Dynamic power cable configuration design for floating offshore wind turbines using gradient-based optimization

Abstract

Power cables transmit the electric energy generated by offshore wind turbines to consumers on land and at sea. The power cables usually lie statically on the seabed to prevent them from moving and being damaged. Since floating offshore wind turbines (FOWTs) are positioned using mooring systems, their power cables are placed from a hang-off location at the floater through the water to the seabed. In this dynamic section, they must withstand environmental loads and the loads induced by the FOWT motions. A minimized power cable length is crucial for low transmission losses during operation, which is a priority during the design of the overall configuration. This work presents a dynamic power cable configuration modeling approach using gradient-based optimization. The applied method is Sequential Least Squares Programming (SLSQP). Its applicability is shown in the example optimization of a tethered lazy-wave dynamic power cable configuration connected to a spar-FOWT. The optimization method is applied with two and three design variables. Steady-state analyses with extreme environmental loads are performed at each iteration, considering three distinct loading directions. The resulting optimized power cable configurations have a shorter cable length than the initial configurations. Dynamic analyses of the optimized configuration show that it satisfies the design limits.