Simulation And Experimental Study On Insulation Defects Of 66kV XLPE Power Cable

In order to adapt to the rapid development of society,XLPE power cables are widely used in power systems due to their excellent performance.Accidents caused by insulation defects in the cable body and cable joints account for most of the total cable accidents.Therefore,it is necessary to study the relevant insulation defects to provide a basis for maintenance and inspection.First of all,this thesis not only expounds the fault types and causes of power cable accessories in detail,but also clarifies the principle that the electric field and temperature field affect the insulation performance of the cable,and analyzes and summarizes the formulae of the finite element software to calculate the electric field and temperature field.Secondly,when there are different defects in the cable terminal joint and the cable intermediate joint,the electric field and temperature field are simulated and calculated,and combined with some numerical theoretical analysis,the law of local electric field intensity distortion inside the joint caused by different insulation defects is obtained.Discharge or even insulation breakdown;excessive current-carrying capacity of the terminal and the presence of impurities inside the terminal will cause the local temperature rise inside the cable to be too high;the temperature rise inside the intermediate joint and the temperature rise of the external environment are approximately linear.Then,the electric field simulation is carried out for the defects of regular and irregular damage of the insulation shielding layer of the cable body,and the factors affecting the degree of electric field distortion under such defects are analyzed,and the defects after the outer sheath and metal shielding are analyzed.The influence law of the circumcision outer sheath on the degree of electric field distortion is verified,and the common problems related to this in production practice are verified.Finally,insulation defects are designed in the laboratory and experiments are carried out,and it is concluded that the initial discharge voltage of the surface discharge model and the impurity discharge model is lower than that of the other two models,and it is easier to discharge.It proves the correctness of the simulation.