Analysis Of Mechanical Characteristics Of Typical Transmission Tower-Line System

In recent years,the continuous development of high-voltage power transmission technology,transmission accidents occur from time to time,seriously jeopardizing the safety of the power grid system.In this paper.a 500kV transmission line in a certain area of Yunnan Province is taken as the research object.Based on ANSYS finite element software,a full-scale three-tower two-line transmission tower-line system model is constructed to analyze the static and dynamic characteristics and stability of the transmission tower-line system.First of all,based on the research of scholars at home and abroad,according to the force characteristics of the transmission tower-line structure under actual working conditions,the members are regarded as the space beam unit beaml 88,and the direct modeling of the transmission tower is adopted.,From the bottom to the top of the segmented modeling,for the overhead conductor by constructing multiple nodes and then connected in order to complete the construction of the finite element model of the transmission tower-line system.Secondly,under different wind speeds and wind direction angles,the static characteristics of the transmission tower-line system are analyzed,and the change rule of the maximum displacement of the conductor under wind load is obtained.The results show that when the wind speed is less than 13 m/s,the influence of the wind speed on the transmission line is small,mainly as the effect of the weight of the conductor;when the wind speed is greater than 13 m/s,it gradually changes into the influence of the wind speed on the conductor.Finally,the fitting relationship tool cftool is used to obtain the functional relationship between wind speed and wire displacement.The exponential function or power function is used as the optimization choice to achieve arbitrary conversion between each other.Then,the transmission tower and tower-line system are analyzed for their dynamic characteristics,and the corresponding natural frequency and mode shapes are obtained.The results show that as the order increases,both the single tower and tower-line system modes will change from a single mode to a mixed mode;the first-order natural frequency of the transmission tower-line system(plus ground)changes relative to the single tower.The rate is 93.3%.When the influence of the ground line is not considered.the natural frequency change rate is 93.98%,and the change trend of the natural frequency change rate is gentler and more reasonable as the order increases.Finally,stability analysis is performed on different V-type insulator strings at different wind speeds.Research indicates When the PH/GV coefficient is approximately 2.34,the stress on the leeward side will be minimized,and buckling changes will occur.By comparison,it is known that within a certain range of angles,the smaller the angle between the quadrupole insulator V string and the vertical plane,the smoother the stress diagram,and the more stable the overall performance,thus providing a strong basis and suggestions for improving the design of the insulator V string.