Research On Dc Arc Extinguishing Characteristics Of Arcing Horn

This paper mainly studies the effect of different factors on DC arc characteristics, the installation way of arcing horn on grounding line and arcing horns and the insulation coordination of arcing horn and DCtransmission system, with the grounding line of Puer Converter station in ±800kVHVDC transmission system from Nuozhadu to Guangdong as the research object.Firstly, Dc arc characteristics and the research status of arcing horn on theory and engineering applications are presented in this paper to determine the main direction of research on the dc arc-extinguishing ability of arcing horn. In addition to electromagnetic force, wind and thermal buoyancy, the arc-extinguishing ability of arcing horn also is relevant to installation way of arcing horn, gap distanceand system capacity.Secondly,combined with the actual transmission line parameters, the arc test platform of arcing horn simulating DC grounding line is established.The effect of different factors has been tested with a high speed camera recording the whole process of arc development.The results show that electromagnetic force significantly effect on the transfer and stretch of electric arc, while wind and thermal buoyancy effect isn’t significant because of limits such as pulse width. Whenthe minimum discharge gap distance is 400 mm, Claw arcing horn stretch arc up to 1400 mm longer than 1200 mm as the others do, which is most beneficial to arc extinguishing.Then,electromagnetic calculation model is set up to analysis the influence of fault location and tower grounding resistance on electromagnetic force and finally suggestionsaboutinstallation way of arcing horn are given. When arcing horn is installed paralleling to transmission line and toward the grounding pole(α=0°),electromagnetic force of arc reaches the maximum value which is most likely to make arc away from insulator string.Electromagnetic force decreases with the fault point location getting closeto the grounding pole and tower resistance increasing.At last, arc volt-ampere characteristic curveobtained through arc test is combined with output characteristic curve of DC transmission system, aiming to determine and increase the protection range of arcing horn.The results show that for the arcing horn of a certain gap distance, the protection range increase along with tower grounding resistance rising. Regardless of the arc stretching, when gap distance is 650 mm and tower resistance is 5 Ω, the protection range is about 5%;While iftower resistance changes to 15Ω, the protection range is about 20%.In addition, increasing the number of grounding lines can increase the protection range of arcing horns.Taking tower grounding resistance for 5Ω, for the arcing horn of 1000 mm, when the number of grounding lineschanges from 2 to6, the protection range increases from 5% to 12% more than 2 times, which is remarkable.