No abstract

No abstract

A nonlinear finite element method for galloping of iced bundle conductor transmission lines is presented. Wind tunnel tests for galloping of quad bundle conductor segments with crescent-shaped and sector-shaped ice models were carried out, and validity of the finite element method is demonstrated by the consistency of the galloping responses determined by the numerical method and those measured by the wind tunnel tests. Numerical models of four sections of iced transmission lines with different Irvine parameter l 2 , which determines if internal resonance exists, are set up. Galloping of the iced transmission lines in steady wind flow and stochastic wind field is numerically simulated by the presented finite element method. Based on the numerical results, galloping characteristics of the iced transmission lines with and without internal resonance in steady and stochastic wind fields are discussed. It is found that the galloping mode and frequency of an iced quad bundle conductor transmission line in a stochastic wind field are similar to those in a steady wind flow, but the galloping amplitude may be different. Moreover, the Irvine parameter l 2 may be used to estimate some galloping characteristics, such as galloping mode and coupling movement induced by internal resonance.

Iced conductor motion is induced by the aerodynamic instability of these conductors. The unsteady aerodynamic characteristics are different from the steady aerodynamic characteristics. The unsteady aerodynamic coefficients of typical iced conductors’ models under torsional motion are measured by the unsteady wind tunnel test. The unsteady aerodynamic coefficients of crescent-shape and sector-shape iced 4-bundle conductors under different torsional motion frequencies, wind velocities, and ice thicknesses are obtained. Wind test results show that there are significant differences between the unsteady and steady aerodynamic coefficients. The unsteady aerodynamic coefficients curve is a loop which is different from the steady aerodynamic coefficients. In addition, the obvious differences exist between unsteady aerodynamic coefficients of crescent-shape and sector-shape iced bundle conductors. Critical parameters, including torsional motion frequencies, wind velocity, ice shape, and ice thickness, have significant influences on unsteady aerodynamic coefficients. It shows that the wind tunnel experiment results are able to provide necessary data for the investigation of iced bundle conductor motion and their prevention techniques.

No abstract