AN IMPROVED ALGORITHM OF CORROSION DIAGNOSIS FOR GROUNDING GRIDS & ITS EVALUATION

An improved algorithm of corrosion diagnosis for grounding grid is put forward. By shifted the positions of the current exciter within the touchable nodes and measured the voltages as many as possible for each excitation, the few touchable nodes are made full used of and the number of equations is enlarged remarkably. An augmented diagnosis equation to describe the nonlinear relationship between incremental branch resistances and incremental node voltages of touchable node is established, and an iterative algorithm is constructed to solve the nonlinear equation progressively by a series of linear equations. The least squares solutions of such linear equations are obtained by optimization method. The distances between each two vectors of the normalized augmented diagnosis equation are used to determine the number of independent equations, according to which, various testing methods can be evaluated in quantity. Effect of measurement error on the diagnosis results is also discussed. Results of calculation, analysis and measurement on practical examples show that the proposed method is feasible.