Mountain Transmission Line Egm Around The Strike Rate

To adapt the need of power load for the quick development of economy, the development of power system is turning for the higher voltage and larger capacitydirection. For just a few years, the 500AC power transmit system breakdown accidents caused by lightning often occurred in our country and others, the research on ultra-high-voltage power transmitting line lightning protection performance also have been paid attention in the worldwide range, but the reports on research deeply and systemically on the subject are of scarce. The design of lightning preventing by existing model is not in accord with the running results for ultra-high voltage transmission line. So it is important significance and applied value for 500kV transmission line lightning protection performance designing by exploring a new model of lightning shielding failure that be the same with lightning protection performance of ultra-high voltage transmission line and analyzing the lightning protection performance of 500kV double circuit transmission line.By studying deeply the lightning protection performance for ultra-high voltage transmission line, the main contents of the paper include:On considering the ascending forerunner effects on the lighting and the back-head lighting cases, the variable step-length method should be applied to the model of the descending lighting forerunner, firstly putting forward the lightning simulation model that adapt to ultra-high voltage transmission line. The calculating on the example and the simulation testing show that the simulation model can reflect the basis rule of lightning striking transmission line and accord with the running experience. The model can be applied to the evaluation and calculating on characteristics of lightning striking the high altitude transmission lines.Through analyzing deeply the lighting protection performance of back striking for 500kV double circuit transmission line, the distributed parameter model of tower is built when analyzing the back stroking lightning protection performance for 500kV double circuit line and applied the statistical method to analyzing the lightningprotection performance of back stroke with considering the randomness of working voltage's phase when lightning stroked the top tower. Aiming at the view of that those nations, such as USA, Japan and Europe: the means of unbalanced insulation can not be applied to doubleThrough analyzing deeply the circuit transmission lighting protection performance of shielding failure for 500kV double line, the EGM is of angle of the lightning incidence. The calculation result is compared simulation model, improved by considering the effect and analyzed by EGM with the circuit transmission line, the author concludes that unbalanced high insulation can sharply decrease the simultaneity rate of lightning back striking as well as not increasing the rate of the single line' breakdown by theory and simulator analysis.After the systematic research of factors that influence the lightning protection performance of shielding failure on 500kV double circuit transmission line, a good advice had also been put forward for the considerable and effective means of lightning shield protection. These factors are angle of the lightning incidence, the height of tower, leaning angle of ground, insulation manner, surge impedance of tower, the array style of conductor and so on.This paper calculates and analyzes the lightning Shielding Failure of SOOkV line and transmission line models developed by EGM. Because of the factor of angle of the lightning incidence, the paper proposes a new method for calculating the rate of Shielding Failure.The calculated result is compared with the measured results and both results are consistent. And it show the shielding failure rate is a function of angle of the lightning incidence> strokes lightning amplitude and ground angle.The EGM is improved by considering the efect of angle of the lightning incidence. It will help designers in making the correct economic judgment.