Research On Lightning Protection Of1000kV AC Transmission Lines

A lot of high-voltage and EHV transmission lines operating experience have shown that:the lighnting is the main reason to cause the trip faults of transmission lines at home andabroad.And with the gradual improvement of voltage levels, lightning proportion willgradually increase.Compared to the high-voltage and EHV transmission lines, UHV ACtransmission lines have those own characteristics,such as: the higher voltage level,the morecomplex parameters,the farther transport,the higher tower,the bigger attracting lightningarea and more vulnerable to be lightning stroke etc. It is well known that lighning activity isvery strong in China.1000kV UHV AC transmission lines are located in the wilderness andwind in the mountainous.Most of lines corridor get through the complex environment regionsand face a severe test of ice, filth and lightning.Therefore,there is important significance tomake reaserch and design of lightning protection and ensure safe and reliable operation of1000kV AC transimission lines basded on the valuable experience.Focusing on those own characters and the current problems of lightning protection ofUHV transimission lines,the lightning protection of1000kV AC transimission lines areresearched in this paper.the main work and innovation points are expressed as follow:1. In order to more accuratlly simulate the wave process of lightning striking groundwires and conductors, the corresponding component models are created by ATP-EMTP,suchas: the tower model,the line model,insulator flash model,resistance model etc..2. The strong impulsive corona is produced when high amplitude lightning current stikesground wires and conductors.Focusing on the shortage of only considering impulsive coronaof the conductors and the characteristics of1000kV UHV AC transmission lines, andaccording to the q-u characteristics of corona, the equivalent circuit models of corona of thecorresponding transmission lines are established and combined with Jmarti lines byATP-EMTP. Back striking and shielding failure lightning withstand level for1000kVUHVAC transmission line are respectively analyzed.3. Based on the impact of line arrester on lightning protection of high-voltage and EHVtransmission lines, the effect of line arrester installation mode、the frequency voltage and thegrounding resistance on back striking and shielding failure lightning withstand level areanalyzed. The results show that: line arrester can significantly increase lightning withstandlevel for1000kV AC transmission line and reduce lightning trip-out accidents.4. Based on the past electrical geometry model(EGM),the terrain,wind and powerfrequency voltage are considered.The trip-out rate of shielding failure of1000kV AC transmission lines is calculated by improved EGM.It makes analysis more accurate andactual.