IEC 61400-3:2009

IEC 61400-3 ®
Edition 1.0 2009-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Wind turbines –
Part 3: Design requirements for offshore wind turbines

Eoliennes –
Partie 3: Exigences de conception des éoliennes en pleine mer

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IEC 61400-3 ®
Edition 1.0 2009-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Wind turbines –
Part 3: Design requirements for offshore wind turbines

Eoliennes –
Partie 3: Exigences de conception des éoliennes en pleine mer

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XF
CODE PRIX
ICS 27.180 ISBN 978-2-88910-514-4
– 2 – 61400-3 © IEC:2009
CONTENTS
FOREWORD.5

INTRODUCTION.7

1 Scope.8

2 Normative references.8

3 Terms and definitions .9

4 Symbols and abbreviated terms .15

4.1 Symbols and units .15
4.2 Abbreviations.16
5 Principal elements .17
5.1 General .17
5.2 Design methods.17
5.3 Safety classes .19
5.4 Quality assurance.19
5.5 Rotor – nacelle assembly markings.20
6 External conditions .20
6.1 General .20
6.2 Wind turbine classes .21
6.3 Wind conditions .21
6.4 Marine conditions .22
6.5 Other environmental conditions.31
6.6 Electrical power network conditions.32
7 Structural design.33
7.1 General .33
7.2 Design methodology .33
7.3 Loads .33
7.4 Design situations and load cases .34
7.5 Load and load effect calculations .51
7.6 Ultimate limit state analysis.54
8 Control and protection system.57
9 Mechanical systems.57
10 Electrical system.58

11 Foundation design .58
12 Assessment of the external conditions at an offshore wind turbine site .59
12.1 General .59
12.2 The metocean database.59
12.3 Assessment of wind conditions.60
12.4 Assessment of waves .62
12.5 Assessment of currents.63
12.6 Assessment of water level, tides and storm surges.63
12.7 Assessment of sea ice .63
12.8 Assessment of marine growth .64
12.9 Assessment of seabed movement and scour.64
12.10 Assessment of wake effects from neighbouring wind turbines.65
12.11 Assessment of other environmental conditions .65

61400-3 © IEC:2009 − 3 −
12.12 Assessment of earthquake conditions .65

12.13 Assessment of weather windows and weather downtime.65

12.14 Assessment of electrical network conditions.65

12.15 Assessment of soil conditions .66

13 Assembly, installation and erection .67

13.1 General .67

13.2 Planning .68

13.3 Installation conditions.68

13.4 Site access .68

13.5 Environmental conditions .68
13.6 Documentation.69
13.7 Receiving, handling and storage.69
13.8 Foundation/anchor systems.69
13.9 Assembly of offshore wind turbine.69
13.10 Erection of offshore wind turbine .69
13.11 Fasteners and attachments .69
13.12 Cranes, hoists and lifting equipment.70
14 Commissioning, operation and maintenance .70
14.1 General .70
14.2 Design requirements for safe operation, inspection and maintenance .70
14.3 Instructions concerning commissioning .71
14.4 Operator’s instruction manual .72
14.5 Maintenance manual.74
Annex A (informative) Key design parameters for an offshore wind turbine.76
Annex B (informative) Wave spectrum formulations.79
Annex C (informative) Shallow water hydrodynamics and breaking waves .84
Annex D (informative) Guidance on calculation of hydrodynamic loads.92
Annex E (informative) Recommendations for design of offshore wind turbine support
structures with respect to ice loads. 105
Annex F (informative) Offshore wind turbine foundation design. 116
Annex G (informative) Statistical extrapolation of operational metocean parameters for
ultimate strength analysis. 117
Annex H (informative) Corrosion protection . 123

Bibliography . 127

Figure 1 – Parts of an offshore wind turbine.
...