Platform and moorings modelling and optimization procedures for large semisubmersible floating offshore wind turbines

Floating Offshore Wind Turbines (FOWTs) are ground-breaking systems in the renewable sector, capable to exploit wind energy in deep-water areas, where the resource is stronger and abundant with respect to onshore and near-cost sites. In this work, a coupled Frequency-Domain (FD) model of the entire system is developed and validated against time-domain simulations. The FD model is implemented in site-specific optimization procedures performed by means of Genetic Algorithm (GA, targeted at reducing the costs of the substructure without an uncontrolled penalization of the structural performances. Two installations sites in the Mediterranean Sea are chosen for the analysis. Results show that the optimization strategies give useful information about the influences of platform and mooring characteristics on the system response. Moreover, it is proved that the costs can be reduced of about the 45%, implying the reduction of the Levelized Cost Of Electricity.