Study On Methods Of Preventing Ice Disaster Of Transmission Lines By Using Expanded Diameter Conductors

Snow and freezing weather has posed a serious threat to the safe operation of power system,and has a serious impact on industrial and agricultural production and people's lives.Over the past decades,extensive research has been carried out at home and abroad,and dozens of anti-icing and deicing technologies,such as hydrophobic coatings and DC melting,have been proposed.So far,only DC ice melting technology has played a practical role in ice prevention and disaster reduction of power grid.However,there are some limitations in the practical application of DC ice-melting device and DC ice-melting technology in power grid,such as power outage,long ice-melting time,operation icing,high human cost,expensive equipment,huge area,and other shortcomings,and the current technical conditions can not be applied to UHV transmission line ice-melting.Therefore,the development and research of new methods to prevent the occurrence of ice and snow disasters on transmission lines has always been the focus of research at home and abroad.Based on the long-term observation and research of Xuefengshan Natural Ice Coating(Pollution)Test Base of Chongqing University and Chongqing Energy Equipment Safety Field Scientific Observation and Research Station,according to the formation mechanism of transmission line icing in natural environment,this paper puts forward the research of using expanded conductor instead of bundle conductor to prevent ice and snow disaster,so as to reduce the amount of transmission line icing.Thus,the objective of passive and non-manual intervention for ice prevention and disaster reduction is achieved.The main contents of this paper are as follows:(1)Four split conductors can be equivalent to a single conductor in terms of electromagnetic characteristics.For the analysis of the electromagnetic characteristics of four-split conductors,the electromagnetic parameters such as ground capacitance,ground inductance,wave impedance,natural power and the charge carried by a single conductor are mainly selected for analysis.According to the principle that the equivalent radius remains unchanged,the outer diameter of three-splitting,two-splitting and single enlarged conductor is calculated.According to the principle of unchanged transmission area,that is to say,to ensure the current density unchanged,the inner diameters of expanded conductors with different splitting forms are determined.(2)The larger the diameter of the conductor,the lower the collision rate.When the diameter of conductor is larger than the critical diameter of icing,the impact rate is very low and tends to zero,it can be considered that there is no icing at this time.After icing,the diameter of conductor increases gradually and the growth of icing slowly,and the growth of icing is closely related to environmental parameters.(3)The shielding area produced by the windward conductor in the split conductor has an effect on the windward conductor.The windward conductor is in the shielding area,and the collision rate of the windward conductor is lower than that of the windward conductor.At the later stage of icing,the thickness of subconductor icing gradually tends to be the same.(4)Through the experiment of multi-functional artificial climate chamber and natural ice-covered foundation in Xuefengshan,it can be seen that,compared with the split conductor,the percentage of icing reduction of three-splitting,two-splitting and single-expanding conductors increases in turn.The bigger the diameter of conductor,the fewer the splitting roots,and the more significant the effect of icing reduction.(5)Wind loads on four-split enlarged conductor,Three-Split enlarged conductor,two-split enlarged conductor and single enlarged conductor when conductor is iced.The specific load of dead weight,ice weight,vertical total specific load,wind-pressure specific load,ice-free comprehensive specific load,ice-covered wind-pressure specific load and comprehensive ice-covered specific load are also studied.Calculate the breaking force of a single conductor.The vibration of overhead conductor is analyzed.(6)The number of split conductors is large,and the number of expanded conductors significantly reduces.It greatly improves the ice resistance of transmission lines.In severe ice-covered areas,the use of expanded conductors instead of split conductors can reduce the amount of conductor icing,thus preventing transmission lines from ice disaster and avoiding the use of time-consuming and laborious manual intervention,which has significant economic benefits.