采用地表电位和磁感应强度进行变电站接地网故障诊断的效果对比

Comparison of Substation Grounding Grid Fault Diagnosis Results Using Surface Potential and Magnetic Induction Intensity

为有效提高变电站接地网导体故障诊断的准确性,以某35 k V变电站为依托,基于量纲相似原理设计和定制了不规则形状的接地网模型,根据接地网模型的地表电位和地表磁感应强度的计算结果,通过模拟典型故障,对采用地表电位和磁感应强度诊断接地网典型故障的测试结果进行了对比,总结了接地网典型故障时地表电位和磁感应强度的变化规律,据此提出了基于灰色关联理论的接地网状态评价指标。结果表明,接地网导体节点处电位较高,网孔上方地表电位略低;导体上方磁感应强度较高,且激励电流注入点处的地表磁感应强度最大;所提出的接地网导体健全度评价指标可准确判断接地网故障类型和故障位置。

To improve accuracy of fault diagnosis of substation grounding grid, we have designed and customized a ran- dom form grounding grid model of a 35 kV substation based on dimensional similarity principle. According to the calculation results of the surface potential and magnetic induction intensity of the grounding grid, the test results of typical faults diagnosis of grounding grid based on surface potential and magnetic induction intensity are compared by simulating typical faults. The change rules of surface potential and magnetic induction intensity when grounding grid has typical faults are also summarized. A judging rule of grounding grid state is proposed based on the grey relational degree theory according to the change rules. The results show that the surface potential of conductors＇ nodes is higher, and the surface potential of mesh is lower. The magnetic induction intensity is larger, and the magnetic induction intensity of the current injection point is the largest. The proposed judging rule can be used to diagnose the grounding grid＇s fault type and location accurately.