Research On Icing Laws For Hunan Ultra High Voltage Transmission Lines And Optimal Solution For Icing Disposal Equipments

Under extreme weather conditions, transmission line icing can easily result in towercollapses, broken strands and even large scale blackout accidents, which have brought a greatharm to the safe and stable operation of the power grid. Researchers and scholars both athome and abroad has analyzed the icing mechanism of transmission lines, the whole processof icing, and various covered ice parameters and their interactions. Now the related researchhas achieved some initial results, but most of the achievement is qualitative analysis andthere’s no quantitative evaluation. So this paper is aimed to fill the vacancy and study theicing law of ultra high voltage (UHV) transmission lines in Hunan Province.Based on the thorough analysis results of the existing meteorological data and icedrecords, the related causing factors of the2008repeated icing events are discussed thatcombined with Geographical environment and climate characteristics. The principle that theareas with relative high frequency of freezing disaster occurrence and the areas with relativelow frequency are arranged as saw-toothed, which is consistent with the strike of mountainsand extend towards the northeast, are disclosed in this paper. The analysis results show thatthe long time cryogenic freezing rain and snow disaster is caused mainly by the stableatmospheric circulation; the stable strong disturbance on the south branch of zonal frontalzone is the primary cause of blizzard; the formation and growth process of freezing iscombined result of various meteorological elements. Then history glaze cases of the threeUHV transmission lines in Hunan are analyzed. The number of continuous glaze days overnext20years is predicted through the GM model constructed by this paper. The focus icingsection along the UHV transmission lines are summed up.Based on the time difference of traveling wave propagation, a new icing thicknessmeasuring method is proposed. The projects verification results show that this method canexactly reflects the icing thickness on site. Both the space transient electromagnetic sensorsand the traveling wave detecting theory are also designed by this paper. By the non-contactsensor mounted on the transmission line towers, the practical application of the above icingthickness measuring method can be realized.Finally, based on the TOPSIS algorithm and the microtopography influence ontransmission line icing accumulative process, optimal configuration of the icing monitoringsystems and ice-melting devices along the three UHV transmission lines are carried out. Thescheme designed by this paper can achieve the maximum effective range icing monitoring ofthe UHV transmission line and melt ice with the maximum efficiency. According to the differentiation of UHV transmission lines, this paper provides relatedsolutions, which also have an important guiding significance for engineering and areconfirmed by Hunan Electric Power Company. The proposed optimal configuration scheme ofthe icing monitoring systems and ice-melting devices are expected to be applied in the HunanUHV transmission line.