Single-phase Installation Method Of Parallel Gap In 10kV Overhead Bare-conducting Line

10kV overhead bare-conducting line has dense network,complex structure,less lightning protection measures and high lightning trip rate.Installation of MOA has a significant effect on improving the lightning withstand level of 10 kV overhead bare-conducting line,but a large number of use will cause excessive burden of later operation and maintenance.Installation of parallel gap is an economic and effective ’grooming’ type lightning protection measure.However,the traditional three-phase installation method of parallel gap reduces the lightning withstand level of the line,which limits the application of this method.Based on the interphase short circuit tripping mechanism of 10 kV overhead bare-conducting line,two single-phase installation methods of parallel gap are proposed to improve the lightning withstand level of the line.Firstly,the relationship between 99%discharge voltage of parallel gap and gap distance and 0.1%discharge voltage of P15 insulator are obtained by lightning impulse discharge test.The discharge voltage range of parallel gap is determined based on the principle of probability comparison insulation coordination.The overvoltage protection principle of two single-phase installation methods of parallel gap is studied.The results show that the two single-phase installation methods of parallel gap are feasible to improve the lightning withstand level of the line.Secondly,based on ATP-EMTP software,the simulation calculation model of 10 kV overhead bare wire is established.Under the induced lightning overvoltage,lightning line overvoltage and lightning tower crossarm overvoltage,the influence of two single-phase installation methods of parallel gap on the lightning withstand level of 10 kV overhead bare wire is simulated and calculated.The results show that the lightning withstand level of the 10 kV overhead bare wires can be significantly improved by 101.2%when the single-phase transmission line with parallel gap is installed under the overvoltage of the tower crossarm.When 10 kV overhead bare wires suffer induced lightning overvoltage,the installation method of parallel gap single same line can significantly improve the lightning withstand level of the line,up to 84.9%;When the 10 kV overhead bare conductor line is subjected to lightning tower crossarm overvoltage,the installation method of single same line with parallel clearance has a significant effect on the improvement of lightning withstand level of the line,up to 103.5%.Finally,through the comparative analysis of the simulation calculation,taking the line lightning withstand level and the number of lightning insulator flashover as quantitative indicators,according to the characteristics of 10kV overhead bare wire line lightning fault,this paper puts forward the installation mode selection of parallel gap in 10kV overhead bare wire line and several schemes to determine the distance of parallel gap.These schemes have significant effects in improving the lightning withstand level of the line and protecting the line insulators,and have important practical significance for the safe and stable operation of the 10kV overhead bare-conducting line.