Abstract
In recent years, flashover accidents caused by large swings of overhead conductors that frequently occurred under rain-wind condition, greatly jeopardized the normal operation of power transmission systems. However, the large swing mechanism of overhead conductor under the simultaneous occurrence of rain and wind is not clear yet. Thus, a unified model is proposed with derived stability criterion to analyze the large swing of the overhead conductor. The analytical model is solved by finite element method with the aerodynamic coefficients obtained from simulated rain-wind tests, taking into account the effect of wind velocities, upper rivulet motion, rainfall rates, and rain loads on the large swings of overhead transmission lines. The results show that the proposed model can capture main features of the large swing of overhead conductor, this swing being probably due to the upper rivulet’s motion, by which negative aerodynamic damping occurs at a certain range of wind velocity (10 m/s). Furthermore, the peak swing amplitude of the overhead conductors under rain-wind condition is larger than that under wind only, and the rain loads cannot be neglected.
Highlights
Under normal operating conditions, the effect of swing of overhead transmission lines subjected to wind is low
This implies that the criterion of the along-wind swings in wind flow normal to the overhead conductor axis is the function of the balance angle θ0, the unstable angle θ, the drag coefficient CD (θ0 ), and its derivative
The criterion for the unstable region of the overhead conductor is established for along-wind swings and cross-wind swings in wind flow normal to the
Summary
The effect of swing of overhead transmission lines subjected to wind is low. Geng et al [14] carried out a simulated rainfall experimental test to study the effect of rain intensities and paths on power frequency flashover of air gap on a 1:1 ratio scale of conductor-to-tower structure of air gap. Compared with the field measurements and experimental tests on the large swing of overhead transmission lines, theoretical studies related to aerodynamic characteristics are still very limited. Lou et al [19] established a nonlinear dynamic transmission line model consisting of three-span electrical conductors to investigate the impact of aerodynamic damping on the windage yaw of the transmission line It shows that the aerodynamic damping can reduce the maximum value of the windage yaw significantly, but have no obvious effect on its average values. The analytical model is solved by finite element method with the aerodynamic obtained fromelement simulated rain-wind tests, taking into coefficients account theobtained effect of.
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