Investigation On The Corrosion Diagnosis Approaches Of Grounding Grids

To realize the corrosion diagnosis of grounding grids, two diagnosis methods including the sensitivity matrix and iteration based approach and Tabu Search based are investigated. The application software based on above two methods is developed on the platform of MATLAB. To solve the problem of the diagnosis results quite correlated with initial values, a hybrid approach combining simplex and Tabu search is put forward. The coal of the proposed approach is Tabu search, but the initial values are regulated by simplex. The diagnosis results are improved.A novel hierarchical simplification model of grounding grids is proposed to know the testability of grounding grids, in which, a grounding grid is described as six layers such as the actual grounding grid, quasi-circuit-blocks, circuit-blocks, block-networks, assessable grounding grid and intrinsic grounding grid. According to the testability, the branches are classified into clear-branches and uncertain-branches. The resistance of the former can be determined while the resistance of the latter cann't. A novel approach is presented to calculate the resistance of clear-branches by tracing from the intrinsic grounding grid to the upper layers. As for the uncertain branches, a method based on the dichotomy to calculate their possibility ranges of resistance is suggested. The possible upper and lower limits of resistances of an uncertain branch can be obtained quitely. The application software based on the proposed approach is developed on the platform of MATLAB.An experimental grounding grid with sixty branches is used as an example. The results of corrosion diagnosis show that the proposed approach and the developed software are feasible.