Abstract
With the increase of both voltage level and the transmission capacity, more attention has been paid to the external insulation of transmission lines. As the main external insulation medium of transmission line, the air gap’s dielectric strength will change when there are floating conductors. In this paper, we established an experiment platform to study the effects of floating conductors, simulated by floating rod electrode, on breakdown voltage, breakdown time, electric field distribution and discharge physical process of long air gaps under lightning impulse. The results showed that the intervention of floating electrode reduced the breakdown voltage and breakdown time of long air gaps, and the position with the longest breakdown time was the same as the position with the lowest breakdown voltage. In addition, the intervention of floating electrode improved the spatial electric field and complexity of discharge physical process.
Highlights
A transmission line is the traffic artery of a power system and the carrier of power energy
Wang carried out actual-scale tests on transmission line towers with voltage levels of 500,20 750,21 and 1000 kV,22 obtained a large amount of breakdown voltage data of the combined air gap under a positive switching impulse, and found that there is a scitation.org/journal/adv lowest breakdown voltage position in combined air gaps with a floating conductor
After building up the above experimental platform, we first carried out 1.2/50 μs positive lightning impulse tests without a floating conductor to verify the effectiveness of the test
Summary
A transmission line is the traffic artery of a power system and the carrier of power energy. The air gap in the tower is the dielectric of transmission lines. Many researchers have studied the breakdown characteristics of the air gap in the tower.. Wang carried out actual-scale tests on transmission line towers with voltage levels of 500,20 750,21 and 1000 kV, obtained a large amount of breakdown voltage data of the combined air gap under a positive switching impulse, and found that there is a lowest breakdown voltage position in combined air gaps with a floating conductor. The breakdown voltage of the combined gaps was calculated through the coupled streamer leader development and transformation process, and the accuracy of the model was verified based on the above-mentioned test data. Gao et al. built the vertical combined gap model and photographed the different physical processes by using a high-speed camera, which improved the relevant research
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