A New Method of Grounding Grid Fault Diagnosis Based on Grounding Conductor Soundness

To improve the accuracy of fault diagnosis of substation grounding grid, an actual 35 kV substation grounding grid is tested and studied. At the beginning, when the grounding grid is under initial and normal condition, its surface potential and magnetic induction intensity are calculated and measured. These results are kept as historical standard data. Thus, the distribution rules of surface potential and magnetic induction are concluded. According to these rules and researches done before, a new diagnosis index, called grounding conductor soundness, is proposed based on grey relational degree theory. Then, typical faults are set artificially on the grounding grid to simulate fault conditions. And the surface potential and magnetic induction intensity of the grounding grid are measured again. The accuracy of the new method is illustrated by the fault diagnosis test of this grounding grid. The results have shown that the proposed diagnosis index can be used to diagnose the grounding grid’s fault type and location accurately. This research may provide new idea and important supplement for the fault diagnosis and state evaluation of substation grounding grid.