Assessing Mechanical Stresses in Dynamic Power Cables for Floating Offshore Wind Farms

Abstract

Floating offshore wind offers a promising potential in the development of renewable energies. One of the key component of offshore wind farms projects is the inter-array power cable. Additionally, the dynamic behavior of floating support under offshore environmental conditions requires dynamic power cable structures which have to withstand both fatigue and extreme loads over its lifetime. Both global and local analyses are required to properly design a dynamic power cable. Indeed, the axial, bending and torsion loads due to environmental conditions (waves and current) and the floating support motion are calculated from a global model by using a dedicated software. Then, the global loading has to be transferred to local sub-models in order to calculate stresses acting on the different components of the power cable. This paper describes a 3D finite elements (FE) model dedicated to a detailed prediction of stresses in an armoured power cable. The loads under extreme environmental conditions are first evaluated from a global analysis. The local model, developed in a commercial FE software, uses periodic boundary conditions to reduce the computational costs and accurately model cables with constant curvatures in space. The model includes contact pressure and friction effects between all cable components, as well as potential lateral contacts between adjacent armour wires, and the radial stiffness of the cable core. The applicative example, focusing on the amour layers, illustrates the potential of the model.