Research Of Grounding Grid Fault Diagnosis And Partition Diagnosis Based On Electrical Impedence Reverse Problem

Substation grounding grid is an important guarantee for the reliable and safeoperation. The metal conductor of grounding grid is perennial buried in the soil.Grounding short-circuit current is increasing with the development of the powersystem. There are more and more problems with the grounding grid. If the groundinggrid is serious corrosion, the electric potential uplift would do damage to the primaryand secondary equipment and threaten the normal operation of the power system. Tothis end, many scholars at home and abroad do a large number of studies on the faultdiagnosis of grounding grid, including the electrical network theory methods andmagnetic field diagnosis methods.In this paper, the method of fault diagnosis of grounding grid based on reverseproblem is proposed and the sensitivity equation is proposed. The partition diagnosismethod is proposed on the base of the sensitivity method. These methods are verifiedthrough simulations. A cycle voltage measurement based on the four-electrode isproposed and the grounding grid fault diagnosis system is designed including themeasuring device and fault diagnosis software. The main contents are as follows:①The regularization algorithm to solve the grounding grid fault diagnosisequation is proposed. Several different regularization form and the L-curve method toselect the regularization parameter are researched. The feasibility of the method isverfied by simulations. The noise immunity of the algorithm and differentmeasurement mode results are analyzed.②The sensitivity equation of the grounding grid fault diagnosis using LSQRregularization algorithm is proposed. The feasibility of the algorithm is verified bysimulations. The partition diagnosis method based on the sensitivity method isproposed. The method is verified by a variety of grounding grids simulation analysis.③In order to reduce the contact resistance and lead resistance for voltagemeasurement, a four-electrode voltage measurement method is proposed, and a16-channel voltage loop measurement is proposed to achieve auto-excitation andmeasurement and to improve measurement efficiency.④A grounding grid fault diagnosis software is designed to model the groundinggrid, automatically measuring, fault diagnosis and results display.⑤The accuracy of fault diagnosis algorithm and the reliability of the fault diagnosis system are verified through the resistance grid and steel mesh experiment.The feasibility of the algorithm and system is verified through the grounding grid in asubstation.