Lightning Protection Calculation And Application Of 10kV Distribution Line Based On ATP-EMTPand CDEGS

With the development of electric power industry in China,the research on transmission lines tends to be mature.However,distribution lines,as user-end overhead lines,have a large range and a wide distribution,which directly affect the user’s electricity use experience.Therefore,the importance of distribution lines is increasing day by day.In the accidents of distribution lines,lightning strike accidents account for a large proportion,in which lightning strike caused by distribution lines short-circuit,broken lines and other tripping accidents have accounted for 50%-70%of the total accidents of distribution lines,so it is very important to correctly understand,evaluate and prevent the impact of lightning on distribution lines.In this paper,the theoretical calculation method of lightning resistance level and tripping rate of distribution lines under different lightning protection configurations is studied.Calculation of lightning resistance level of distribution line includes conventional configuration,single arrestor configuration and lightning arrestor configuration.Lightning tripping-out rate calculation including the neutral point grounding or via arc suppression coil grounding,neutral point via small resistance grounding lightning strike tripping rate and the induction lightning trip-out rate of calculation.In this paper,a conventional single-circuit distribution line is taken as an example to build the ATP-EMTP simulation calculation model of the 23-base distribution tower,and the simulation parameters are configured according to the typical lightning protection design of Guangdong Power Grid distribution network.The over-voltage characteristics of insulators and the over-voltage propagation characteristics of insulators along the lightning shield are calculated,and the lightning resistance level and flashover characteristics of the line were investigated.the rationality and accuracy of the simulation model are proved by comparing with the lightning resistance level verified by the example in chapter 3.At the same time,the influence of grounding resistance and insulation level on lightning resistance level and flashover characteristics of the line is analyzed.This paper also explores the safety distance of the step voltage at the bottom of the distribution tower when lightning strikes the tower.Firstly,the ATP-EMTP simulation software was used to calculate the different soil resistivity and current of the pole tower at the top of the lightning tower.Secondly,CDEGS simulation software is used to convert the time-domain form of lightning flow to the frequency-domain form,and the frequency-domain responses of lightning flow under different frequencies are calculated respectively.Finally,the inverse Fourier transformming is used to transform the frequency-domain response of lightning current into the time-domain form and superimpose the step voltage near the base of the tower.The safety distance near the tower is obtained according to the safety criterion of step voltage,which provides reference for lightning protection design of distribution network.