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BS EN IEC 61400-3-2:2025 - TC Tracked Changes. Wind energy generation systems - Design requirements for floating offshore wind turbines, 2025
- 30512904
- A-30428830 [Go to Page]
- undefined
- Annex ZA (normative)Normative references to international publicationswith their corresponding European publications [Go to Page]
- English [Go to Page]
- CONTENTS
- FOREWORD
- INTRODUCTION
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- Figures [Go to Page]
- Figure 1 – Parts of a floating offshore wind turbine (FOWT)
- Figure 2 – Rigid-body motion degrees of freedom of a floating substructure; illustration by Alfred Hicks, National Renewable Energy Laboratory
- 4 Symbols, units and abbreviated terms [Go to Page]
- 4.1 General
- 4.2 Symbols and units
- 4.3 Abbreviated terms
- 5 Principal elements [Go to Page]
- 5.1 General
- 5.2 Design methods
- Figure 3 – Design process for a floating offshore wind turbine (FOWT)
- 5.3 Safety level for FOWT
- 5.4 Safety classes for RNA and tower
- 5.5 Quality assurance
- 5.6 Rotor–nacelle assembly markings
- 5.7 Support structure markings
- 6 External conditions – definition and assessment [Go to Page]
- 6.1 General
- 6.2 Wind turbine classes
- 6.3 Definition of external conditions at a FOWT site [Go to Page]
- 6.3.1 General
- 6.3.2 Wind conditions
- 6.3.3 Marine conditions
- Figure 4 – Definition of water levels [Go to Page]
- 6.3.4 Electrical power network conditions
- 6.3.5 Other environmental conditions
- 6.4 Assessment of external conditions at a FOWT site [Go to Page]
- 6.4.1 General
- 6.4.2 The metocean database
- 6.4.3 Assessment of wind conditions
- Tables [Go to Page]
- Table 1 – Conversion between extreme wind speeds of different averaging periods [Go to Page]
- 6.4.4 Assessment of marine conditions
- 6.4.5 Assessment of other environmental conditions
- 6.4.6 Assessment of electrical network conditions
- 6.4.7 Assessment of soil conditions
- 7 Structural design [Go to Page]
- 7.1 General
- 7.2 Design methodology
- 7.3 Loads [Go to Page]
- 7.3.1 General
- 7.3.2 Gravitational and inertial loads
- 7.3.3 Aerodynamic loads
- 7.3.4 Actuation loads
- 7.3.5 Hydrodynamic loads
- 7.3.6 Sea/lake ice loads
- 7.3.7 Other loads
- 7.4 Design situations and load cases [Go to Page]
- 7.4.1 General
- Table 2 – Design load cases
- Figure 5 – Top-down view of nacelle yaw and nacelle yaw misalignment in a simulation [Go to Page]
- 7.4.2 Power production (DLC 1.1 to 1.6)
- 7.4.3 Power production plus occurrence of fault or loss of electrical network connection (DLC 2.1 – 2.6)
- 7.4.4 Start up (DLC 3.1 to 3.3)
- 7.4.5 Normal shutdown (DLC 4.1 to 4.3)
- 7.4.6 Emergency stop (DLC 5.1)
- 7.4.7 Parked (standstill or idling) (DLC 6.1 to 6.5)
- 7.4.8 Parked plus fault conditions (DLC 7.1 and 7.2)
- 7.4.9 Transport, assembly, maintenance and repair (DLC 8.1 to 8.4)
- 7.4.10 Redundancy check and damage stability (DLC F1.1 to F2.3)
- 7.5 Load and load effect calculations [Go to Page]
- 7.5.1 General
- 7.5.2 Relevance of hydrodynamic loads
- 7.5.3 Calculation of hydrodynamic loads
- 7.5.4 Calculation of sea/lake ice loads
- 7.5.5 Overall damping assessment for support structure response evaluations
- 7.5.6 Simulation requirements
- 7.5.7 Other requirements
- 7.6 Limit state analysis [Go to Page]
- 7.6.1 Method
- Figure 6 – The two approaches to calculate the design load effect [Go to Page]
- 7.6.2 Ultimate strength analysis
- 7.6.3 Fatigue analysis
- Table 3 – Safety factor for yield stress [Go to Page]
- 7.6.4 Serviceability analysis
- 8 Control system
- 9 Mechanical systems
- 10 Electrical system
- 11 Anchor design
- 12 Assembly, transport and installation [Go to Page]
- 12.1 General
- 12.2 Planning
- 12.3 Environmental conditions
- 12.4 Documentation
- 12.5 Transport, receiving, handling and storage
- 13 Commissioning, operation and maintenance [Go to Page]
- 13.1 General
- 13.2 Design requirements for safe operation, inspection and maintenance
- 13.3 Commissioning [Go to Page]
- 13.3.1 General
- 13.3.2 Energization
- 13.3.3 Commissioning tests
- 13.3.4 Records
- 13.3.5 Post commissioning activities
- 13.4 Operator’s instruction manual [Go to Page]
- 13.4.1 General
- 13.4.2 Instructions for operations and maintenance record
- 13.4.3 Instructions for unscheduled automatic shutdown
- 13.4.4 Instructions for diminished reliability
- 13.4.5 Work procedures plan
- 13.4.6 Emergency procedures plan
- 13.5 Maintenance manual
- 14 Stationkeeping systems [Go to Page]
- 14.1 General
- 14.2 Catenary, semi-taut or taut stationkeeping systems
- 14.3 Tendon systems
- 14.4 Synthetic mooring
- 14.5 Stationkeeping system hardware
- 14.6 Dynamic power cable
- 15 Floating stability [Go to Page]
- 15.1 General
- 15.2 Intact static stability criteria
- 15.3 Quasi static evaluation
- 15.4 Dynamic response evaluation
- 15.5 Damage stability criteria
- 16 Materials
- 17 Marine support systems [Go to Page]
- 17.1 General
- 17.2 Bilge system
- 17.3 Ballast system
- Annexes [Go to Page]
- Annex A (informative) Key design parameters for a floating offshore wind turbine (FOWT) [Go to Page]
- A.1 Floating offshore wind turbine (FOWT) identifiers [Go to Page]
- A.1.1 General
- A.1.2 Rotor nacelle assembly (machine) parameters
- A.1.3 Support structure parameters
- A.1.4 Wind conditions (based on a 10-min reference period and including wind farm wake effects where relevant)
- A.1.5 Marine conditions (based on a 3-hour reference period where relevant)
- A.1.6 Electrical network conditions at turbine
- A.2 Other environmental conditions
- A.3 Limiting conditions for transport, installation and maintenance
- Annex B (informative) Guidance on calculation of hydrodynamic loads [Go to Page]
- B.1 General
- B.2 Morison’s equation
- B.3 Diffraction and radiation theory
- B.4 Slam loading
- B.5 Vortex-induced vibrations and motions
- B.6 Appurtenances and marine growth
- B.7 Global analysis and fatigue analysis methods
- B.8 Breaking wave loads
- B.9 Air gap
- Annex C (informative) Floating offshore wind turbine (FOWT) anchor design
- Annex D (informative) Statistical extrapolation of operational metocean parameters for ultimate strength analysis [Go to Page]
- D.1 General
- D.2 Use of IFORM to determine 50-yr significant wave height conditional on mean wind speed
- Figure D.1 – Example of the construction of the 50-year environmental contour for a 3-hour sea state duration [Go to Page]
- D.3 Examples of joint distributions of V and Hs and approximations to the environmental contour
- D.4 Choice of sea state duration
- D.5 Determination of the extreme individual wave height to optionally be embedded in SSS
- Annex E (informative) Corrosion protection [Go to Page]
- E.1 General
- E.2 The marine environment
- E.3 Corrosion protection considerations
- E.4 Corrosion protection systems – Support structures
- E.5 Corrosion protection in the rotor-nacelle assembly
- Annex F (informative) Prediction of extreme wave heights during tropical cyclones [Go to Page]
- F.1 General
- F.2 Wind field estimation for tropical cyclones
- F.3 Wave estimation for tropical cyclones
- Annex G (informative) Recommendations for alignment of safety levels in tropical cyclone regions [Go to Page]
- G.1 General
- G.2 Global robustness level criteria
- G.3 Design load cases
- Table G.1 – Additional load cases for tropical cyclone affected regions
- Annex H (informative) Earthquakes
- Annex I (informative) Model tests
- Annex J (informative) Tsunamis [Go to Page]
- J.1 General
- J.2 Numerical model of tsunami [51], [52]
- Figure J.1 – The calculated result of Equation (J.8) [Go to Page]
- J.3 Evaluation of variance of water surface elevation and current velocity [5]
- Annex K (informative) Redundancy of stationkeeping system
- Annex L (informative) Differing limit state methods in IEC and ISO standards
- Table L.1 – Mapping of limit states in ISO 19904-1 Table 4 and load cases from IEC 61400-3-2
- Annex M (informative) Application of load and load effect logic to floating substructure design [Go to Page]
- M.1 General
- M.2 Typical load computation setups
- M.3 Applied example
- Figure M.1 – Example of load and load effect workflow for a hybrid "beams"and "nodes" floating substructure model setup
- Annex N (informative) Guidance on simulation length and associated parameters [Go to Page]
- N.1 General considerations [Go to Page]
- N.1.1 General
- N.1.2 Initial transient time
- N.1.3 Low-frequency dynamics sampling
- N.1.4 Reference period
- N.2 Simulations for fatigue limit state analysis [Go to Page]
- N.2.1 General
- N.2.2 Response variance and reference period
- N.2.3 Statistical convergence of damage
- N.3 Simulations for extreme limit state analysis [Go to Page]
- N.3.1 General
- N.3.2 Characteristic extreme consistency with the reference period
- N.3.3 Characteristic value variability
- Annex O (informative) Estimation of wave directional spreading by long wave method / single point measurement [Go to Page]
- O.1 Background
- Figure O.1 – A typical 60-min (full-scale) time history spectrum with Hs = 6,18 m and Tp = 10,36 s recorded at the Ocean Engineering Wide Tank, University of Ulsan, Korea (South) [Go to Page]
- O.2 Linear free-wave extraction
- O.3 Second-order calculation
- Annex P (informative) Direction spreading function
- Annex Q (informative) Concrete structures design [Go to Page]
- Q.1 General
- Q.2 Design load cases [Go to Page]
- Q.2.1 Limit states in reinforced concrete design
- Q.2.2 ULS, ALS and FLS load cases
- Q.2.3 SLS load cases
- Q.2.4 Load factors
- Q.3 Design criteria [Go to Page]
- Q.3.1 Material factors
- Q.3.2 ULS, ALS, FLS verifications
- Table Q.1 – Partial factors γF for actions for different limit states
- Table Q.2 – Material factors γm for different limit states and materials [Go to Page]
- [Go to Page]
- Q.3.3 SLS: Watertightness verification
- Q.3.4 SLS: Crack-opening verification
- Q.3.5 SLS: Limitation of stresses
- Table Q.3 – Allowable crack-width for different exposure zones
- Annex R (informative) Relationship between peak wave period and significant wave height in the sea areas affected by swell [Go to Page]
- R.1 General
- R.2 Relationship between wave height and wave period in the sea areas affected by swell
- Figure R.1 – The relationship between significant wave height and significant wave period based on the measurement at Fukushima offshore site [2]
- Annex S (informative) Application of damage stability criteria [Go to Page]
- S.1 Objective
- S.2 Scenario of loss of floating stability
- S.3 Flow of application of new damage stability criteria
- S.4 Definition of target probability of failure (PS)
- Figure S.1 – Concept flow of application of new damage stability criteria [Go to Page]
- S.5 Definition of collision probability (P1)
- Table S.1 – Annual reliability of offshore structures
- Figure S.2 – Concept image of the approaching frequency [Go to Page]
- S.6 Definition of total loss probability by ship collision (P2) [Go to Page]
- S.6.1 Concept of estimation of P2 and PT
- S.6.2 Simplification of FEM analysis
- Figure S.3 – Concept of estimation of P2 and PT in a strict way [Go to Page]
- [Go to Page]
- S.6.3 Estimation of P2 by limit curve
- Figure S.4 – Concept of a limit curve
- Figure S.5 – Concept of the probability of total loss probability by ship collision [Go to Page]
- S.7 Additional countermeasure to reduce P2
- Bibliography [Go to Page]