Experimental Study on Insulation Coordination of Arcing Horns on HVDC Electrode Lines

Summary

In this paper, the insulation coordination of arcing horns on the electrode lines of a 5000 MW, ±800 kV HVDC system have been analysed. Experiments have been carried out to study the arc extinction characteristic of arcing horns. The discharge gap length of the arcing horns is from 400 mm to 1500 mm. A pulse-wave generator is chosen as the power supply. The maximum output pulse width is 70 ms, and the peak current is 2500 A. In order to investigate the fault clearing efficiency of the arcing horns, dynamic U-I characteristic method is introduced. The influences of line parameters and arc elongation are analysed in detail as well. The results indicate that the arcing horns have limited fault clearing efficiency, especially on long distance and high capacity HVDC electrode lines. The fault clearing efficiency improves significantly with the decrease of the line resistance, but slightly with the increase of the tower footing resistance. By increasing the bundle number of conductors or the conductor number of the electrode lines, the line resistance is reduced and a better fault clearing efficiency is achieved. On the other hand, due to the effect of magnetic and thermal buoyancy forces, the actual length of the arc is much longer than the discharge gap length. Hence, the effect of arc elongation should be taken into consideration. That means the practical performance of the arcing horns is more optimistic.

Additional informations

Authors

Dohnal Dieter, Späth Matthias, Krämer Axel, Zoko Ble Frank, Lehtonen Matti