Cascading collapse of transmission lines

The occurrence of cascades – that is, progressive failures – has been reported in the majority of the serious incidents involving transmission lines worldwide. During cascades, the failure of a line component overloads the structural system, triggering a failure propagation that can lead to the collapse of a considerable number of line supports. This paper provides an overview of the problem of transmission line (TL) cascades. Their classification, main mechanisms and usual protective and mitigation measures are described. Relevant technical literature is also reviewed. The use of a recently developed technique to obtain the non-linear response of multi-span line sections under progressive failure scenarios is detailed. Two case studies are investigated employing this method. The first assesses the effectiveness of a traditional anti-cascade load case, and the second examines the vulnerability of an existing 230 kV TL to longitudinal cascades. © 2018 ICE Publishing: All rights reserved.