Finite Element Design Study of Dynamics in Submarine Power Cables for Offshore Renewable Wind Energy

Abstract The future of energy in Ireland will include significant emphasis on offshore renewable energy due to the country’s excellent marine resources, with a potential 70 GW of ocean energy available within 100 km of the Irish coastline [1]. A key challenge to improving uptake of offshore wind energy is the reliability of power transmission via submarine power cables (SPCs). Dynamic cables associated with floating offshore wind turbines are critical infrastructure that consist of a complex arrangement of sub-components with different functions, including strength, insulation and corrosion resistance. Fretting, wear, and fatigue have been demonstrated as key contributing factors to damage and failure of cable conductors within laboratory testing of SPCs [2]. This paper presents a finite element design study for dynamic power cables based on a systematic model development relating an offshore submarine cable with a representative laboratory test arrangement. Initially a global finite element model is developed to replicate a floating wind turbine with attached dynamic cable via Flexcom [3] and OpenFAST [4] (without fretting fatigue damage) operating in an offshore marine environment. Simplified SPC and multi-strand wire models are developed using Abaqus [5] to understand the localised fretting conditions between individual wires. The results of these models are implemented into a localised and highly detailed frictional contact model, constructed to represent a crossed-cylinder laboratory fretting test arrangement, using results from the global assessment as boundary conditions. The localised finite element analysis (FEA) is used to predict potential fretting fatigue damage. This research aims to develop a systematic methodology for fretting fatigue in SPC copper conductors, helping to identify suitable design aspects (e.g., lay angle, lay direction, wire diameter, and number of layers) for reduction of fretting fatigue damage and extension of cable service life.