| Lightning stroke is the main reason of transmission line trip.The new mechanism and measures of lightning protection is a hot and difficult research at home and abroad.Lightning rod is widely used in the lightning protection of transmission lines,however,in order to continue to reduce lightning accidents of transmission lines,various new lightning protection device including the semiconductor lightning rod,the impedance lightning rod,the optimized lightning rod and the inductive lighting rod are put forward.This paper is focus on the inductive lightning rod that aimed at reducing lightning current steepness and amplitude so as to improving the lighting protection performance of back-flashover.The finite element analysis,electromagnetic transient analysis,amplitude frequency response analysis and small signal test of the sample are all carried out to find out the mechanism and evaluate the lightning protection effect.At first,the chain equivalent circuit of the inductive lightning rod has been built and based on the finite element analysis the distributed parameters and their influence have been studied.Secondly,the dispersion of lightning current during its propagation in the inductive lightning rod and the influential factors of the propagation has been studied.Based on the spectrum analysis of lightning current,the theory that the inductive lightning rod works on the lightning current by filtering is put forward combined with the chain equivalent circuit of the inductive lightning rod.Next,based on the PSCAD/EMTDC electromagnet transient analysis the influence of the chain equivalent circuit parameters L0 and C0 is studied,as well as the influence of lightning current filtering on the lightning protection performance of transmission lines,and the lightning current filtering effect is also further analyzed by the electronic simulation software Multisim.On this basis,a 220 kV transmission line is established to analyze the influence of the installation of the inductive lightning rod on the tower with different parameters,and then verify its lightning back-flashover level.In addition,with the combination of the amplitude frequency response analysis,electromagnet transient analysis and spectrum analysis of the chain equivalent circuit,the mechanism of the inductive lightning rod is further explained from the aspect of time domain and frequency domain.Last but not least,designed the sample of the inductive lightning rod,and the influence of the inductive lightning rod on the lightning current and it frequency range is verified by small signal test.Moreover,analyzed on the overvoltage distribution and electromagnetic field with practice,and the limiting conditions for the realization of actual sample are put forward. |
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