Optimization Design Of Grounding Grid For 220kV Substation

In order to ensure safe and stable operation of the equipment in the substation,prevent lightning equipment and person,the grounding system in substation should have excellent safety performance and reasonable design parameters.Important parameters of grounding grid include grounding resistance,contact voltage,and stride voltage,etc.Before design grounding grids,we must base on actual situation of local soil structure and soil resistivity to reducing grounding resistance.At the same time we should base on local conditions to change the structure of the grounding grid,the material,etc.to reducing contact voltage and step voltage as far as possible.Firstly,this paper analysis the significance of reducing the resistance,contact voltage and stride voltage of grounding grid in substation.At the same time,the rationality of the grounding grid design method is evaluated.By summing up the requirements and technical requirements of relevant laws and regulations,summing up practical experience,combining the operation mode of the system and the specific condition of the electrical equipment,the specific requirements and principles of the grounding grid design and the design process are obtained.On this basis,this paper studies the calculation method of important parameters such as transformer substation's resistance,mutual resistance coefficient,grounding grid potential,contact voltage,step voltage,grounding material consumption and so on.Analysis and compare the calculation methods of the same parameters,on this basis,the optimal calculation method and mathematical model are obtained.Research on the method of grounding grid resistance reduction which provide the basis for the optimum design of grounding grid.In order to solve the problems in designing traditional grounding grid,an improved Particle swarm optimization(PSO)algorithm is proposed.By using this algorithm,the optimal compression ratio in unequal spacing grounding grid is obtained.This algorithm not only solves the optimization problem of multi-objective function including grounding grid resistance,contact voltage,step voltage and investment cost,but also provides a basis for optimizing the design of substation grounding grid.Design Yongling 220 kV substations combined with the above methods.According to the parameters of the grounding grid and the soil parameters,calculate ground resistance,surface potential,contact voltage and cost expectation of horizontal grounding grid with unequal spacing,unequal distance horizontal grounding grid combined with vertical grounding electrode,unequal interval grounding grid combined with external grounding grid.Through 3D graphics simulation of surface potential and contact voltage in Yongling 220 kV substations,The optimal design scheme of the substation is obtained.