| With the rapid development of social economy,the long-distance transmission of electric energy has become an indispensable part of people's daily life and production.High voltage overhead transmission is the main way of long-distance transmission of electric energy,which may be affected by wind load,rain and snow load and earthquake during its working period.Compared with the earthquake load,the rain and snow load and wind load are more frequent,especially when the transmission line becomes a non-circular section due to icing,under certain wind speed conditions,the conductor will produce a low-frequency,large amplitude self-excited vibration,also known as galloping.Since the 1930 s,the research on this problem has never been interrupted,but it has not been solved reasonably yet.The line damage accidents caused by galloping,such as inter phase flashover,tripping and power failure,broken strand of conductor(ground),damage of hardware and insulator,loosening and falling off of tower bolts,even broken line and tower toppling,still occur frequently,which seriously affects the production and life of the people.Therefore,it is necessary to study the aerodynamic characteristics of iced transmission lines and the wind-induced vibration response of iced transmission lines.In this paper,based on the background of a 500 k V high-voltage transmission line project,the wind-induced vibration response characteristics of iced transmission tower-line system are studied on the basis of the study of crescent-shaped iced single transmission line and crescent-shaped iced multi-split transmission line.The main contents and conclusions are as follows:(1)Taking single conductor and quadruple bundle transmission line as examples,the aerodynamic characteristics of conductor under different wind attack angle,different wind speed and different ice thickness are analyzed.The research shows that the wind attack angle range of transmission line prone to vertical galloping is 46.3°-76.4°and 131.3°-173.5°,and the wind attack angle range of transmission line prone to torsional galloping is 131°-180°.Therefore,the actual transmission line should bebuilt to avoid the wind attack angle range.(2)The obtained aerodynamic force is transformed into horizontal force,vertical force and torsional force on the ice covered transmission line through the angle relationship,and the wind-induced vibration response of the transmission line and the transmission line in the tower line system with two fixed ends is analyzed.The results show that the displacement response of the transmission line in the tower line system under the action of wind load is far greater than that of the transmission line with two fixed ends.It shows that the transmission tower has a certain amplification effect on the wind-induced vibration response of the transmission line.(3)Taking the case of 400 m span,10 mm ice thickness and 60 ° wind attack angle as an example,the wind-induced vibration response analysis of the ice covered transmission tower line system under different wind speeds is carried out.The results show that the starting wind speed of the transmission line in the project is 4.788m/s.Therefore,when the wind speed is greater than 4.788m/s,attention should be paid to monitoring and anti galloping measures should be taken.(4)With the increase of wind speed,the displacement and stress response of the transmission tower increase to a certain extent,and the increase is faster.The maximum displacement occurs at the top of the tower,and the maximum stress occurs at the leg and cross arm of the tower,which belongs to the more dangerous part.In practice,special attention should be paid. |
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