Theoretical Calculation and Finite Element Simulation of Third Order Vibration Modes of Transmission Line and Tower System

Wind induced disasters cause conductor strand breakage, wire breakage, hardware damage, interphase short circuit, pole breakage, pole reversal and other accidents of overhead transmission lines. This seriously threatens the safe operation of transmission lines. In order to study the cause and mechanism of wind induced vibration of transmission lines and prevent wind induced disasters of transmission lines. Taking JL/G1A-400/35 transmission line as an example, this paper constructs the vibration differential equation of transmission line, and solves the natural frequency of the line through the equation. In addition, the finite element simulation method is used to build the geometric model of the transmission line, and the natural frequency of the line is calculated through modal analysis. By comparing the results of differential equation method and finite element simulation method, it can be found that the calculated natural frequencies are almost the same, and the third-order errors do not exceed 5%, which proves that the calculation of finite element simulation method is reasonable and reliable. In addition, the tower is added to the finite element model of the transmission line to analyze the vibration mode and natural frequency of the system. The simulation results show that the elastic boundary conditions of the tower will reduce the natural frequency of the transmission line. With the increase of vibration frequency order, the influence of iron tower on the natural frequency of transmission line is greater.