Experimental Research On Critical Current To Prevent Wires From Icing

Because of the climate and terrain,China is one of the countries where ice accretionof conductors is very serious.The United States, Canada, France, Russia, Japan, Korea,etc. are frequently attacked by icing in the world. In addition, with the continuousprogress of the construction of power grids and the emerging of global extremeweather, the Transmission Line Icing problems will become even more prominent. It isa great loss to operational safety and economic of power grids. Therefore, theresearches for mechanism of icing and solutions have good engineering application andsignificant economic and social benefits.Firstly, this paper reviewed the research status of conductor icing at home andabroad, summarized the shortage of the research and proposed the main contents ofthis paper.Secondly, not only the causes and conditions, influencing factors, physicalproperties, theoretical prediction model, the methods of anti-icing and de-icing usingcurrent but also the galloping and prevention of conductor icing are introduced.Thirdly, the paper analyzed factors of wire icing, determined the main factors,studied the heat transfer calculation of wire in units per time and length on icingconditions, established heat transfer model of solid-liquid coupling, solved energyconservation equations connected to meteorological data, geometry parameters ofwires, electrical parameters of wires. And the meteorologicla conditions andcharacteristics of wire icing exist are observed. The characteristics of heat transfer andflow under this condition are analyzed, and then we established the mathematiclamodel of critical current based on these conditions (energy conservation equation ofelectricity wires).Fourthly, according to the experimental results of heat transfer which is fromsupercooled droplets across the wire, Nu correlation is obtained. The research field ofthe air across cylinder in convective heat transfer is expanded, and this complemetedthe new knowledge for the convective heat transfer.Finally, the natural environment of this experiment is prouduced by artificialenvironmental chamber. The specimens are ohmic heated and experimented in the icewind tunnel according to theoretical results of critical current. The variations ofcritical current with wind speed, temperature liquid water content and othermeteorological parameters are obtained. The critical current is calculated throughexperimental study in the icing environmental conditions. Ultimately, we obtained that critical current increased with the wind speed increases and the air temperaturereduces. LWC affects it slightly. Then the model is modified, and we obtain thecorrelation of the critical current.This paper has an important engineering application: provide theoretical supportfor the use of the critical current to prevent icing.