Modelling Multi-Layer OHL Conductors Undergoing Wind-Induced Motion

Utilities aim to improve asset management strategies and enhance the utilization of their assets through low-risk reliable practices. Overhead lines and conductor designs have been evolving to increase systems’ power capacity and mechanical integrity, which have also extended asset lifetimes. Nevertheless, it is still challenging to predict a conductor’s fatigue stresses due to wind-induced vibrations that can help to estimate its useful life. A finite element model (FEM) has been established in COMSOL to study the free and forced wind-induced vibrations and the resultant fatigue on single multi-layer conductors considering their complex round and trapezoidal stranding patterns. The FEM analysis is based on multi-physics accounting for the conductor’s thermal and mechanical aspects as well as material and geometry properties. Consequently, the fatigue is quantified for both inter-layer and inter-wire interactions. The simulations show that free conductor vibrations are dictated by the conductor materials and tension distribution between the core and aluminum strands. The bigger the difference between the material properties of the core and aluminum, the lesser the conductor vibrations, especially when the aluminum becomes slack. In fact, a conductor equipped with carbon core (ACCC), has the best vibration resistance among other conductors with steel core (ACSR) and homogeneous (AAACs). Forced vibration simulations identified non-linear fatigue stresses for round and trapezoidal designs, which is more pronounced in larger conductor sizes. Larger trapezoidal ACSRs exhibit better fatigue resistance compared to smaller and round stranded AAACs.