Modeling Of Grounding System And Resistance Reducing Measure In Complicated Soil Structure

The substation or converter station grounding system is important to ensure the reliable operation of power system, so the design of substation or converter station grounding system is also an important issue. With the development of electric power system capacity, the value of failure current flowing into ground increased obviously. Particularly, the earth-fault current of ultra-high voltage converter station is even to 30kA . How to design the grounding system to make the parameters meet regulations requirements is a key problem of engineers, the soil structure is the base of grounding system. In the past, the way to fix these problems is considering the soil structure as uniform or horizontal two-layer soil, however, it would take unnegligible errors especially in complicated soil structure, so it's very important to build correct soil model. And during these years, grounding module, which is one of the resistance reducing measures, was extensively used in resistance reducing design of grounding system. Therefore, it's necessary to study the soil structure of grounding system and resistance reducing measure.In this thesis, the heterogeneous soil of main area was studied by grounding software firstly, summarizing the rules under different influence factors and giving out corresponding treating methods. Secondly the volume weighted average method was used to compute the backfill soil resistivity of Chuxiong±800kV ultra-high voltage converter station, then soil delaminated and blocked would be applied to design the soil structure. Then figuring out the important parameters of converter station by the data like built soil structure and so on. Finally, make the grounding system meet the safety requirements.As an important way to reduce grounding resistance, nonmetal grounding module was introduced in this thesis. Researching the influence caused by different ratio to its self-resistivity and impact grounding resistance by experiments. Summarizing the installation suggestion of grounding module under different influence factors by software simulation, which is valuable to engineering application.