influence of met-ocean conditions on the loads analysis of a Floating wind turbine

Open Access
Barj, Lucie Helene
Graduate Program:
Energy and Mineral Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 19, 2013
Committee Members:
  • Susan W Stewart, Thesis Advisor
  • Jeffrey Brownson, Thesis Advisor
  • Derek Elsworth, Thesis Advisor
  • wind energy
  • floating offshore wind turbine
  • structural analysis
  • loads analysis
  • met-ocean conditions
  • renewable energy
Better wind resources far from the shore and in deeper seas have encouraged the offshore wind industry to look into floating platforms. The International Electrotechnical Commission (IEC) is now working on creating a new standard for floating wind turbines derived from existing standards for land-based and fixed-bottom offshore wind turbines. This work aims to determine the best practices in the loads analysis of floating wind turbines to ensure reliable designs and address the unknown impact of wind/wave misalignment on the designs of floating platforms. In order to provide some guidance on how to take this misalignment into account, this study simulates using FAST [1] all the metocean conditions possible (wind speed, wave height, wave period and wind/wave misalignment) and carries out ultimate and fatigue loads analysis for the OC3-Hywind spar buoy platform [2] and the NREL (National Renewable Energy Laboratory) 5 MW reference wind turbine [3]. From this extensive analysis we are able to determine the impact of misaligned winds and waves on the structure and the importance of taking it into account in the design of a floating platform. Also investigated is which metocean conditions combinations are the most critical for the structural integrity of our floating wind turbine design. [1] NWTC Computer-Aided Engineering Tools (FAST by Jason Jonkman, Ph.D.). [2] J. Jonkman. “Definition of the Floating System for Phase IV of OC3”. NREL/TP-500-47535. NREL: Golden, CO, 2010. [3] J. Jonkman, et al. “Definition of a 5-MW Reference Wind Turbine for Offshore System Development”. NREL/TP-500-38060. NREL: Golden, CO, 2009.