EN IEC 61400-1:2019/FprA1:2025

SLOVENSKI STANDARD
SIST EN IEC 61400-1:2019/oprA1:2024
01-januar-2024
Sistemi za proizvodnjo energije na veter - 1. del: Zahteve za načrtovanje -
Dopolnilo A1
Wind energy generation systems - Part 1: Design requirements - Amendment 1
Windenergieanlagen - Teil 1: Auslegungsanforderungen
Systèmes de génération d'énergie éolienne - Partie 1: Exigences de conception
Ta slovenski standard je istoveten z: EN IEC 61400-1:2019/prA1:2023
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
SIST EN IEC 61400-1:2019/oprA1:2024 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

SIST EN IEC 61400-1:2019/oprA1:2024

SIST EN IEC 61400-1:2019/oprA1:2024
88/982/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61400-1/AMD1 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2023-11-03 2024-01-26
SUPERSEDES DOCUMENTS:
88/961/RR
IEC TC 88 : WIND ENERGY GENERATION SYSTEMS
SECRETARIAT: SECRETARY:
Denmark Mrs Christine Weibøl Bertelsen
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

Other TC/SCs are requested to indicate their interest, if any, in
this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for Vote
(CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clauses to
be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC clauses.
(See AC/22/2007 or NEW GUIDANCE DOC).

TITLE:
Amendment 1 – Wind energy generation systems – Part 1: Design requirements

PROPOSED STABILITY DATE: 2025
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

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CONTENTS
FOREWORD . 3
1 Normative references . 5
2 Terms and definitions . 5
3 Symbols and abbreviated terms . 5
6.3 Wind conditions . 6
6.3.1  General . 6
6.3.3.2  Extreme wind speed model (EWM) . 8
7.4.1 General . 8
7.4.7 Parked (standstill or idling) (DLC 6.1 to 6.4) . 8
7.6.1.3 Partial safety factor for consequences of failure and component classes . 9
7.6.2.2 Partial safety factors for loads . 9
7.6.2.4 Partial safety factors for resistances where recognized design codes are not
available . 9
7.6.2.5 Partial safety factors for materials where recognized design codes are
available . 9
7.6.3.4 Partial material factors where recognized design codes are available . 9
10.12  Electro Magnetic Compatibility (EMC) . 11
10.12.1  Introduction . 11
10.12.2  EMC design requirements . 11
11.3.2  Wind condition parameters . 12
11.3.4 Data evaluation . 12
11.9.2 Assessment of the fatigue load suitability by reference to wind data . 12
11.9.3 Assessment of the ultimate load suitability by reference to wind data . 13
11.10 Assessment of structural integrity by load calculations with reference to site-
specific conditions . 14
Annex B . 14
B.1 General . 14
B.2 Power production (DLC 1.1 to 1.9) . 15
Annex E . 15
L.2 Ice mass effects on wind turbine blades . 16
L.4 Reference documents and bibliography . 17
Annex N . 17
N.1 General . 17
N.2 Reference documents and bibliography. 18

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND TURBINES –
Part 1: Design Requirements
AMENDMENT 1
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
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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 document may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
Amendment 1 to IEC 61400-1:2019 has been prepared by IEC technical committee 88: Wind
energy generation systems.
The text of this Amendment is based on the following documents:
Draft Report on voting
XX/XX/XXXX XX/XX/XXX
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Amendment is English.

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This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications/.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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1 1 Normative references
2 2 Terms and definitions
3 For the purposes of this document, the terms and definitions given in IEC 61400-1:2019 and
4 the following apply.
5 ISO and IEC maintain terminological databases for use in standardization at the following
6 addresses:
7 • IEC Electropedia: available at http://www.electropedia.org/
8 • ISO Online browsing platform: available at http://www.iso.org/obp
9 Add
10 damage equivalent load
11 Constant amplitude load derived from the load spectrum and a given S-N curve exponent that
12 results in an equivalent fatigue damage
13 reference loads
14 The loads that had been utilised for detailed structural verification of the wind turbine
15 components are called reference loads.
16 serviceability
17 ability of a structure or structural element to perform adequately for normal use under all
18 expected actions
19 serviceability limit state
20 state which corresponds to conditions beyond which specified service requirements for a
21 structure or structural element are no longer met
22 S1 - SLS characteristic load
23 serviceability limit state load level equal to the characteristic value of the loads from ultimate
24 limit states classified as N (Normal)
-4
26 S2 - SLS 10 frequent load case
-4
27 serviceability limit state load level for frequent actions, which are exceeded for 10 of the
28 lifetime,
-2
29 S3 - SLS 10 frequent load case
30 serviceability limit state load level for the equivalent to frequent actions, which are exceeded
-2
31 for 10 of the lifetime.
32 3 Symbols and abbreviated terms
33 4.2 Abbreviated terms
34 Add
35 DEL Damage equivalent load, 𝑆𝑆 , determined from the approach that it leads to the same
𝑒𝑒𝑒𝑒
36 damage for a given reference number of load cycles, 𝑛𝑛 , as the real load spectrum
𝑒𝑒𝑒𝑒
37 under the assumption that the damage can be determined on basis of the load cycles
38 from a linear S-N curve with a given slope, 𝑚𝑚. Let the discrete load spectrum be
39 specified by the number of cycles 𝑛𝑛 for the load 𝑆𝑆 , 𝑖𝑖 = 1, 2, … ,𝑛𝑛 . Then the equivalent
𝑖𝑖 𝑖𝑖 𝑆𝑆
40 load can be calculated from the equation

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1⁄𝑚𝑚
𝑛𝑛
𝑚𝑚
𝑆𝑆
∑
𝑛𝑛𝑆𝑆
𝑖𝑖 𝑖𝑖
𝑖𝑖=1
41 𝑆𝑆 =� �
𝑒𝑒𝑒𝑒
𝑛𝑛
𝑒𝑒𝑒𝑒
43 EM Electro Magnetic
44 EMC Electro Magnetic Compatibility
45 NTM90 Normal Turbulence Model, representative value of 90% percentile value of
46 distribution
47 6.2 Wind turbine class
48 Replace paragraph 2 with
49 Class T assumes all wind model parameters to be the same and allows the combination of Vref,T with
50 all turbulence categories. It does not cover all the areas prone to tropical cyclones. The evaluation of
51 the 1-year return period storm wind speed should be done independently of the 50-year return period
52 storm. A site assessment based on Clause 11 is needed, as a minimum assessing that V50 is below Vref
53 of class T (Vref,T), and that V1 is below the classification value.
54 6.3 Wind conditions
55 6.3.1  General
56 Replace paragraphs 3 and 4 with
57 The wind regime for load and safety considerations is divided into the normal wind conditions,
58 which will occur frequently during normal operation of a wind turbine, and the extreme wind
59 conditions that are defined as having a 1-year or 50-year return period.
60 The wind conditions include a constant mean flow combined, in many cases, with either a
61 varying deterministic gust profile or with turbulence. In all cases, an upwards inclination of the
62 mean flow with respect to a horizontal plane of 8° shall be considered. This flow inclination
63 angle shall be assumed to be invariant with height.
64 6.3.2.3  Normal turbulence model (NTM)
65 Replace the clause with
66 For the normal turbulence model, the turbulence standard deviation, σ , shall be defined for the
67 standard wind turbine classes based on the Weibull distribution in equation (10) for the given
68 hub height wind speed.
69 The Weibull distribution for σ1 shall either be applied as a distribution with scale and shape
70 parameters as in equation (11) or by the 90% quantile value in equation (12) :
k

σ

71  (1)
P σ <=σ 1− exp −
( )
W1 0 
C



The return period of the extreme event is independent of the design lifetime of the turbine as the largest value for
the normal failure probability is given for a single year (see Annex K)
The choice of NTM model affects the level of reliability against fatigue failure. Using the Weibull distribution is more
robust for inclusion of non-linear effects, but the resulting fatigue loads have no bias and therefore result in a
lower reliability level in most cases compared to using the 90% quantile value.

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72 where
73 kV0,27 s/m+1,4
( )
hub
CI 0,75V+ 3,3 m / s
74 ( ) (11)
ref hub
75 σ I 0,75V+=bb; 5,6 m/ s (2)
( )
1 ref hub
76 Values for the turbulence standard deviation σ and the turbulence intensity σ V are shown
1 1 hub
77 in Figure 1.
Category A+
Category A
Category B
Category C
0 5 10 15 20 25 30
V (m/s)
hub
IEC
79 Figure 1a – Turbulence standard deviation
0,5
Category A+
Category A
0,4
Category B
Category C
0,3
0,2
0,1
0 10 20 30
V (m/s)
hub
IEC
82 Figure 1b – Turbulence intensity
83 Figure 1 – Turbulence standard deviation and turbulence intensity
84 for the normal turbulence model (NTM90 values)
85 Values for I are given in Table 1.
ref
σ (m/s)
Turbulence intensity
=
=
=
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86 6.3.3.2  Extreme wind speed model (EWM)
87 Replace paragraphs 1 and 2 including eqs.13 and 14 with
88 The EWM shall be a turbulent wind model. The wind model shall be based on the reference
89 wind speed, V , and a fixed turbulence standard deviation, σ . If the wind turbine type is
ref 1
90 designed for a T class reference wind speed, V shall be replaced by V in the extreme
ref ref,T
91 wind speed model while keeping other parameters.
92 Replace footnote 3 with
93 3 The turbulence standard deviation for the turbulent extreme wind model is not related to the normal (NTM) or the
94 extreme turbulence model (ETM).
95 7.4.1 General
96 Add after paragraph 5
97 Serviceability limit states (SLS) consider the function of the structure or one of its components
98 under normal service conditions or the appearance of the structure.
99 Serviceability limit states should be verified with serviceability load levels S1, S2 or S3 as required in
100 relevant IEC 61400 standard or technical specification.
101 For serviceability limit state analyses, S1 is derived from load simulations from the ultimate
102 limit states classified as N (Normal) and for S2 and S3 the same load simulations are used as
103 those used as basis for the fatigue limit state. The partial safety factor for loads shall be: γ =
f
104 1,0 (1)
105 7.4.7 Parked (standstill or idling) (DLC 6.1 to 6.4)
106 Replace paragraphs 2 and 3 with
107 For design load cases, where the wind conditions are defined by EWM, the response shall be
108 estimated using either a full dynamic simulation or a quasi-steady analysis with appropriate
109 corrections for gusts and dynamic response using the formulation in ISO 4354. If slippage in
110 the wind turbine yaw system can occur at the characteristic load, the largest possible
111 unfavourable slippage shall be added to the mean yaw misalignment. If the wind turbine has a
112 yaw system where yaw movement is expected in the extreme wind situations (e.g. free yaw,
113 passive yaw or semi-free yaw), the yaw misalignment will be governed by the turbulent wind
114 direction changes and the turbine yaw dynamic response. Also, if the wind turbine is subject to
115 large yaw movements or change of equilibrium during a wind speed increase from normal
116 operation to the extreme situation, this behaviour shall be included in the analysis.
117 In DLC 6.1, for a wind turbine with an active yaw system, a mean yaw misalignment of ±8° using
118 the turbulent extreme wind model shall be imposed, provided restraint against slippage in the
119 yaw system can be assured.
120 Delete paragraph 5: ‘The partial safety factors for loads …’
121 Replace paragraphs 6 and 7 with
122 In DLC 6.3, the extreme wind with a 1-year return period shall be combined with an extreme
123 yaw misalignment. A mean yaw misalignment of ±20° using the turbulent wind model shall be
124 assumed.
125 If for the case DLC 6.2, yaw misalignment is evaluated using discrete values, the increment in
126 yaw misalignment shall be not more than 10° in the sector of the maximum lift force on the
127 blades.
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128 7.6.1.3 Partial safety factor for consequences of failure and component classes
129 Replace paragraph 1 with
130 A consequence of failure factor, 𝛾𝛾 , is introduced to distinguish between:
𝑛𝑛
131 a. component class 1: used for "fail-safe" components whose failure does not result in the
132 failure of a major part of a wind turbine, for example secondary components and replaceable
133 bearings with monitoring;
134 b. component class 2: used for "safe-life" components whose failures may lead to the failure
135 of a major part of a wind turbine;
136 c. component class 3: used for "safe-life" components whose failure may lead to human
137 injuries e.g. mechanical components that link actuators and brakes to main structural
138 components for the purpose of implementing non-redundant wind turbine protection
139 functions. Regarding blocking devices, see 7.4.9.
140 Add before last paragraph
141 For component class 3, the consequences of failure factor shall be 𝛾𝛾 = 1,2. If the characteristic
𝑛𝑛
142 value of the load response 𝐹𝐹 due to gravity can be calculated for the design situation in
𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑖𝑖𝑔𝑔𝑔𝑔
143 question, and gravity is an unfavourable load, the consequences of failure factor for combined
144 loading from gravity and other sources may have the value
145 𝛾𝛾 = 1,1 + 0,1 ϛ
𝑛𝑛
𝐹𝐹
𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑖𝑖𝑔𝑔𝑔𝑔
| |
1−� � for �𝐹𝐹 �≤ 𝐹𝐹
gravity 𝑘𝑘
𝐹𝐹
146 ϛ =� 𝑘𝑘
| |
0 for �𝐹𝐹 � > 𝐹𝐹
gravity 𝑘𝑘
147 where 𝐹𝐹 is the characteristic load.
𝑘𝑘
149 7.6.2.2 Partial safety factors for loads
150 Add to paragraph starting with ‘When turbulent inflow is used …’
151 When the NTM is represented by a statistical distribution (equation 10 & 11) the characteristic
152 value of the load shall correspond to the same return period as obtained using the 90% quantile
153 value NTM90 (equation 12) except for DLC 1.1.
154 7.6.2.4 Partial safety factors for resistances where recognized design codes are not
155 available
156 Delete footnote 17
157 7.6.2.5 Partial safety factors for materials where recognized design codes are available
158 Replace the clause with
159 Partial safety factors for resistance, γ , shall be applied as given in the recognized design
M
160 codes, see 7.6.1.4. The partial safety factors for the consequences of failure, γ , shall be
n
161 applied additionally as specified in 7.6.1.3.
162 7.6.3.4 Partial material factors where recognized design codes are available
163 Replace the clause with
164 Partial safety factors for resistance, γ , shall be applied as given in the recognized design
M
165 codes, see 7.6.1.4. The partial safety factors for the consequences of failure, γ , shall be
n
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166 applied additionally as specified in 7.6.1.3. Alternatively, the provisions from section 7.6.3.3
167 may be used.
168 Add new clause 7.6.7
169 7.6.7 Evaluation of limit state through load comparison
170 As a simplified approach ultimate limit state analysis may be evaluated through a load
171 comparison with a previously analysed design case. The reference loads shall always serve as
172 the reference for a load comparison.
173 This comparison can be used to assess the suitability of an existing structural design for
174 changed environmental conditions (as per clause 11.10) or for minor changes in turbine design
175 (e.g.controller updates or modification in some other turbine components, e.g. tower). In case
176 of a change of a major component the rest of the structure can be assessed based on a load
177 comparison.
178 The following shall be considered as long as no component specific standards within the IEC
179 61400 series specifies otherwise.
180 For extreme loading, a comparison of contemporaneous loads is not required. All mandatory
181 load cases shall be considered. The sign of the extreme load shall be considered when relevant.
182 For fatigue loading, the comparison may be based on DEL’s. The slope of the S-N curve shall
183 be in alignment with the design analyses of each component.
184 The effect of mean loads shall be included if relevant.
185 An exceedance of up to 5% in extreme loads and 3% in fatigue loads compared to the reference
186 loads is acceptable. In case of exceedances above the given tolerances, all design relevant
187 load signals for the specific component shall be included in the comparison.
188 7.6.7.1  Rotor Blade
189 The comparison shall include a subset of blade sections and load directions representative for
190 the design.
191 If there is no relevant data/information available, at least the blade sections blade root, max
192 chord, blade mid and outer third of the blade length and blade flanges shall be considered.
193 7.6.7.2  Machinery structures and drive train components
194 For fatigue loading, equivalent loads calculated from the LDD or LRD shall be considered
195 additionally for rotating components like gearboxes, bearings, pitch and yaw systems.
196 7.6.7.3  Tower and Foundation

If the mean load has a substantial contribution to the fatigue damage and it is driven by the wind speed, and if the
mean wind distribution differs significantly from
...