Increasing numbers of floating offshore wind turbines are planned to be built in the coming years due to their high potential to generate massive amounts of clean energy from ocean-wind. In the present study, a numerical prediction tool has been developed for the coupled dynamic analysis of a FOWT (floating offshore wind turbine) system in time domain including aero-loading, blade-rotor dynamics and control, tower elasticity, mooring dynamics, and platform motions. A mono-column TLP design with 5MW turbine is selected as an example case study. In case of the TLP type floater, it is seen that the interaction between an elastic tower and platform motion is very important in view of shifting natural frequencies and aero-dynamic excitations and damping. Those coupling effects can be clearly identified by comparing the elastic tower results with the rigid tower results. The developed technology and numerical tools are readily applicable to the design of any new FOWTs in any combinations of irregular waves, dynamic winds, and steady currents.
Wind is the fastest growing clean and renewable energy source. Until recently, most of the wind-farm development has been limited to the land space. However, the on-land wind farms also have many negative features, such as lack of available space, noise restriction, shade, visual pollution, limited accessibility in mountainous areas, community opposition, and regulatory problems. Therefore, many countries in Europe started to build wind turbines in coastal waters, and so far most offshore wind farms have been installed in relatively shallow-water areas less than 40-m depth by using bottom-fixed-type base structures. Recently, several countries started to plan offshore floating wind farms. Although they are considered to be more difficult to design, wind farms in deeper waters are in general less sensitive to space availability, noise restriction, visual pollution, and regulatory problems. They are also exposed to much stronger and steadier wind fields to be more effective.
