The Research On The Lightning Protection Performance Of Double Circuit For 500kV Transmission Line

Electricity production is the key to national economic development, With the increasing of scale and transmission capacity, while the available overhead transmission line corridors become increasingly strained. The technology of double-circuit on single towe has become an inevitable trend in the development of EHV backbone grid. Japan, the United States and other countries EHV grid the same double-circuit transmission tower is relatively common,In china, Jian Zhe and Three Gorges Power Station have also built a number of 500kV EHV transmission line tower double,. Because of 500kV Double-Circuit Transmission Lines’Tower increased, Lead thunder area increases and make the lightning trip-out rate to rise, has a condition of the insulator double flashover trip at the same time, Seriously affect the stable operation of power system. So lightning protection performance analysis for common-tower double-circuit transmission lines has important engineering practice.This Thesis based on the ATP-EMTP for lightning performance calculation and analysis of back flashover for 500kV AC transmission lines with double-circuit on sin-gle tower,consider more near scene actual of multi-wave impedance Tower model, Using in frequency domain with rational function approximate processing A(ω) and Zc J.Marti line model, while with nonlinear inductance model instead of single value inductance for pilot Flash complex model of simulation research, Considered the precursor of current while avoiding the parameters precomputation. Improve the precision of calculations, using statistical method calculation analysis the influence of kinds of factors on the counterattack resistance lightning level and tripping rate. Study on the EGM, Analysis and calculation the trip around strike rate of 500kV Double Circuit Transmission Line, Analysis various factors on the trip rate, and introduced the basic concept of differentiation of mine, on the basis of an extensive collection and research, reform measures proposed mine site in line with the practice.Results showed that as the impulse grounding resistance decreases, tower height reduced, Line back striking rate was reduced trip,and power frequency voltage has a lot of influence onLightning withstand level of line, should be taken into account. With striking distance factor, Fengbai angle, tilt and lightning ground wire protection angle increases, the shielding failure rate of 500kV Double Circuit Transmission increased significantly. Analysis calculated for a typical tower:When under the action of lightning overvoltage, the action of the wind speed reaches 26.8 m/s, it could lead line trip, this calculated value for engineering reference.