Modeling Sudden Ice Shedding From Conductor Bundles

Abstract

Abstract-Sudden I. INTRODUCTIONHEDDING of the ice accreted on transmission line cables is a recurrent problem in cold regions. The falling of large ice chunks results in high-amplitude vibration of the de-iced cable giving rise to important dynamic forces acting on the transmission line. When a subconductor in a multiconductor bundle sheds, the rotation of the bundle may also be significant, leading to bundle collapse in extreme cases. Bundle collapse occurs when the bundle rotation exceeds a critical angle so that the bundle loses its stability and does not untwist itself after load removal [2], [3]. A review of icerelated dynamic problems on overhead lines, including ice shedding and bundle rolling is provided in [4].Research efforts to understand and simulate the dynamic effects of ice shedding have been carried on for several decades. Reference

Modeling Ice Shedding Propagation on Transmission Lines with or without Interphase Spacers

“…Although ice usually appears on conductors as a distributed load, concentrated loads can be applied on truss elements unlike distributed loads, and the application of concentrated loads simulates more adequately the ice load of the experimental ice shedding tests where the loads were also attached at several discrete points along the span. If these concentrated loads are attached to enough points of the cable, they provide a satisfactory approximation of the distributed ice load and its static and dynamic consequences as was shown in [5]. Ice shedding propagation is then simulated through the removal in a defined sequence of the concentrated loads.…”

“…Therefore, great effort has been made to simulate ice shedding numerically and experimentally on small-scale or full-scale test lines in order to understand the dynamic effects of ice shedding. Numerical models have been developed to simulate ice shedding from a single conductor [2], [3] or from conductor bundles [4], [5]. Experiments were carried out on small-scale experimental setup [2] full-scale test line [6].…”

Influence of Transmission-Line Parameters on High-Amplitude Vibration of Conductor Bundles

“…Although ice usually appears on conductors as a distributed load, concentrated loads can be applied on truss elements unlike distributed loads; furthermore, the applicability of this approach was shown in [7]. Thus, in the static analysis concentrated loads are applied along the span at constant distances.…”

“…In particular, a numerical model developed formerly to simulate ice shedding is applied for a twin bundle of conductors with various line parameters. Ice shedding was simulated numerically on a single conductor in [5] and [10], and on conductor bundles in [6] and [7]. The numerical model of [5] was validated by small-scale experiments; whereas fullscale experiments were carried out in [8] to simulate sudden ice shedding, and in [11] to simulate propagating ice shedding.…”

“…The vertical vibration of bundled conductors was simulated in [6] for different subspan lengths. Bundle rotation was also considered in [7], but the effects of different line parameters on both of vibration and rotation of the conductor bundle have not been investigated in the literature. The goal of this paper is to consider line parameters which have great influence on the severity of vibration, namely span length, number of spacers in a span, and suspension length, and establish how conductor rebound height and bundle rotation depend on these parameters after the application of such sudden load on the line as ice shedding from a conductor.…”