Dynamic Modelling and Response of a Power Cable connected to a Floating Wind Turbine

Abstract. A power cable that connects a floating power plant to the grid is exposed to a dynamic environment that can pose challenging design conditions for the cable. This dynamic environment is caused by the movements of the floating substructure due to a combination of wind, wave and current forces. The power cable model needs to be able to account for its bending and axial stiffness, and hydrodynamic forcing. In this publication a catenary mooring/cable line element with bending stiffness is verified with a reference tool to assure the bending stiffness of a power cable is captured correctly. By using an existing parametric design model, a simple power cable design (in terms of overall cable length) is proposed for the IEA15MW turbine with UMaine floating substructure for a site with a water depth of 82 meter. A simple geometric method is proposed to initialize this complex lazy wave cable design in a dynamic and time domain simulation environment. The hydro-servo-aero-elastic wind turbine simulation environment HAWC2 is then used to establish an estimate of how much movements the combined system (turbine, floater, mooring lines, and power cable) experiences. This study discusses the necessary steps that are to be considered when including the dynamic power cable in the analysis and when adjusting a floating reference wind turbine design to a specific site with different water depth.