The shape design and analysis of floating offshore wind turbine structures with damper structure and shallow draft

Abstract

The floating offshore wind turbines(FOWTs) are considered as a promising candidate due to high-quality of wind energy and environmental friendliness. There are typical three types of conceptual design of FOWTs such as Spar, Semi-submersible, and TLP. Recently, Hywind-OC3 spar and WindFloat semi-submersible type structures as 5MW class have been studied. In the present study, a series of parametric study for several shape design of FOWT have been conducted considering the wide operable water depth by having a shorter draft than one of typical spar and cost effective construction by numerical analysis using a 9-node higherorder boundary element method(HOBEM). In the parametric study, the wind turbine platform which has the truss spar type shape with damper structure to reduce the motion & acceleration responses is suggested. The numerical results for the selected shape design of FOWT were validated through a series of convergence test and model test data. In the series of model tests at ocean engineering basin, MOERI/KIOST, motion and acceleration at Nacelle responses were obtained for regular and irregular waves. The global performance of the model structure has been compared with same class spar-type structure, 5MW Hywind-OC3. Finally, a shape design of FOWT to get more improved global motion performance and technical feasibility was also discussed. Copyright ？ 2013 by the International Society of Offshore and Polar Engineers (ISOPE).