Numerical Simulation Study On Dynamic Responses Of Transmission Lines With Lager Span And High Elevation After Ice-shedding

When the ice on the conductor of transmission line falls off in ice area,it will cause the vibration of the conductor,which will impact the conductor and tower,and even lead to the occurrence of electrical insulation accident or mechanical accident,which will affect the normal operation of transmission line.In Sichuan,Guizhou,Chongqing,Hubei and other provinces,there are many transmission lines across mountains,canyons and rivers.These lines usually have the characteristics of large span and high elevation difference.The jump height and tower safety of large span and high elevation difference line during ice-shedding may be different from that of conventional line,which deserves further systematic study.Firstly,this paper describes the numerical simulation method of dynamic response of transmission line ice-shedding,including the establishment of finite element model of conductor,spacer and insulator string,the numerical simulation method of conductor ice-shedding process and its implementation in ABAQUS finite element software,and validates the correctness of the method by an example.Aiming at the problem that the existing formulas for calculating ice-shedding jump height of conductors are not suitable for large span and high elevation difference lines,based on the existing research results,the dynamic response of conductors under different line structure parameters and ice-shedding conditions is simulated by finite element method,and the ice jump height of conductors and its pre-and post-ice-shedding sag obtained by numerical simulation are analyzed.Based on the data relations of sag,span and elevation difference,a simplified formula for ice-shedding jump height of conductor considering the influence of line span and elevation difference is obtained by using non-linear regression method.The formula is suitable for lines with large span and elevation difference,and improves the application scope of the formula.When the conductor is subjected to wind load,besides the vibration of the conductor,it will oscillate horizontally,and its trajectory is approximately elliptical.The transverse swing caused by ice-shedding of conductors under wind load is also an important parameter affecting the insulation safety of conductors.In this paper,a simplified formula for calculating the transverse swing of conductor is given based on the dynamic response of conductor ice-shedding in wind.A finite element model of tower-line coupling system for typical large span and high elevation difference transmission lines is established.The stress and deformation of tower-line system are calculated and analyzed when conductors are iced.The dynamic response of tower-line system under the worst conductor ice-sheeding is numerically modeled.The stress distribution of conductors and tower during iced and ice-shedding is obtained.The stress and strength of tower,conductor and ground wire are analyzed.The research results of this paper provide an important basis for the design of large span and high elevation difference lines in ice area.