Modelling the Dynamic Response of Iced Transmission Lines Subjected to Cable Rupture and Ice Shedding

This study is concerned with accurate numerical modelling of the propagation or progression of ice-shedding phenomena and resulting forces in overhead lines following an initial trigger, such as a controlled shock load applied locally with a cable de-icing device, or uncontrolled shocks due to cable rupture. The ice failure criterion used for the ice deposits in the simulations is based on a maximum effective plastic strain limit. This criterion has been verified in models of reduced- and real-scale single spans subjected to shock loads. After showing the improved performance of this ice failure model, it is applied to the case study of a 120 kV two-circuit line section that failed during a localized ice storm event in 1997. A nonlinear dynamic analysis of the line section is performed which considers ice-shedding effects following the conductor ruptures. The results confirm that considering ice-shedding effects in the iced spans subjected to cable rupture is essential to predict the general dynamic response of the line as the cable ruptures may induce ice shedding. The improved performance of the modelling procedure described in this paper can have practical use in the design of transmission lines in industry.