The Corrosion Diagnosis Method Of Grounding Grid

Good grounding system is critical to maintain the power system security. It is animportant method to ensure the safety of operating persons and electricalequipments.However, the corrosive effect of the soil may cause the ground lead andthe average voltage conductor thinning and rupture, and then may lead to thespreading of the accident when the system ground fault occurs. This would endangerequipment and personal safety. In the past, we used the method of excavation a largearea to check and detect the corrosion of the ground network. This approach is notonly inaccurate, but also with a lot of blindness workloads, and it may affect thenormal operation of the power system.In this paper, firstly, we use the method of Monte Carlo to generate corrosionslip randomly, and use unequal potential model which is based on field-circuitcoupling theory to calculate the resistance of grounding grid. Then we determine thenetwork whether needs to be diagnosed by analyzing the variation in resistance value.This completes the determination of the diagnosis of the necessity. Then groundinggrid corrosion diagnosis equations are established by using the application ofelectrical network theory, and fault branch’s position are determined by solving theoptimal solution of the underdetermined corrosion diagnosis equations withregularized least squares method. After this, we verify the accuracy of the diagnosisequation, the diagnostic equations rationality, and diagnostic accuracy throughexperiments. Finally, we study the influence of touchable nodes deviation ongrounding grids corrosion diagnosis, and propose amendments of the program tosolve this problem.In this article, we program diagnostic necessity analysis procedures with theMatlab language, and determine the degree of grid corrosion by calculating theresistance of the grounding grid. After we judged the necessity of diagnose, we build grounding grid equivalent model with ATPDraw software to analog ground networkcorrosion. We input the measured node voltage into the fault diagnosis procedures toobtain the location of the fault.The effectiveness of corrosion diagnosis method is verified through a lot ofsimulations. This method has some practical value, not only on corrosion groundnetwork which has run for many years, but also on the quality and acceptance of thenew ground network.