Grounding Grids Corrosion Diagnosis Using a Block Dividing Approach

For fault diagnosis,concepts of blocks and their prototypes,uncertain-branch groups and their prototypes,projection of blocks and part of touchable nodes are defined,and a new approach of diagnosing the fault of grounding grids by blocks is put forward.According to the desired fault diagnosis area,the blocks together with their projections and the parts of touchable nodes,which participate in the diagnosis,are determined.According to tested data of the corresponding parts,the resistances of intrinsic branches in a block can be determined by a linear least square method,by which the resistances of clear branches in the block can be worked out.The ranges of resistances of uncertain-branches in the block are also evaluated by a dichotomy algorithm.With the proposed approach,a grounding grid can be divided into several small-scale sub-grids.As a result,the efficiency is improved and the cross-interferences are reduced.An experimental grounding grid with thirty-eighty branches is used as an example.The results of fault diagnosis show that the proposed approaches are feasible,and only a few tests are needed to meet the requirements of diagnosing a certain part of the grounding grid.