Wind-induced Response Simulation Of Transmission Tower-line System Under Complex Terrain Condition

As important load-bearing facilities of transmission lines,the reliability of transmission tower-line system is directly related to the safety of electric power system.Tower-line system made up of lattice towers and transmission line is lightweight and flexible-high,so it is sensitive to wind load.With the increasing scale of transmission lines,high towers and long span lines become the development tendency,and greater emphasis should be given on the wind resistance of tower-line system in practical projects,so researching wind-induced response characteristic of tower-line system is important to ensure the safety of electric power system.At present,most of tower-line system wind-induced response research simplified wind load model,and ignored the influence of surrounding terrain.In practical construction design,the consideration about the effect of surrounding terrain is simplified according to the standard parameters,and there is no adequate study on the worst wind direction of wind-induced response.With a transmission line in mountainous terrain of Wenzhou as the engineering background,numerical simulation study was conducted based on CFD and FEM from the following aspects in this thesis:Firstly,numerical simulation of wind field around the transmission lines was conducted.Based on the elevation data of surrounding terrain,wind field computational domain was constructed,and the three-dimensional near-ground wind field CFD simulation was conducted.The results show that mountainous terrain has significant acceleration effects on local wind field,and some of wind profile results are different from the exponential distribution model in the standard,so exponential distribution model in the standard cannot describe wind field characteristics of the transmission lines under complex terrain condition.Secondly,the wind-induced response analysis of tower line system was conducted by coupling CFD simulation results.Based on the parameters from practical project,the two towers and three spans of lines model was constructed,then wind-induced response analysis of tower-line system under complex terrain conditions was carried out by coupling wind field CFD simulation results.It is found that longitudinal direction load caused by tension difference of lines has significant effect on the response of tower,so the difference between spans in strong wind area should be controlled in actual engineering design.By comparing with the calculation results according to the standard parameters,it was found that the simplified calculation method according to the standard parameter overestimated the longitudinal direction load of tower,principle member shear response and the dynamic response,among which principle member shear calculation deviation was 15.89%,and the relative deviation of the difference between leeward side principle members axial force is 34.09%,Therefore,terrain correction coefficient should not be applied to simplify the analysis of wind-induced response of the tower-line system under complex terrain condition.Thirdly,the effect of tower-line coupling,span length,traverse angle and complex terrain on the worst wind direction of tower body response was explored.The windinduced response simulation of transmission tower without line,different span length and traverse angle tower-line systems under different wind direction was conducted.It found that tower-line coupling effect and long span makes the worst wind direction close to transverse line direction,and traverse angle makes the worst wind direction close to the bisector of exterior angle between lines.Finally,wind-induced response analysis of tower-line system under different wind directions was conducted by using CFD wind field simulation results,and it was found that the effect of actual terrain on the worst direction of wind-induced responses should not be ignored.