Tower Air-gaps discharge characteristics and insulation coordination for UHV AC double-circuit line

• Main Authors: Huo Feng, Nan Jing, Ye Qiming, Ma Yeming
• Format: Article
• Language: English
• Published: Wiley 2019-04-01
• Series: The Journal of Engineering
• Subjects: power transmission lines; poles and towers; insulators; lightning protection; air gaps; electrodes; overvoltage protection; power transmission protection; distance 7.2 m; distance 6.7 m; distance 6.5 m; distance 2.9 m; time 1000.0 mus; discharge voltage gradient; UHV AC double-circuit tower; lightning impulse; wavefront switching impulse voltage; inverse V-string; tower air-gap discharge characteristics; lightning protection air-gap configurations; phase air-gap configurations; double-circuit UHV AC power transmission line system; tower frame discharge testing; insulation coordination; power frequency voltage; discharge characteristics curves; high-voltage electrode; inverse V-type insulator tower air-gaps configuration; UHV AC double-circuit line
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8720

In order to give out inverse V-type insulator tower air-gaps configuration of double-circuit UHV AC power transmission line, different distance air-gaps from high-voltage electrode to tower frame discharge tests of inverse V-string are carried out. Discharge characteristics curves of power frequency voltage, 1000 μs long wave-front switching impulse voltage, and lightning impulse of UHV AC double-circuit tower are obtained. Results show that the 50% discharge voltage gradient of bottom phase air-gaps is higher than middle phase. 1000 μs wave-front switching impulse 50% discharge voltage gradient of bottom phase air-gaps is 4.6% higher than the middle phase. Based on the test results and the characters of operating voltage and overvoltage of UHV AC power transmission system, the UHV AC double-circuit tower inverse V-type insulator air-gaps configuration is proposed. The air-gap configurations of power frequency voltage and switching overvoltage are 2.9 and 6.5 m, and the lightning protection air-gaps are 6.7 and 7.2 m, in mountains and plains.