Analysis And Research On Lightning Protection Of ±800KV Power Transmission Lines

The task of UHVDC transmission is to transmit electric energy in large capacity and far away,which has an unusual position in the power grid.However,the terrain and geomorphology environment through which the line passes is worse,and it is very vulnerable to lightning damage.In summary,it is necessary to study thecomprehensive lightning resistance performance of(±800 k V)UHVDC line.This paper mainly outlines the development of HVDC transmission,the principle of lightning over voltage and the development of lightning protection technology at home and abroad.After analyzing the theory and method of lightning protection calculation of HVDC transmission lines,a simulation model of lightning protection performance of(±800 k V)UHVDC lines is built by PSCAD software.Based on the improved EGM,the calculation model of shielding failure is constructed,and the effects of operating voltage and wind speed on the model are considered.The simulation calculation model can be used to simulate and analyze the lightning resistance of transmission line.From the final data,it can be concluded that ± 800 k V UHV Lugu DC line has excellent lightning resistance level,lightning shielding is an important cause of line flashover,and the polar line voltage and wind speed have an important influence on the calculation results.Careful attention should be paid to the calculation process.Considering that the insulation level,grounding resistance and the height of pole and tower will have different effects on the lightning resistance level of transmission lines.An effective measure to improve the lightning resistance level is to reduce the grounding resistance of poles and towers.Ground inclination,conductor height and protection angle all have important effects on the lightning resistance performance of transmission lines.It is suggested that transmission lines should adopt negative protection angle,and lightning protection measures should be added as appropriate in view of the situation of large ground inclination and high tower pitch.Finally,the reasons for the high lightning flashover rate of transmission lines are analyzedin China,including an increasing number of thunderstorm days,human factors and inadequate line protection measures,and the lightning protection schemes and improvement measures are put forward in view of the above problems.