Dynamic characteristic of ice-shedding on UHV overhead transmission lines

The dynamic effect of ice-shedding can cause mechanical damage and electrical faults due to the clashing of conductors. The ice-shedding problem is more serious on UHV lines as the quantity of bundled conductors and the cross-sectional areas of the conductors are larger. Consideration of the ice-shedding problems is very important in determining the alignment of the conductors, the type of towers and the configurations of spans. In this paper, the actual dynamic responses of the conductor displacement and tension are acquired through physical testing, in which the natural ice formed on conductors is simulated by lumped loads hanging on the conductors, using full-size multi-span configurations. Various ice- shedding modes are considered. Furthermore, a multiple degrees of freedom dynamic model of the multi-span lines, suitable for analyzing ice-shedding, has been developed and gives good agreement between the computation and test results, which demonstrates the validity of both the use of lumped-loads in the tests and of the numerical simulation program, which may therefore be applied to both existing UHV transmission lines and the design of new lines.