Vulnerability Analysis Of Transmission Tower-line System Under Wind Loading

With the rapid development of the economy,the country's demand for electricity and electricity has also increased dramatically.As an important part of the power grid system and the main carrier for transmitting electrical energy,the stable operation of the transmission tower-line system is related to the people's quality of life and national stability.In real life,windstorms are one of the main causes of damage to transmission tower-lines.This is because the transmission tower is a typical high-flex structure,and its natural vibration period is close to the excellent period of wind load,so it is very sensitive to wind loads.However,due to the complexity of the transmission tower-line architecture and the influence of the coupling of the tower lines,the theoretical analysis is difficult,and the field measurement and wind tunnel experiments are not only affected by various complicated factors,but also consume huge human and financial resources.Therefore,the numerical simulation of wind-induced vibration analysis and vulnerability analysis of transmission tower-line structure can provide reliable guidance for theoretical research and scientific experiments on the basis of cost saving.In this paper,several effective methods for finding the shape of overhead transmission lines are proposed.By comparison,the shape-finding iteration method is selected to model the transmission tower-line system of the three towers and four lines,and the dynamic characteristics of the structure are studied by modal analysis.Secondly,through the dynamic time history analysis and response spectrum analysis of the tower-line system under different wind direction angle wind loads,combined with the equivalent static analysis results,the wind vibration response problem under different wind direction angles is explored,and the influence of the cut-off frequency of the pulsating wind on the calculation efficiency and accuracy of the wind-induced response is also explored.Then,this paper studies a variety of finite element models,considering the randomness of material properties and section dimensions,based on the static nonlinear analysis method and probability analysis method,the vulnerability analysis of the transmission tower-line system is carried out,and finally the influence of parameter randomness and wind direction angle on the vulnerability curve and collapse wind speed is explored.On this basis,the paper finally analyzes the vulnerability of the structure based on the IDA analysis method,and explores the nature of the wind and the uncertainty of the structure itself and the uncertainty of the external load on the structural vulnerability.Through the wind-induced vibration response study of the transmission tower-line system,it is found that when the wind load simulation is carried out,the cut-off frequency is selected to meet the requirements of the total wind energy,and also to combine the dynamic characteristics of the structure itself.According to the structural vulnerability analysis,the influence of the randomness of the structural parameters on the collapse wind speed of the transmission tower(line)structure couldn't be ignored,and for the structure of this paper,the most unfavorable wind direction angle is 60 degrees.Compared with the typhoon,the vulnerability results calculated by the good wind are safe,and the basic wind speed error of the collapse can reach more than 10%.For different wind loads,the wind loads should be studied separately.In addition,the uncertainty of external loads and the uncertainty of structural parameters have a significant impact on structural vulnerability,while the impact of external loads is more prominent.