SIST EN 61400-3:2010

SLOVENSKI STANDARD
SIST EN 61400-3:2010
01-januar-2010
9HWUQHWXUELQHGHO=DKWHYH]DQDþUWRYDQMHYHWUQLKWXUELQQDPRUMX,(&

Wind turbines -- Part 3: Design requirements for offshore wind turbines
Windenergieanlagen – Teil 3: Auslegungsanforderungen für Windenergieanlagen auf
offener See
Eoliennes -- Partie 3: Exigences de conception des éoliennes en pleine mer
Ta slovenski standard je istoveten z: EN 61400-3:2009
ICS:
27.180 Sistemi turbin na veter in Wind turbine systems and
drugi alternativni viri energije other alternative sources of
energy
SIST EN 61400-3:2010 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 61400-3:2010

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SIST EN 61400-3:2010

EUROPEAN STANDARD
EN 61400-3

NORME EUROPÉENNE
April 2009
EUROPÄISCHE NORM

ICS 27.180


English version


Wind turbines -
Part 3: Design requirements
for offshore wind turbines
(IEC 61400-3:2009)


Eoliennes -  Windenergieanlagen -
Partie 3: Exigences de conception Teil 3: Auslegungsanforderungen
des éoliennes en pleine mer für Windenergieanlagen auf offener See
(CEI 61400-3:2009) (IEC 61400-3:2009)




This European Standard was approved by CENELEC on 2009-04-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: avenue Marnix 17, B - 1000 Brussels


© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61400-3:2009 E

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SIST EN 61400-3:2010
EN 61400-3:2009 – 2 –
Foreword
The text of document 88/329/FDIS, future edition 1 of IEC 61400-3, prepared by IEC TC 88, Wind
turbines, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 61400-3 on 2009-04-01.
This European Standard is to be read in conjunction with EN 61400-1:2005.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2010-01-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2012-04-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61400-3:2009 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60034 NOTE  Harmonized in EN 60034 series (partially modified).
IEC 60038 NOTE  Harmonized as HD 472 S1:1989 (modified), with the following title “Nominal voltages for
low-voltage public electricity supply systems”.
IEC 60146 NOTE  Harmonized in EN 60146 series (not modified).
IEC 60204-1 NOTE  Harmonized as EN 60204-1:2006 (modified).
IEC 60204-11 NOTE  Harmonized as EN 60204-11:2000 (not modified).
IEC 60227 NOTE  Is related to HD 21 series (not equivalent).
IEC 60245 NOTE  Is related to HD 22 series (not equivalent).
IEC 60269 NOTE  Harmonized in EN 60269 series (modified).
IEC 60364 NOTE  Harmonized in HD 384/HD 60364 series (modified).
IEC 60439 NOTE  Harmonized in EN 60439 series (partially modified).
IEC 60446 NOTE  Harmonized as EN 60446:1999 (not modified).
IEC 60529 NOTE  Harmonized as EN 60529:1991 (not modified).
IEC 61000-6-1 NOTE  Harmonized as EN 61000-6-1:2007 (not modified).
IEC 61000-6-2 NOTE  Harmonized as EN 61000-6-2:2005 (not modified).
IEC 61000-6-4 NOTE  Harmonized as EN 61000-6-4:2007 (not modified).
IEC 61310-1 NOTE  Harmonized as EN 61310-1:1995 (not modified).
IEC 61310-2 NOTE  Harmonized as EN 61310-2:1995 (not modified).
IEC 61400-21 NOTE  Harmonized as EN 61400-21:2002 (not modified).
__________

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SIST EN 61400-3:2010
– 3 – EN 61400-3:2009
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 60721-2-1 1982 Classification of environmental conditions -

+ A1 1987 Part 2-1: Environmental conditions HD 478.2.1 S1 1989
appearing in nature - Temperature and
humidity


IEC 61400-1 2005 Wind turbines - EN 61400-1 2005
Part 1: Design requirements


IEC 62305-3 2006 Protection against lightning - EN 62305-3 2006
(mod) Part 3: Physical damage to structures and + corr. September 2008
life hazard + A11 2009


IEC 62305-4 2006 Protection against lightning - EN 62305-4 2006
Part 4: Electrical and electronic systems + corr. November 2006
within structures


ISO 2394 1998 General principles on reliability for - -
structures


ISO 2533 1975 Standard atmosphere - -


ISO 9001 2000 Quality management systems - EN ISO 9001 2000
Requirements


ISO 19900 2002 Petroleum and natural gas industries - EN ISO 19900 2002
General requirements for offshore structures


ISO 19901-1 2005 Petroleum and natural gas industries - EN ISO 19901-1 2005
Specific requirements for offshore
structures -
Part 1: Metocean design and operating
considerations


ISO 19901-4 2003 Petroleum and natural gas industries - EN ISO 19901-4 2003
Specific requirements for offshore
structures -
Part 4: Geotechnical and foundation design
considerations


1) 2)
ISO 19902 - Petroleum and natural gas industries - Fixed EN ISO 19902 2007
steel offshore structures


ISO 19903 2006 Petroleum and natural gas industries - Fixed EN ISO 19903 2006
concrete offshore structures



1)
Undated reference.
2)
Valid edition at date of issue.

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SIST EN 61400-3:2010

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SIST EN 61400-3:2010
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 2-8318-1025-2
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 61400-3:2010
– 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

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SIST EN 61400-3:2010
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.10
Figure 2 – Design process for an offshore wind turbine.19
Figure 3 – Definition of water levels.29
Figure 4 – The two approaches to calculate the design load effect.55
Figure B.1 – PM spectrum .80
Figure B.2 – Jonswap and PM spectrums for typical North Sea storm sea state .81
Figure C.1 – Regular wave theory selection diagram.84
Figure D.1 – Breaking wave and cylinder parameters.96
Figure D.2 – Oblique inflow parameters .96
Figure D.3 – Distribution over height of the maximum impact line force (γ = 0°) .98

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SIST EN 61400-3:2010
– 4 – 61400-3 © IEC:2009
Figure D.4 – Response of model and full-scale cylinder in-line and cross-flow (from
reference document 4) .100
Figure E.1 – Ice force coefficients for plastic limit analysis (from reference document 6) . 110
Figure E.2 – Serrated load profile (T = 1/f or 1/f ) . 113
0,1 N b
Figure G.1 – Example of the construction of the 50-year environmental contour for a 3-hour
sea state duration. . 118

Table 1 – Design load cases .36
Table 2 – Design load cases for sea ice .50
Table 3 – Partial safety factors for loads γ .56
f
Table 4 – Conversion between extreme wind speeds of different averaging periods .61
Table C.1 – Constants h and h and normalised wave heights h as a function of H .87
1 2 x% tr
Table C.2 – Breaking wave type .90

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SIST EN 61400-3:2010
61400-3 © IEC:2009 − 5 −
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

WIND TURBINES –

Part 3: Design requirements for offshore wind turbines


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61400-3 has been prepared by IEC technical committee 88: Wind
turbines.
This part is to be read in conjunction with IEC 61400-1:2005, Wind turbines – Part 1: Design
requirements.
The text of this standard is based on the following documents:
FDIS Report on voting
88/329/FDIS 88/338/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

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SIST EN 61400-3:2010
– 6 – 61400-3 © IEC:2009
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 61400 series, published under the general title Wind turbines, can be
found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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SIST EN 61400-3:2010
61400-3 © IEC:2009 − 7 −
INTRODUCTION
This part of IEC 61400 outlines minimum design requirements for offshore wind turbines and is
not intended for use as a complete design specification or instruction manual.
Several different parties may be responsible for undertaking the various elements of the
design, manufacture, assembly, installation, erection, commissioning, operation and
maintenance of an offshore wind turbine and for ensuring that the requirements of this
standard are met. The division of responsibility between these parties is a contractual matter
and is outside the scope of this standard.
Any of the requirements of this standard may be altered if it can be suitably demonstrated that
the safety of the system is not compromised. Compliance with this standard does not relieve
any person, organization, or corporation from the responsibility of observing other applicable
regulations.

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SIST EN 61400-3:2010
– 8 – 61400-3 © IEC:2009
WIND TURBINES –

Part 3: Design requirements for offshore wind turbines



1 Scope
This part of IEC 61400 specifies additional requirements for assessment of the external
conditions at an offshore wind turbine site and it specifies essential design requirements to
ensure the engineering integrity of offshore wind turbines. Its purpose is to provide an
appropriate level of protection against damage from all hazards during the planned lifetime.
This standard focuses on the engineering integrity of the structural components of an offshore
wind turbine but is also concerned with subsystems such as control and protection
mechanisms, internal electrical systems and mechanical systems.
A wind turbine shall be considered as an offshore wind turbine if the support structure is
subject to hydrodynamic loading. The design requirements specified in this standard are not
necessarily sufficient to ensure the engineering integrity of floating offshore wind turbines.
This standard should be used together with the appropriate IEC and ISO standards mentioned
in Clause 2. In particular, this standard is fully consistent with the requirements of IEC 61400-
1. The safety level of the offshore wind turbine designed according to this standard shall be at
or exceed the level inherent in IEC 61400-1. In some clauses, where a comprehensive
statement of requirements aids clarity, replication of text from IEC 61400-1 is included.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60721-2-1:1982, Classification of environmental conditions – Part 2-1: Environmental
conditions appearing in nature. Temperature and humidity
Amendment 1:1987
IEC 61400-1:2005, Wind turbines – Part 1: Design requirements
IEC 62305-3:2006, Protection against lightning – Part 3: Physical damage to structures and life
hazard
IEC 62305-4:2006, Protection against lightning – Part 4: Electrical and electronic systems
within structures
ISO 2394:1998, General principles on reliability for structures
ISO 2533:1975, Standard Atmosphere
ISO 9001:2000, Quality management systems – Requirements
ISO 19900:2002, Petroleum and natural gas industries – General requirements for offshore
structures

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SIST EN 61400-3:2010
61400-3 © IEC:2009 − 9 −
ISO 19901-1:2005, Petroleum and natural gas industries – Specific requirements for offshore
structures – Part 1: Metocean design and operating conditions
ISO 19901-4:2003, Petroleum and natural gas industries – Specific requirements for offshore
structures – Part 4: Geotechnical and foundation design considerations
ISO 19902, Petroleum and natural gas industries – Fixed steel offshore structures
ISO 19903: 2006, Petroleum and natural gas industries – Fixed concrete offshore structures
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply in addition to
those stated in IEC 61400-1.
3.1
co-directional (wind and waves)
acting in the same direction
3.2
current
flow of water past a fixed location usually described in terms of a current speed and direction
3.3
design wave
deterministic wave with a defined height, period and direction, used for the design of an
offshore structure. A design wave may be accompanied by a requirement for the use of a
particular periodic wave theory
3.4
designer
party or parties responsible for the design of an offshore wind turbine
3.5
environmental conditions
characteristics of the environment (wind, waves, sea currents, water level, sea ice, marine
growth, scour and overall seabed movement, etc.) which may affect the wind turbine behaviour
3.6
external conditions (wind turbines)
factors affecting operation of an offshore wind turbine, including the environmental conditions,
the electrical network conditions, and other climatic factors (temperatu
...