Abstract: Because of its large scale, complex structure and strong electromagnetic interference, the grounding grid of the substation has the problems of difficult detection and large error in corrosion diagnosis. Aiming at these problems,this article proposes a method based on the combination of electromagnetic field theory (EFT) and earth surface potential (ESP) to diagnose the corrosion conductor of grounding grid,so as to make up for the defect of poor measurement accuracy of EFT method under strong magnetic interference. This method first analyzes the magnetic induction intensity distribution of the corroded conductor on the basis of EFT. Then the paper analyzes the ESP distribution of the corroded conductor, combines the magnetic induction intensity curve with the ESP distribution curve, and finally determines the location and type of conductor corrosion. The test shows that the position of the corroded conductor obtained by this method is consistent with the position of the set corroded conductor, which shows the accuracy of the method in diagnosing the corroded conductor.

Key words: grounding grid corrosion, electromagnetic field theory (EFT), corrosion diagnosis, earth surface potential (ESP)