Stochastic Dynamic Response of a Cross Rope Transmission Line

Abstract

Cross Rope (CR) structures are increasingly used in High Voltage (HV) and Ultra High Voltage (UHV) transmission lines (TLs). The configuration of this kind of structures consists of two steel truss masts, each of which is grounded by two guy-cables connected at their upper end. The masts present no rigid connection between them: they are only linked by the CR cable which, likewise, supports the insulator chains and therefore the conductors. The implementation of this structural typology in transmission lines is relatively recent and its popularity is rising due to some favorable features when compared to self-supporting towers and other configurations of guyed structures (their low weight and associated low cost stand out). However, despite the recent application of CR structures in power lines around the world – Argentina, Brasil, South Africa, Australia, Canada – many aspects of their response to time-varying excitations have not been studied and documented in detail yet. In this work, a segment of a CR transmission line under stochastic wind load is addressed. The mathematical model for the dynamics of the different main structural elements (tower, insulators and cables) is stated, and the governing differential equations are discretized through the Finite Element Method. For the generation of the spatially and temporally correlated wind load field, the Spectral Representation Method (SRM) is applied. Attention is focused on the effect of the aerodynamic damping on the structural response.