| dc.description.abstract | This thesis presents a method to upscale the NREL 5 MW reference wind turbine and the OC4 reference semisubmersible from 5 MW to 15 MW. The basis for the upscaling method is an assumption for the overturning moment scaling with turbine power rating. Focusing on the semisubmersible, this allows for upscaling by preserving max static pitch angle, or in other words, by scaling pitch restoring stiffness with the same factor as overturning moment. This was accomplished by increasing column radius, or column distance, or both. Increasing column radius increased the heave natural period and metal mass, while increasing column distance raised the center of gravity and metacentric height but slightly decreased the heave natural period, potentially exposing the platform to resonant effects. Comparison was also made to the VolturnUS-S 15 MW platform, whose design was observed to increase the heave natural period while lowering the center of gravity, addressing issues with scaling column distance. Finally, a method for estimating the upscaled platform parameters for different overturning moment assumptions was developed after observing that the upscaled platform had much greater pitch restoring stiffness than the VolturnUS-S platform. The estimation indicated that for the assumed overturning moment scaling, platform metal mass per unit power would always decrease when upscaling. | en |
