Galloping of Iced Transmission Lines Considering Multi-Torsional Modes and Experimental Validation on a Continuous Model

This study aims to determine the galloping trend of iced transmission lines. A mathematical model considering the first three torsional modes is first established by applying the Galerkin method to the continuous dynamic model. The Hopf bifurcation theory is applied to the linear part of the mathematical model to calculate the critical stability conditions for each mode. Numerical procedures are then implemented on the mathematical model to simulate the galloping feature. An experiment on a continuous model for conductor galloping is designed to validate the above-mentioned galloping feature. The phenomena observed in the wind tunnel test are in good agreement with the theoretical observations. The results show that torsional galloping modifies the numbers of bifurcation points for the in-plane modes. A lower in-plane mode is gradually substituted by a higher one with increasing wind velocity. The theoretical and experimental results are then compared in terms of the galloping frequency and wind velocity range of galloping. By applying the experimental parameters to the theoretical model, the consistency between the theory and the experiment is proven. A convenient method is proposed to predict the wind speed range of galloping and is expected to be applicable for predictions of other critical parameters.