Platform and mooring system optimization of a 10 MW semisubmersible offshore wind turbine

In this paper, an optimization procedure is proposed to find platform and mooring system configurations which most effectively reduce the dynamic response of a semisubmersible 10 MW Floating Offshore Wind Turbine (FOWT). This is done by developing an efficient frequency domain simulation model able to account for the viscous drag forces and the contributions to the equation of motion stemming from turbine and mooring lines. The objective function is the value of the Response Amplitude Operator (RAO) at the eigenfrequency of the selected degree of freedom (DoF) of the system. Both parked and power production states are investigated. Feasibility constraints related to mean displacements and moorings layout are considered. Results show that optimized configurations can be found with better performances and smaller platform dimensions with respect to the configuration obtained by scaling up the 5 MW geometry.