Galloping behaviors of ice-coated conductors under steady, unsteady and stochastic wind fields

Abstract

This paper addresses the similarities and differences between the galloping behaviors of ice-coated conductor transmission lines under steady, unsteady and stochastic wind fields. A finite element model of crescent-shaped ice-coated conductor is first established by using the 3-node isoparametric cable element. The analysis model and numerical integration scheme used in this study are then verified by comparison with the existing experimental data and numerical simulations. In order to efficiently simulate two-dimensional unsteady and stochastic wind fields acting on the ice-coated conductor, the newly-developed spectral representation method based on wavenumber-frequency joint power spectrum is adopted. The probability density evolution method (PDEM) is introduced to explore the statistical characteristics of conductor galloping under stochastic wind field. It is revealed that the unsteady wind field stimulates the self-excited vibration of the ice-coated conductor and further leads to an unstable galloping. However, under the stochastic wind field, the galloping variance of ice-coated conductor is steady and periodic, and the galloping probability density propagates alternately as uni- and bi-modals. These properties are quite different from those exhibited in simplified nonlinear models excited by Gaussian white noises in existing literature. Moreover, the galloping amplitude under stochastic wind field is greatly larger than that under steady wind field. Therefore, an extensive attention should be paid to the safety design of conductor transmission lines in cold regions considering the influence of stochastic wind field.