Study On The Wind Field Characteristics Of Mountainous Terrain And Wind-induced Response Of Transmission Tower-line System

China has a vast area,and the mountainous terrain has a large proportion of the country's land area.Natural winds passing through the mountainous terrain will form a complex distribution of wind fields.The unique wind field structure effects of mountainous terrain make the wind-induced effects of transmission tower line systems different from flat areas.At present,the terrain correction factor for regulating the wind speed of houses and transmission lines in China is not yet detailed enough,which may lead to fatigue collapse of the transmission tower line system under the mountain terrain wind field.This paper takes hilly terrain and canyon topography as the research object,studying the topographic wind field characteristics of mountainous regions,and compares the wind-induced effects of cup-shaped transmission tower line system under different topographic wind fields and provides effective methods for vibration reduction based on the wind tunnel test.The main research work of the paper and achievement are as follows:(1)This paper reviews the research status on the characteristics of the terrain wind field in the mountainous region,the wind-induced effect of the transmission tower line system and introduces the provisions of the current regulations on the mountain terrain wind field.Based on the existing research and relevant domestic and foreign regulations,the main research content of this paper is proposed.(2)Based on the wind tunnel test study of generalized hilly topography,section line model and natural hilly terrain,this paper discusses the wind speed terrain correction coefficient for generalizing the terrain of hills with different gradients,Vertical wind speed component of the wind field and turbulence changes.Besides,this paper also compares the wind speed terrain correction coefficient of the section line model and natural hilly terrain.Thereafter,this paper has derived the wind field characteristics of generalized hill topography,section line model,and natural hilly terrain.(3)Based on the wind tunnel test study of generalized canyon topography and natural canyon terrain,this paper discusses the changes of wind speed topography correction coefficients along the cross-section and canyon centerline profile of V-shaped symmetric slope gorge topography and natural gorge topography,and compares the wind speed terrain correction coefficients of the two models.Therefore,this paper has derived the wind field characteristics of V-shaped symmetric slope gorge topography and natural gorge topography.(4)This paper utilize harmonic synthesis method,programming through the commercial mathematics software MATLAB to simulate the most unfavorable position wind field in the natural hilly terrain,the natural canyon terrain and the flat terrain wind field under the same flow.Based on the rigid tower model wind tunnel test of the wine glass tower,this paper obtains the body shape factor of the tower body,analyzes and compares the dynamic characteristics of the wine glass tower and the three-tower and four-speed transmission tower line system in different terrains.This paper also respectively compares and analyzes the dynamic time-history response of the transmission tower line system under the hilly topography,flat topography,canyon topography and flat terrain wind field.The results show that the dynamic time-history response of the transmission tower line system under the mountain terrain wind field is larger than the flat terrain,which easily leads to fatigue damage of the transmission tower.(5)Based on the canyon topographic wind field,this paper uses a tuned mass damper to control the wind transmission of the transmission tower line system,calculates and analyzes the optimal frequency ratio and optimal damping ratio TMD.The paper has come to the conclusion that in the canyon terrain,the optimal frequency ratio of TMD is 1.01,the optimal damping ratio is 0.06,and the damping rate is 23.73%.