On the Response of a Spar Floating Wind Turbine Under the Occurrence of Extreme Events

In this paper, the quasi-determinism theory is applied for the computation of forces jointly generated from wind and waves. A coupled 3-degree-of-freedom (3-dofs) model of a floating spar-type 5 MW wind turbine is herein studied subject to wind and waves under the occurrence of wind and sea. Numerical simulations of forces in the time domain are carried out using FAST software, taking into account the hydrodynamic characteristics of the floater obtained in the frequency domain by WAMIT through panel method. Equations of motion are integrated by means of a Runge-Kutta routine and time histories and statistics of responses of the model are calculated. Further, a quasi-deterministic approach is followed in order to predict the short-term responses under the occurrence of extreme (low probability, given a fixed sea state) events and results finally compared with those obtained from the more time-consuming numerical simulations.