Modeling And Reducing Resistance Measures Of Grounding System In Complex Soil

Good and safe grounding system for the normal operation of the power system and personal safety is essential,so the grounding problem of power system has been the concern of people at home and abroad.The first thing to consider is the soil model when designing a grounding system,because the soil model selection determines directly the grounding system design results.Grounding resistance has been the main parameter of grounding system research,but also the hotspot of research.For some areas of high soil resistivity,grounding resistance can often not meet the requirements,so we need to take some measures to reduce resistance.Based on a large number of related literatures at home and abroad,in this paper the simulation to the complex soil grounding system has been carried by CDEGS and the research has been carried from the soil structure,electrical parameters and the resistance reduction measures.Firstly,the problem of model establishment with heterogeneous soil is established.A heterogeneous soil model is established by CDEGS software,heterogeneous when soil resistivity is higher and lower than the surrounding soil resistivity.Based on the model simulation,the effects of the surrounding soil resistivity,heterogeneous soil location,cross-sectional area and depth on the grounding resistance were simulated.Secondly,according to the actual engineering application,a substation is established in mountainous.The mountain model,the mountain top tower grounding model,the mountain top substation grounding model have been modeled.The influence of height of the mountain,the slope and the distance between the edge of the grounding grid and the edge of the mountain on grounding grid is studied.The simulation results show that the higher the height of the mountain,the greater the grounding resistance of the mountain top grounding system;the influence degree of the mountain slope on the grounding network is greater than that of the single grounding body,and the grounding resistance increases with the increase of the mountain slope,While the step voltage is gradually reduced;grounding resistance with the edge of the grounding grid and the distance between the edge of the mountain decreases.Finally,the external grounding resistance reduction and vertical grounding pole reduction are modeled by exploring how to resist resistance to high resistance area.The simulation results show that the effect of reducing grounding resistance with external grounding resistance reduction is obvious when there is a low soil resistancein the 1~2km from the main grounding grid;vertical grounding pole reduction method to reduce the resistance is more appropriate,if there is a low resistance area in the depth of the soil.