Study On Flashover Characteristics And Electric Field Distribution Of Insulators In High Altitude True Towers And Air GAP

Lightning is the main reason for the tripping of overhead transmission lines.The true lightning flashover characteristics of air gaps and insulators are the basis for lightning protection calculation and design of accurate transmission lines.The electric field distribution around the insulator is affected by the tower.Therefore,the study of the flashover characteristics of the insulator in the true tower is more analogous with the actual operating line.In addition,in the actual operation of the line,the influence of altitude conditions on the insulator's impulse discharge voltage is not negligible.Therefore,systematic test research on the flashover characteristics and differences of true tower insulators,single insulators and air gaps under high-altitude lightning strikes has important engineering application value and theoretical guiding significance.Firstly,the insulator and air gap flashover test observation circuit were designed.The flashover test platforms of insulator in true tower,single insulator and rod-plate air gap were built in the UHV engineering technology?Kunming?National Engineering Laboratory with an altitude of 2100 m.The flashover characteristics test of 2.2 m composite insulators in 220 kV true cup-tower under high altitude short-tail wave impact and the flashover test of 1m class rod-plate gap,composite insulator and glass insulator region under standard lightning wave impact were carried out.The U_50%,volt-second characteristics and discharge image test data were obtained.Using ns-level exposure EMICCD to capture the discharge image during the insulator and gap lightning discharge,revealing the physical process and law of discharge more clearly Then the difference in flashover characteristics of the rod-plate gap,the single insulator and the true tower insulator were compared systematically.Finally,based on the actual parameters of the insulators and towers used in the test,a three-dimensional simulation model was established for finite element simulation of the electric field distribution of air gap and insulator under various conditions in Comsol,and the simulation results were compared with the experimental data.The comparison of the simulation results by experimental data partially explained the difference of flashover characteristics.