Energized Icing Accretion and Ice-melting Testing Technologies at Xiaoshajiang Natural Disasters Test Site in Xuefeng Mountain

摘要

At the year of 2011-2012,a Xiaoshajiang natural disasters test site has been built in Xuefeng Mountain in Hunan province,china,for researching energized icing accretion and ice-melting testing technologies of transmission conductor under real natural environment.The test site,with the altitude of 1385m and more than 60 perennial icing days,has the micro-topography and micro-meteorological features of high intensity ultraviolet,foggy.The test site owns an 800m long 500kV transmission line with fully insulated design between sub-conductors,DC ice-melting devices,icing equipment that can output high voltage of 400kV and heavy current of 1500A at the same time.icing accretion with running voltage and current and ice-melting tests of transmission conductors have been carried out under different meteorological conditions.Through hanging various types of insulators on the 18m×22m×25m ice observation frame,icing accretion of insulators have been established.Some conclusions are drawn from the experiments in five winters: natural meteorological parameters are uncontrollable and irregularly variable.When electric field around the test samples is low,icing thickness grows with the increase of voltage due to polarization and energization of water drops;when electric field gradually increases,the growth of icing thickness can be restrained by joule heat arising from corona current and collision between ions and water molecules around the test samples.Also,density of ice layer decreases as the increase of voltage.Simultaneously,the growth speed of ice-coating will be slowed down through decreasing freezing coefficient of water droplets on test conductors because of Joule heat produced by running current,the test insulators' surface with stronger hydrophobicity will make icicles grown more easily.In the ice-melting process,the larger the icing eccentricity is and the thinner the icing thickness on the upper surface of conductor is,the shorter the time for ice-melting will be.