Wind-induced conductor response considering the nonproportionality of generalized aerodynamic damping

Abstract

Aerodynamic damping is a key factor that influences the wind-induced responses of transmission conductors. The inaccurate estimation of aerodynamic damping leads to misunderstanding of conductor response to wind actions. For dynamic response analysis in the frequency domain, the generalized aerodynamic damping matrix used to solve conductor motion is diagonal. This study reanalyzed the conductor generalized aerodynamic damping matrix by considering its horizontal and vertical motions and the coupling effects of different modes. The derived generalized aerodynamic damping was a nondiagonal matrix, and we defined it as nonproportional generalized aerodynamic damping. Variations in the aerodynamic damping ratio and the nonproportionality of generalized aerodynamic damping with wind speed were investigated through numerical studies of single- and triple-span conductors. Triple-span conductors with different span lengths, hanging heights, and initial pretension forces were adopted to discuss the effects of the nonproportionality of generalized aerodynamic damping on estimating the dynamic responses of conductors. Results showed that neglecting the vertical motion of a conductor leads to an overestimation of the aerodynamic damping ratio, especially under high wind speed conditions. The nonproportionality of generalized aerodynamic damping is highest when the incoming wind speed at 10 m is 25 m/s. Ignoring such nonproportionality leads to an overestimation of the resonant responses of conductors but exerts minimal effects on total fluctuating responses mainly contributed by background components. Therefore, for a transmission conductor with a significant resonant response, the nonproportionality effect of generalized aerodynamic damping must be considered. Increasing span length and conductor height or reducing initial pretension force seems to enhance nonproportionality effects on conductor responses.