Study On Dynamic Response Of Non-uniform Ice-shedding Of Transmission Lines

Severe ice and non-uniform ice-shedding vibration of transmission lines are the main factors causing mechanical and electrical accidents,which seriously threaten the safe operation of transmission lines.Therefore,studying the ice-shedding vibration of transmission lines has important guiding significance for power grid construction and deicing technology.In this paper,aiming at the dynamic response problem of non-uniform ice-shedding of multi-span transmission lines,firstly,the continuous two-span training lines are used as the test model,and the suspension concentrated mass block method is used to simulate the ice shedding test.The parameters such as ice-shedding thickness and ice-shedding amount in ice-shedding during the same period are analyzed,and the effects of icing thickness,de-icing mode and de-icing speed on the change of conductor displacement and tension are discussed in the zipper de-icing test.Secondly,the simulation model is established by ABAQUS finite element software,and the selection basis of element type of model components,the shapefinding method of conductor and the simulation method of icing line de-icing are introduced respectively.The validity of the model and parameters is verified by comparing the test data of relevant working conditions.The simulation model is used to further study the ice thickness of adjacent sections and the local de-icing mode of single section during the same de-icing process.Finally,based on the large span model,the effects of de-icing position,deicing speed and de-icing mode on the jump height and tension of wire are studied.The main research results are as follows :（1）During the same period of ice-shedding,the maximum jump height of ice-shedding conductor and the change of midpoint stress of conductor increase with the increase of iceshedding thickness and ice-shedding amount;when the partial ice-shedding of a single gear is carried out,the symmetrical de-icing method from both sides should be adopted,and the ice-shedding amount should be controlled below 50% at the first partial de-icing.（2）The increase of ice-shedding speed will aggravate the vibration effect of the wire.The single-stage zipper de-icing method has little effect on the vibration characteristics of the ice-shedding.Sequential unzipping ice-shedding is the most dangerous de-icing condition in two consecutive de-icing modes..（3）Whether the non-deicing gear is iced or not has little difference on the jump height caused by single-stage unzipping ice-shedding.In the case of different gear de-icing,the jump height of intermediate gear de-icing is increased by about 20% compared with that of adjacent gear de-icing.When the speed of unzipping ice-shedding is less than 20m/s,it is similar to the way of static unloading.When the speed is greater than 200m/s,it is basically the same as the synchronous ice-shedding.The maximum displacement and midpoint tension of conductor increase with the increase of ice-shedding speed.（4）Under continuous three-span ice-shedding mode,sequential unzipping ice-shedding is the most unfavorable de-icing mode,and the vibration effect caused by simultaneous three-span de-icing is the smallest.Continuous three-stage zipper de-icing,different de-icing speed will produce large displacement amplitude in the middle gear,and the maximum deicing speed is 100 m/s.