Research Of Wind-induced Vibration Of Tower-line System Of Power Transmission Tower

The natural vibration period of transmission tower is longer, more close to the period of the wind, is sensitive to wind load, the wind vibration response and the corresponding security has become a research hotspot at present. Transmission tower bear the wire wind pressure and gravity, also bear the wire tension, the existence of the wire affects the dynamic performance of the tower, the wind vibration response and wind vibration coefficient, it is necessary to research the dynamic characteristics, response of the wind vibration and wind vibration coefficient of tower line system through the establishment of power transmission tower line system model, in order to get conclusion which are beneficial to the theory research and practical application. The main research work of this paper are:(l)On the basis of the principle of nonlinear finite element theory and theory of looking for shape of transmission line conductor, shape of transmission line is completed in ANSYS. The finite element model of a angle steel tower line system and a steel tube combination tower line system are carried on separately.(2)Based on AR method, consider Kaimal pulsating wind spectrum and spatial three-dimensional coherency function of the Davenport, and use MATLAB to realize simulation of pulse wind speed of the multidimensional space correlation multipoint. Simulation of fluctuating wind power spectrum tallies with the target power spectrum, their trend is consistent, Regression model which this paper adoptted to simulate wind speed time history results are accurate and reliable, and in this paper, taking the wind speed time history simulation parameters is reasonable. Then use Bernoulli formula of the wind pressure and wind speed transformation into nodes will eventually wind speed wind load time history.(3)Using the subspace iteration method in the ANSYS, dynamic characteristics of the tower line system is analyzed and contrasted with the characteristics of single tower, found the mass contribution of the wire is greater than its stiffness contribution in the X direction(transverse), the stiffness contribution of the wire is greater in the Z direction (in the wire direction) than in the X direction.(4)Using the Newmark-method in ANSYS, a wind vibration response of transmission tower tower line system calendar calculation and analysis, get the node displacement and acceleration response, and has made the contrast and double tower response, find power lines on stiffness of the transmission tower there is a significant contribution. In addition to the element internal force, analyzed the different span tower line system of the internal force, discusses the effect of span on the internal forces of the tower line system, found the time history analysis under the action of axial force maximum and average wind axial force ratio of N2/N1decreases with the increase of span, the standard calculation of axial force and the ratio of the average wind under the action of axial force N3/N1is not changing with the span, and the span of N2/Nlless than N3/N1.(5) The studies have shown that the wind vibration coefficient β of the tower line system decreases with the increase of the span, and the wind vibration coefficient βof the single pylon tower remains almost unchanged with the changing of span; and the wind vibration coefficients βof the tower line system under the each span are less than those in the single pylon tower line system. For the provisions of wind vibration coefficient β of the transmission tower under the60m, the regulation of "Overhead transmission line tower structure design technology norms" is accurate, but for the wind vibration coefficient β(z) of the transmission tower up more than60m, it is conservative. When designing, we can be appropriate to reduce the wind vibration coefficient values, according to the calculated β(z) in the tower line system model.