| The grounding grid plays an important role in ensuring the normal operation of the power equipment and the security of the staff in the substation.The deep buried grounding grid is prone to corrosion fault,and the performance of the corroded grounding grid is degraded,which poses a serious threat to the safe operation of the substation.Therefore,this paper is devoted to the research of fault diagnosis method of grounding grid.The existing fault diagnosis method based on magnetic field analysis needs a lot of magnetic field measurement data.In order to solve the problem,this paper proposes a hierarchical diagnosis method based on inversion diagnosis model,and develops a fault diagnosis system of grounding grid.In this method,the resistance of the grounding conductor is calculated by the inversion analysis of the magnetic induction intensity of the scattered surface measurement points,so as to measure the corrosion degree of the conductor.In order to further reduce the number of measurement points,the method defines the influence coefficient of the branch,and establishes the evaluation system for the difficult degree of diagnosis.Under the guidance of the evaluation system,the selection of measurement points is more pertinent,reducing the number of low efficiency measuring points,and the high accuracy diagnosis of corrosion is realized by the hierarchical progressive mode.In order to verify the effectiveness of this method,simulation and field experiments are carried out.The results show that the hierarchical diagnosis method can greatly reduce the number of measuring points and reduce the distribution range of measuring points.At the same time,the algorithm of inversion diagnosis model is also studied in this paper.Tikhonov regularization and IWOA are used to solve the inversion diagnosis model.Firstly,the discrete Picard criterion is used to analyze the ill-posed nature of the inversion diagnosis model,and finds that its ill-condition is serious.Therefore,Tikhonov regularization is used to modify the inversion diagnosis model and reduce its ill-condition.At the same time,the control parameter of WOA is made chaotic by β-chaotic mapping,which improves the global optimization ability of the original algorithm.Then the IWOA is used to solve the modified inversion diagnosis model,which improves the accuracy of the model solution.Based on the above research content,this paper designs and develops a fault diagnosis system of substation grounding grid.The diagnosis system can quickly build diagnosis model according to different structure of grounding grid,carry out hierarchical diagnosis,visualize diagnosis results and generate diagnosis reports.Finally,the system is used in the field diagnosis application test.The test results show that the system can make accurate and efficient diagnosis,and has a certain application value for the maintenance of substation grounding grid. |
