Application Study For Erosion Optimized Diagnosis Measure Of Grounding Grid Of 220kV Renhe Substation In Chongqing

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. This approach has a little blindness and heavy workload and 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 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.The feasibility and accuracy of this method is proved by lots of emulation 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 are 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 and separated scales measurement is suitable to the grounding grid. During the measurement, 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.Based on a large number of simulation experiments, the 220kV Rehen substation were measured at the scene, according to the results of corrosion diagnosis, compared with the grounding grid of targeted excavation and the blind-wide excavation of the station for the economy, we can see that grounding grid corrosion in the diagnosis of the actual application of engineering have huge advantage.The method for erosion optimized diagnosis of grounding grid offers an accurate and practical optimized diagnosis method for substation grounding grid erosion without power cutting and digging large area. It reduces the blindness and the workload, and improves the safety and reliability of power system operation. This method not only can diagnose the old substations erosion quickly and accurately, but also can ensure the quality of the new substation grounding grid. Putting this optimized diagnosis method into practice, it keeps very high diagnosis ratio to various fault of grounding grid. It satisfies the demand in practice.