Research On Grounding Scheme Of 220kV Substation Considering GPR And Grid Optimization

Substation grounding system is an important part of substation.The operation state of grounding system is closely related to safe operation of power grid,the safety of equipment in case of accident and personal safety.Combined with the project of 220 kV substation,this paper mainly studied the problems of relaxing GPR safety limit of substation grounding system,grid optimization of equidistant and unequal spacing arrangement of horizontal grounding pole,and resistance reduction optimization problem.Firstly,it is proposed that the safety limit of GPR should be considered in the design of 220 kV substation grounding system,and the safety limit of GPR is analyzed.EMTP is used to establish a simulation model of GPR striking 35 kV arrester under short-circuit fault.Through modeling and calculation,the GPR safety limit of this station is obtained.On the other hand,in order to calculate the ability of secondary cables to resist electromagnetic harassment,the transfer impedance of secondary cables is obtained through experimental measurement and theoretical analysis,and the disturbance voltage of secondary cables is calculated,so as to obtain the safety limit of substation GPR.Combining the two aspects of research content,the smaller value of GPR is the safety limit that can be relaxed.Secondly,according to the operation parameters of substation grounding system,the uniform grid layout,the optimal compression ratio method,and the Gaussian method are used for grid optimization.The optimization results of three grid layout optimization methods are analyzed.By comparing the optimal compression ratio layout and the contact voltage on the diagonal of grounding system under the gaussian function layout,the optimal layout scheme is obtained.Finally,the resistance reduction effect of oblique grounding pole in unif orm soil and double-layer soil is simulated,and the arrangement rule of oblique grounding pole in uniform soil and double-layer soil is obtained.The simulation results show that the grounding performance of the 220 kV substation cannot meet the requirements when using the conventional grounding system.Combined with the research conclusion in chapter 2,both the contact voltage and the stepping voltage are reduced to some extent after the gaussian function method is used to optimize the grounding system,but it still cannot meet the requirements without laying high resistance layer.From chapter 3,the grounding system GPR can be extended to 20 kV,grounding resistance can be extended to 1.3?,reason for 220 kV substation grounding system are analyzed in drag reduction.Considering the arrangement around the grounding system 12 root 50 m long slanting grounding resistance reduction is carried out on the net,the performance meet the design requirements of grounding system scheme.