Final report for WP4.3: Enhancement of design methods ... - Upwind

UPWIND WP4: Offshore Support Structures and Foundations
9. Development of design requirements
9.1 Literature review of floating offshore standards
A literature review of current design standards relevant to offshore floating structures has been performed, together
with comments on applicability to floating offshore wind turbines (FOWT), in order to provide input for
the standardization of floating wind turbines.
GL Guidelines 2005 – Guideline for the Certification of Offshore Wind Turbines
Scope:
• Guideline applies to the design assessment and certification of offshore wind turbines and offshore
wind farms.
Applicability for FOWT:
• Detailed requirements for design calculations. Description of load cases which cover design situations
and external conditions. Is applicable for FOWT too. Extension to further specific requirements is under
development with focus on stability requirements and mooring applications.
• Restrictions: specific requirements for FOWT (e.g. floating units, mooring) mainly as reference to GL
Rules (cited below).
GL Rules for Classification and Construction 2007 - Part 6 Offshore Technology – Chapter 2 Mobile Offshore
Units
Scope: Requirements for the different types of mobile offshore units as:
• Units connected to the sea bed by anchoring (mooring)
• Units kept on position by dynamic positioning/propelling system
• Units connected by legs in jacked up condition
Applicability for FOWT:
• Requirements for floating and anchored units. Contains mooring requirements
• Restrictions: No wind turbine specific design load case requirements
IEC 61400-3 - Guideline for Offshore Wind Turbines, Edition 1.0 International Electrotechnical Commission
(IEC), Wind Turbines – Part 3: Design requirements of offshore wind turbines, 2009
Scope:
• Guideline for fixed offshore wind turbines
Applicability for FOWT:
• Detailed requirements for design calculations. Description of load cases which cover design situations
and external conditions.
• Restrictions: No specific requirements for FOWT (e.g. floating units, mooring).
• Two extensions have been proposed: DNV - Commentary and amendments to IEC 61400-3 concerning
offshore floating turbines ([117], also included in WP 1A1 as an Annex), and IEC TC88 proposal for
new work item from Korean NC – Standard for floating offshore wind turbines [118].
DNV Energy Report: Guideline for offshore floating wind turbine structures, 2009
Scope:
• This provides requirements and recommendations for design floating support structures for offshore
wind turbines.
Applicability for FOWT:
• Sections in the guideline made mostly reference to the DNV OS-J101, Design of Offshore Wind Turbine
Structures, October 2007 and to other Rules for Offshore Structures
• Restrictions: Specific load cases for floating offshore wind turbines are still under development and
some related aspects are briefly mentioned.
DNV OS-J101, Design of Offshore Wind Turbine Structures, October 2010
Scope:
• Guideline applies to the design assessment and certification of offshore wind turbines and offshore
wind farms.
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