Research On Calculation Method Of Three-dimensional Electric Field Of Transmission Line Based On Charge Simulation Method

With the continuous coupling of communication network and power grid,All-Dielectric Self Supporting(ADSS)optical cable,as a vital carrier of information transmission in the power system,has been widely used in the construction of power communication systems.In the process of construction,ADSS optical cable is often built on the same tower with high-voltage transmission lines.However,the electric field induced by these transmission lines will cause the electrical corrosion on ADSS optical cable.Therefore,selecting the appropriate hanging point position for ADSS optical cable has become an important measure to guarantee the safe operation of the power communication system by calculating the electric field generated nearby the transmission lines.In summary,based on the theory of Charge Simulation Method(CSM),this thesis studies the calculation method of space electric field near transmission lines.The main contents of this thesis are as follows:First,based the theory of CSM,this research proposes a theoretical model for calculating the three-dimensional electric field of the transmission line.The model takes the sag generated by transmission lines into account and uses the flat parabola equation to establish the physical model;put forward the definition of fitting accuracy,the transmission line model is discretized non uniformly based on this to reduce the influence of human error factors;according to the discrete results,line charges are set into the model at equal angular intervals,and the calculation formula of the two-dimensional electric field is obtained by establishing the independent twodimensional coordinates for line charges;using the principle of space geometry derives the calculation formula of the three-dimensional electric field.The simulation results show that the calculation model can effectively reduce the potential error of the calibration point on the electrode surface and improve the calculation efficiency.Then,to solve the problem that CSM is limited by human experience when setting simulated charges,this research completes the design of swarm intelligence optimization scheme based on CSM.In this scheme,the position and magnitude of the charge element are set as the key optimization variables,the average potential error function at the matching point is set as the fitness function in the optimization algorithm,and the optimization objective is to minimize the error.To measure the optimization effect of different algorithms combined with CSM,Particle Swarm Optimization(PSO),Gravitational Search Algorithm(GSA),Grey Wolf Optimizer(GWO),Whale Optimization Algorithm(WOA),and Sparrow Search Algorithm(SSA)are combined with CSM respectively,which are verified on three established electrode systems,ball-plate,ball end round rod-plate and finite-length straight wire.The simulation results show that the optimization effect of SSA with CSM is better than others.Finally,for better solving the three-dimensional electric field calculation problem of transmission lines with complex model structure,in this research,An Improved Sparrow Search Algorithm(ISSA)is proposed,which is used to the proposed three-dimensional electric field calculation model of transmission line.In ISSA,the improved sine chaos strategy is introduced to enrich the diversity of population,the proposed dynamic proportional factor of population identity and the adaptive step size adjustment strategy are used to adjust the global and local search ability of the algorithm,and a mutation disturbance strategy based on Tanimoto similarity is proposed to help the algorithm get rid of the trap of local optimization.The corresponding benchmark function simulation results show that ISSA has better optimization performance.When combined with the three-dimensional electric field calculation model of the transmission line,the distance from each line charge to the axis of the transmission line is taken as the optimization variable,and the ISSA is used to complete the optimal configuration of the simulated charge.This method is successfully applied to calculate the space electric field of the220 k V three-phase single circuit transmission line built on the 2B7-ZMC2 "cat head" tower.and According to the electric corrosion protection criteria of ADSS optical cables,a reference hanging point position is selected for ADSS optical cables.