感应强度分布,诊断网格导体腐蚀变细和断点故障;结合变电站实际的电磁干扰环境,设计磁感应强度测量系统。实验和现场检测结果表明所提方法简便、有效,诊断系统满足测试需要,可用于工程实际。 相似文献
5.
6.
7.
针对使用钢材制作接地网易产生腐蚀而导致寿命更短,变电站需定期检测接地网是否存在缺陷的问题,设计了一套用于接地网缺陷的高精度磁场测试装置。通过对某35kV变电站接地网的检测,验证了该装置的精度和灵敏度良好,可靠性高,可定位接地网缺陷的位置。 相似文献
8.
9.
10.
11.
12.
13.
14.
Ramamoorty M. Narayanan M.M.B. Parameswaran S. Mukhedkar D. 《Power Delivery, IEEE Transactions on》1989,4(4):2053-2059
An analytical method to determine the transient performance of grounding grids is presented. In the proposed method, the leakage current to ground of each element of the grounding grid is represented more realistically than by considering the grid as an equivalent circular plate. Vertical ground rods of the grid are also considered. The maximum voltage to which a station grounding grid is raised due to incident impulse current can be determined. This is an important criterion in evaluating the transient performance of substation grounding grids which are generally designed from the point of view of power frequency fault currents. It has been found from both analytical and field studies that, in cases where impulse current injection is at the corner of the grid, the voltage induced and hence the impulse impedance are the highest. If the impulse current is incident at any other location within the grid, the grid exhibits a lower value of impulse impedance. Comparison of analytical results and field results shows good correlation for maximum induced voltages and impulse impedances 相似文献
15.
16.
变电站接地网的频域有限元方法 总被引:4,自引:0,他引:4
变电站接地网的安全性问题已成为电力系统电磁兼容的重要研究课题之一。文中基于有限元方法,将接地网一维导体单元与三维土壤单元相耦合,并考虑导体阻抗的频变特性,研究变电站接地网的接地性能。与三维有限元的A-V方法相比,该文计算方法的计算量大大降低,同时可以考虑频率对接地网接地性能的影响。通过与矩量法和测量结果进行比较,验证了该计算方法的正确性和有效性。利用计算得到的接地网导体轴向电流和土壤泄漏分布电流,进一步计算了接地网产生的空间磁场强度。结果表明,文中方法与矩量法的计算结果略有差异,原因在于矩量法中未考虑土壤泄漏分布电流的影响,文中计算方法可以方便地应用于复合土壤结构的接地网的接地性能分析。 相似文献
17.
考虑到配电网馈线自身阻抗及三相耦合作用的影响,对基于有源逆变器的单相接地故障全补偿零残流消弧算法进行了深入分析,并提出了改进思路。推导了全补偿故障消弧时有源逆变器的等效注入电流公式,表明有源消弧注入电流是由故障相电压和短路点的零序输入阻抗唯一确定。分析了有源电流和有源电压消弧算法,提出需利用消弧线圈电流折算、故障过渡电阻测量、单相接地故障区段定位等方法优化有源电流消弧算法;可通过监测负载电流和定位单相接地故障位置来优化有源电压消弧算法。研究结果对配电网单相接地故障有源消弧方法的改进提供了重要的理论依据。 相似文献
18.
Calculating output impedance in linear networks without source nulling or load disconnect: the instantaneous output impedance 下载免费PDF全文
A. S. Elwakil B. J. Maundy 《International Journal of Circuit Theory and Applications》2016,44(1):98-108
This paper derives exact expressions for the output impedance of a voltage‐excited (current‐excited) linear network without having to nullify (kill) the exciting source or disconnect the load. The derived expressions show that the instantaneous output impedance is both source and load dependent, but when the source is nullified, the output impedance becomes independent of the load, as expected. For some special networks, the output impedance is also independent of the load. The expressions are verified for a number of known circuit setups and experimentally on a gyrator‐based linear network, which has an output impedance that can switch between positive and negative values. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
19.
分析了消弧逆变器等效负载的性质,结果表明:等效负载是有源负载,等效源具有较大的幅值和较宽的变化范围;随过渡电阻和故障距离的变化,等效负载阻抗可呈现阻性、阻感性和阻容性。这一结果表明逆变器需要在负载性质改变和等效电源扰动的情况下,仍能稳定跟踪包含多频次的给定电流。对抗扰性和跟踪性要求的提高,增加了设计难度。鉴于此,提出了消弧逆变器输出滤波器和控制器的设计方法。输出滤波器采用滤波电容分流法进行设计,保证了逆变器能输出包含多频次的电流。采用电容串联电阻来抑制阻感负载情况下带来的谐振失稳问题,并给出了串联电阻的计算方法。控制器采用了定带宽设计法,带宽选定在幅频特性重合段。控制器参数设计准则为:保证阻容负载情况下传函幅频特性低频段具有较高增益。采用PSCAD/EMTDC仿真验证了结论的正确性和所提设计方法的可行性。 相似文献