Research On Fatigue Performance Of Long-Span Transmission Tower-Line System Under Wind Load

Power transmission lines are an important component of the power system,undertaking the task of long-distance,high-load power transmission and efficient distribution.With the continuous expansion of cross-regional power resource allocation scale and scope,the transmission tower-line system tends to have larger span and higher tower.When crossing complex terrain,the large-span transmission line can meet the requirements of high-quality and large-capacity power resources for further distance transmission.However,the lightweight,highly flexible,and low-damped structural characteristics of the large-span transmission towerline system make it prone to adverse vibrations under random wind loads.At the same time,the ductility of the structural components themselves has not been correspondingly improved,resulting in a decrease in the fatigue performance of the structure.Currently,there is limited research on the fatigue performance evaluation and improvement of the large-span transmission tower-line system under wind loads.Therefore,this paper analyzes the wind-induced fatigue performance of the large-span transmission tower-line system based on the in-service ultra-high voltage transmission line project.The fatigue life of the large-span transmission tower-line system considering the actual wind speed and wind direction effects is evaluated based on the damage parameters of the middle and end sections of the tower body components.In addition,this study proposes a bidirectional nonlinear gas-spring tuned mass damper(BNGS-TMD)to improve the wind-induced fatigue performance of the large-span transmission tower-line system,thereby extending the service life of the structure.The main research contents of this paper are as follows:(1)Based on the actual engineering of the large-span transmission line,the meteorological statistics data of the weather station near the project site for nearly 50 years(1951-2020)were obtained,and a wind speed and wind direction joint probability calculation program was compiled using MATLAB to obtain the joint distribution probability of wind speed and wind direction.(2)A finite element model of the large-span transmission tower-line system was established using the finite element software ABAQUS,and the sensitivity analysis of windinduced fatigue was carried out,the sensitive components for fatigue damage analysis were clarified.(3)Based on the rain flow counting method,S-N curve,and linear cumulative damage theory,a fatigue damage calculation program for transmission tower components was compiled,and the stress law of sensitive components was analyzed.The fatigue life of the transmission tower structure was evaluated by considering the damage parameters of the middle and end sections of the tower body components.(4)A bidirectional nonlinear GS-TMD was proposed,a three-dimensional finite element model of the transmission tower-line system with an additional nonlinear damper was established,and wind speed and frequency ratio parameter analysis were carried out to reveal its vibration reduction mechanism.The optimal configuration parameters of the damper were studied,and the wind-induced fatigue performance of the large-span transmission tower-line system with the additional GS-TMD was further analyzed.