Numerical Simulation Of Vibration Of UHV Eight Bundled Conductors Under Wind Loads

According to the UHV development plan issued by the national Power Grid Corp,by 2020,the UHV power grid will form a strong power grid with the core of North China,central China and East China,connecting China’s large regional power grids,large coal bases,large hydropower bases and major load centers.The Nanyang Jingmen 1000 k V AC UHV transmission line has been built in the two provinces of Henan and Hubei.The transmission lines of the Jiaba Shanghai and Jinping Soviet high voltage transmission lines pass through Hubei,Hunan and Anhui,and the 1000 k V UHV AC lines generally use eight split conductors.The multiple split number of the eight bundle conductor leads reduces the power loss of the line,and realizes the long distance transmission of electricity,but it will also cause the aerodynamic parameters of the line to become more complex.The vibration form of the wire will be more complex under the wind load,and the line safety is seriously threatened.The circuit transmission charges of UHV transmission lines are large.If there is a safety accident on the line,it will have a serious impact on the national economy.At present,the research on the wind induced vibration of the transmission line is relatively lack,especially the wind induced vibration of the UHV eight split wire is an urgent problem to be solved in the design and safe operation of transmission lines.First,the aerodynamic coefficients of eight bundled conductors are measured by wind tunnel test.The experimental model was designed and made.The curves of the lift coefficient,drag coefficient and torque coefficient of each sub conductor of eight bundle conductors under the typical wind speed were obtained with the variation of the wind angle of attack.The test results show that the lift coefficient and the drag coefficient of the leeward traverse are obviously influenced by the wake of the windward traverse,while the torque coefficient is less affected.In the wind speed range of the test,the wind speed has little effect on the lifting coefficient and the drag coefficient of the eight split lead wire,and there is little shadow on the torque coefficient.The larger the ice thickness is,the greater the drag coefficient and torque coefficient of the sub-conductor is,and the lift coefficient is more variable with the wind attack angle.Secondly,in order to analyze the influence of different turbulence on the aerodynamic coefficient of eight bundle conductors,the aerodynamic coefficients of eight bundle conductors under different turbulence levels were tested in the wind tunnel test.The experimental results show that,compared with the aerodynamic characteristics of the crescent-shaped eight bundle conductor under the action of turbulent flow and uniform flow,the lift and torque coefficient of some sub wires under the action of turbulence increase partly.Besides,the different angles of wind attack will lead to a significant difference in the influence of turbulence on the aerodynamic coefficients of each sub conductor.It is known from the wind tunnel test that there are many disturbing currents in the windward side sublines under the multi splitting lines under the wind load,and the aerodynamic coefficients of each sub conductor in the wind field will be different.In addition,the multi splitting sub-span oscillation phenomenon under wind load are also more prone to lead.This phenomenon is a special phenomenon of multiple splitting lines,which will lead to the phenomenon of "whiplash",and even lead to fatigue damage of wires,wire clips and spacers.If the line transmission power is large,if the line fails,it will cause serious harm to the national economy.Secondly,the iced multi splitting line is easily induced by the excitation of wind load.The phenomenon is due to the eccentric instability caused by the non-circular section when the conductor section is covered by ice under wind load.Line galloping has the characteristics of low frequency and large amplitude,so it often causes the phenomenon of flashover and tripping and so on.When it is serious,it will also break the line.Besides,due to the influence of surface roughness,the closer the ground is,the more unstable the wind is,and the higher the turbulence is.The galloping of iced conductor will be more complicated under the action of high turbulence.At present,there is a lack of specific research on UHV transmission lines under wind load.In order to explore the vibration mechanism of UHV transmission line under wind load.In this paper,based on the aerodynamic parameters measured by the wind tunnel test,the subgrade vibration of the eight bundle conductor is studied based on the finite element software.Secondly,the dance mechanism of the eight bundle conductors is deeply explored.Finally,in order to obtain the influence of the turbulence on the aerodynamic coefficients of the sub conductors,the effect of the turbulence on the aerodynamic coefficients of the sub conductors is obtained.The wind tunnel test is carried out on the moon shaped iced eight bundled conductor.Based on that,the nonlinear finite element method is applied to analyze the turbulent problem of iced eight bundled conductor,and the variation rule of galloping amplitude with turbulence is obtained.The research results in this paper are of great significance for the wind-induced vibration of eight bundled conductors and the follow-up research of prevention and control technology.