Hydrodynamic response of a semi-submersible platform to support a wind turbine

Abstract

In this research, a numerical investigation on the hydrodynamic response of a semisubmersible platform, developed by DeepCwind consortium, equipped with the National Renewable Energy Laboratory 5-MW reference wind turbine, and a typical 6-MW wind turbine is conducted. The main objective is to develop a numerical model validated by experimental test results of a semisubmersible platform with mooring lines made of various materials. A commercial software package is employed to model the floating platforms, and a coupled dynamic analysis is carried out on floater motions, mooring lines, and their interactions. The 5-MW numerical model is verified using experimental results of the reduced 1/50th scale semisubmersible platform model conducted by DeepCwind consortium. The results from the numerical model are also compared with FAST programme developed by the National Renewable Energy Laboratory, where an acceptable agreement is achieved to benchmark the parametric study presented herein. A semisubmersible platform with 6-MW wind turbine is designed through hydrostatic and hydrodynamic analyses, using the general arrangement, main structure, and mooring system from the verified 5-MW numerical model. A parametric study is carried out to study the influence of different parameters on the hydrodynamic response of the platform, including total mass, mooring material properties, and wave characteristics. Various mooring lines are examined with particular attention to polymer and synthetic materials to determine which is the most suitable for this platform. Results reveal that using the synthetic mooring lines due to their low Young's modulus provide better performance for the platform compared with other materials investigated in this research.