Floating Offshore Wind Turbine Operations in Arctic Conditions

Abstract

Offshore wind energy is receiving increased attention as a promising renewable energy source day by day, and the research in the field of designing the floating platforms to support floating offshore wind turbine (FOWT) has become very important. The evaluation of the dynamic stability of a FOWT in a challenging marine environment is the platform's capacity to maintain its initial position. These are often assessed in terms of the floating platform's rigid body dynamic response, which supports the entire FOWT. This study uses Ansys AQWA to analyze the dynamic response of the NREL – 5 MW reference wind turbine powered by a SPAR buoy platform at an offshore location well suited for production of offshore wind energy in Arctic region.

An offshore location in the Arctic region was selected systematically and meteorological data for past 7 years (2015 – 2021) was extracted to model operating conditions in Ansys AQWA. Firstly, best design configuration was chosen for Spar hull to support the basis of selection and designing the Spar buoy platform through numerical simulations and then full-scale model including the mooring system for FOWT was developed to evaluate the dynamic response in mean and extreme operating conditions. Time domain response was generated using Ansys AQWA in every Degree of freedom (Heave, Surge, Sway, Roll, Pitch and Yaw). The response was then analyzed and concluded the effective dynamic stability of the FOWT. The results indicate that the design of the spar platform is reasonable and has good hydrodynamic performance.

The full report also emphasizes the importance of operating conditions, examining the structural dynamic behavior, post-tensioned load on mooring lines, and motion of the whole structure. The conclusion of the thesis includes findings obtained from the study, implications for designed floating platform for FOWT and detailed resonant frequencies for each DOF. It also incorporates ideas for future research and guides employing hydrodynamic numerical modelling to design and construct more efficient, resilient, and durable floating platforms.