Research On Electric Field Distribution And Structure Optimization Of 220kV Cable Terminal Under Dynamic Parameters

220kV cable terminal will be aging under the influence of heat and other factors in the long running process.The electrical parameters and non-electrical parameters of the main insulation XLPE and enhanced insulation silicone rubber will change with the change of their aging degree.The distribution of electric field and temperature field in cable terminal operation is affected by material parameters such as main insulation XLPE and enhanced insulation silicone rubber conductivity,and these parameters will change with aging.In addition,there are many coupling relations between electric field,temperature and stress in cable terminal,such as electromagnetic heat and thermal expansion.Traditional theoretical analysis is complicated and requires a lot of calculation,so it is of great practical significance to use finite element simulation to analyze electric field distribution of 220 kV cable terminal under dynamic parameters under the influence of thermal aging and other factors.In this thesis,the 220 kV cable terminal produced by the manufacturer was purchased and samples of XLPE and silicone rubber materials were prepared to test the changes of material parameters of the two materials after different degrees of thermal aging.COMSOL Multiphysics simulation software was used to conduct 1:1modeling of cable terminals,and the material parameters tested in the test were inserted into the model.Based on the coupling of physical fields such as solid heat transfer,current and solid mechanics,the distribution of electric heating field and stress field of cable terminals during operation was analyzed.In this thesis,the location of cable terminal insulation weak point is analyzed by simulation results,and the structure optimization scheme is proposed to improve the electric field distribution in cable terminal.In addition,in order to comprehensively analyze the operating conditions of cable terminals under various conditions,this thesis carries out simulation analysis of cable terminal defects and installation misplacement.The results of thermal aging test of insulating materials show that the electrical conductivity and elastic modulus of insulating materials change dynamically with aging time increasing,and the electrical conductivity of silicone rubber material accords with the dynamic parameter formula trained by neural network.The simulation results show that the strongest and weakest point of the cable terminal is located near the truncation of the cable outer shield layer,and with the increase of aging time,the maximum field strength increases,the temperature of the fixed anchor point in the temperature field increases,and the stress of the fixed anchor point in the stress field decreases.In the case of cable terminal defects and misplacement,the field intensity distortion will occur in the internal area.After optimizing the cable terminal by using the method described in this thesis,the equal distribution of electric field intensity is relatively improved,which has certain reference value for engineering.