Research on Corrosion Diagnosis of Grounding Grid Based on Lasso Theory
The limited available test endpoints of the grounding grid,being deep underground,result in the number of equations obtained from testing being far less than the number of branch resistances to be solved,leaving corrosion diag-nostic equations seriously underdetermined that are difficult to be solved.Following the establishment of the grounding grid model based on the electrical network theory,the grounding grid corrosion diagnosis equations were established by using the Tellegen's theorem,and a solution method was proposed for the underdetermined equations of the grounding grid corrosion diagnosis based on Lasso theory.By introducing a penalty term,the influence of the resistance change of of less corroded branches was suppressed,reducing the uncertainty degree of the equation system.After iterative calcula-tion,the change of the branch resistance of the grounding grid was obtained,based on which the corrosion position and degree of corrosion of the grounding grid of the substation were diagnosed.The simulation and experimental results show that the diagnosis method based on the Lasso theory can accurately solve the resistance value of the grounding grid branch by using fewer port network equations,providing a new method for accurate and convenient diagnosis of the cor-rosion of the grounding grid of the substation.
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