Effects of aerodynamic coupling and non-linear behaviour on galloping of ice-accreted conductors

Hisato Matsumiya*, Tomomi Yagi, John H G Macdonald

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Wind action on ice-covered transmission lines causes galloping, which is a problem because it can introduce interphase short circuits and cause fatigue of the cross-arms of the power line’s towers and insulators. The galloping phenomenon is characterised by a combination of large-amplitude, low-frequency vertical, horizontal, and torsional oscillations. To better understand the dynamic responses of vertical, horizontal and torsional 3-degree-of-freedom (DoF) galloping on four-bundled conductors, time–history analyses were conducted for 2D systems of varying DoFs and frequency ratios. The fundamental characteristics of the conductor’s non-linear 1-DoF vertical response were analysed via time–history analysis, indicating that large oscillations were caused by inclusion of an angular range of relative angle of attack with a high negative lift-coefficient slope. By considering the energy balance of the vertical motion over one oscillation period, we estimated the stable and unstable limit-cycle amplitudes. Then, by comparing the results of the 1-, 2-, and 3-DoF systems, we clarified the effect of aerodynamic coupling on 3-DoF galloping. The oscillation types in the 3-DoF systems were categorised as vertical–horizontal 2-DoF coupling oscillations, vertical–torsional 2-DoF coupling oscillations, and vertical 1-DoF oscillations according to the stationary torsional angle. Finally, we indicated the coupling effects on vertical oscillation by considering the energy balance of the vertical motion with the defined amplitudes and phase differences of the horizontal and torsional motions. The vertical amplitude of the vertical–horizontal 2-DoF coupling oscillation can become very large if the horizontal amplitude increases and the phase difference between horizontal and vertical displacements approaches 180°. Meanwhile, the range of the stationary torsional angle in which the vertical–torsional 2-DoF coupling oscillation occurs becomes wide as the phase difference between the torsional and vertical displacements approaches 90°. However, without horizontal motion, the vertical amplitude has a limited value, even if the torsional amplitude becomes large.
Original languageEnglish
Article number103366
Number of pages21
JournalJournal of Fluids and Structures
Volume106
Early online date2 Sep 2021
DOIs
Publication statusPublished - Oct 2021

Bibliographical note

Funding Information:
The authors are grateful to Dr. Takashi Nishihara (Central Research Institute of Electric Power Industry) for suggesting the topic addressed in this study and for helpful discussions on the mechanisms of non-linear oscillations.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • Aerodynamic coupling
  • Energy balance
  • Four-bundled conductor
  • Galloping amplitude
  • Ice-accretion
  • Overhead transmission lines

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