A Method For Erosion Optimized Diagnosis Of Medium Or Large-scale Grounding Grid

The grounding grid is vital to the safety of the substation. As the grounding grid is underground, large-scale digging was adopted to find the erosion in practice all along. It is blind ,difficult. It influences the system operation. It has been studied about the grounding grid erosion diagnosis theory, but a lot of engineering technologies have not been solved on putting the method into practice.Based on fault diagnosis theory, network theory, matrix theory and computer arithmetic, a method of optimized erosion diagnosis for medium or large-scale grounding grid is discussed in this paper. According to the topology of the substation and resistance measurements of down-leaders, the erosion diagnosis equation is built and the resistance variations of grounding grid branches are solved, and the erosion of grounding grid could be found through the fuzzy diagnosis regulation.Based on VB and Matlab, diagnosis software for erosion of grounding grid is coded. The feasibility and accuracy of this method is proved by lots of emulational computations. The resistance between two nodes can be measured accurately and quickly on the nice simulative platform which is established using ATPDraw. The parameters of the grounding grid in practice is simulated on this simulative platform, and lots of simulative experiments were done. The method for erosion optimized diagnosis of medium or large-scale grounding grid is concluded: Elementary diagnosis integrating with supplementary diagnosis is efficient. During the elementary diagnosis, long span measurement is suitable to medium-scale grid. Big separated scales integrating with standing node when do elementary diagnosis is a good method to large-scale grounding grid. The number of the nodes for elementary diagnosis is ten percent of the total grid nodes number. And the erosible grid areas, important electrical equipments areas and the down-leaders areas should be considered enough. After this method is putted into practice, the number that total diagnosis nodes is thirty percent of the total grounding grid nodes.110kV Dianfa, 220 kV Youting and 220 kV Renhe substation grounding grid erosion optimized diagnosis experiments are done in practice. This paper selects dc double-arm bridge, uses the four-port connection to remove the contact and connection resistances and reduce the electromagnetism interfere. Grounding grid conductors fault levels are established during a lot of emulational computations ,simulative experiments...