Wind turbines - Part 1: Design requirements

Amandma A1:2011 je dodatek k standardu SIST EN 61400-1:2006
This part of IEC 61400 specifies essential design requirements to ensure the engineering integrity of wind turbines. Its purpose is to provide an appropriate level of protection against damage from all hazards during the planned lifetime. This standard is concerned with all subsystems of wind turbines such as control and protection mechanisms, internal electrical systems, mechanical systems and support structures. This standard applies to wind turbines of all sizes. For small wind turbines IEC 61400-2 may be applied. This standard should be used together with the appropriate IEC and ISO standards mentioned in Clause 2.

Windenergieanlagen - Teil 1: Auslegungsanforderungen

Eoliennes - Partie 1: Exigences de conception

Vetrne turbine - 1. del: Zahteve za načrtovanje - Dopolnilo A1 (IEC 61400-1:2005/A1:2010)

Amandma A1:2011 je dodatek k standardu SIST EN 61400-1:2006
Ta del IEC 61400 določa osnovne zahteve za načrtovanje, da se zagotovi neoporečnost strojegradnje vetrnih turbin. Njegov namen je zagotoviti primerno raven varstva pred škodo, ki jo lahko  povzročijo vse nevarnosti med načrtovano življenjsko dobo. Ta standard zadeva vse podsisteme vetrnih turbin, kot so mehanizmi nadzora in varovanja, notranji električni sistemi, mehanski sistemi in podporne strukture. Ta standard velja za vetrne turbine vseh velikosti. Za majhne vetrne turbine se lahko uporabi IEC 61400-2. Ta standard se uporablja skupaj s primernimi standardi IEC in ISO, omenjenimi v klavzuli 2.

General Information

Status
Published
Publication Date
18-Nov-2010
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
19-Nov-2010
Completion Date
19-Nov-2010

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SLOVENSKI STANDARD
SIST EN 61400-1:2006/A1:2011
01-januar-2011
9HWUQHWXUELQHGHO=DKWHYH]DQDþUWRYDQMH'RSROQLOR$ ,(&
$
Wind turbines - Part 1: Design requirements (IEC 61400-1:2005/A1:2010)
Windenergieanlagen - Teil 1: Auslegungsanforderungen (IEC 61400-1:2005/A1:2010)
Eoliennes - Partie 1: Exigences de conception (CEI 61400-1:2005/A1:2010)
Ta slovenski standard je istoveten z: EN 61400-1:2005/A1:2010
ICS:
27.180 Sistemi turbin na veter in Wind turbine systems and
drugi alternativni viri energije other alternative sources of
energy
SIST EN 61400-1:2006/A1:2011 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 61400-1:2006/A1:2011
---------------------- Page: 2 ----------------------
SIST EN 61400-1:2006/A1:2011
EUROPEAN STANDARD
EN 61400-1/A1
NORME EUROPÉENNE
November 2010
EUROPÄISCHE NORM
ICS 27.180
English version
Wind turbines -
Part 1: Design requirements
(IEC 61400-1:2005/A1:2010)
Eoliennes - Windenergieanlagen -
Partie 1: Exigences de conception Teil 1: Auslegungsanforderungen
(CEI 61400-1:2005/A1:2010) (IEC 61400-1:2005/A1:2010)

This amendment A1 modifies the European Standard EN 61400-1:2005; it was approved by CENELEC on

2010-11-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which

stipulate the conditions for giving this amendment 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 amendment 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, Croatia, 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
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61400-1:2005/A1:2010 E
---------------------- Page: 3 ----------------------
SIST EN 61400-1:2006/A1:2011
EN 61400-1:2005/A1:2010 - 2 -
Foreword

The text of document 88/374/FDIS, future amendment 1 to IEC 61400-1:2005, prepared by IEC TC 88,

Wind turbines, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as

amendment A1 to EN 61400-1:2005 on 2010-11-01.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent

rights.
The following dates were fixed:
– latest date by which the amendment has to be
implemented at national level by publication of
(dop) 2011-08-01
an identical national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2013-11-01
with the amendment have to be withdrawn
__________
Endorsement notice

The text of amendment 1:2010 to the International Standard IEC 61400-1:2005 was approved by

CENELEC as an amendment to the European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60034 series NOTE Harmonized in EN 60034 series (partially modified).
IEC 60146 series NOTE Harmonized in EN 60146 series (not modified).
IEC 60269 series NOTE Harmonized in EN 60269 series (partially modified).
IEC 60439 series NOTE Harmonized in EN 60439 series (partially modified).
IEC 60446:2007 NOTE Harmonized as EN 60446:2007 (not modified).
IEC 60529:1989 NOTE Harmonized as EN 60529:1991 (not modified).
IEC 60617 NOTE Harmonized in EN 60617 series (not modified).
IEC 60898 NOTE Harmonized as EN 60898.
IEC 61310-1:2007 NOTE Harmonized as EN 61310-1:2008 (not modified).
IEC 61310-2:2008 NOTE Harmonized as EN 61310-2:2008 (not modified).
ISO 9001 NOTE Harmonized as EN ISO 9001.
__________
---------------------- Page: 4 ----------------------
SIST EN 61400-1:2006/A1:2011
- 3 - EN 61400-1:2005/A1:2010
Replace Annex ZA of EN 61400-1:2005 with the following:
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 60204-1 - Safety of machinery - Electrical equipment of EN 60204-1 -
machines -
Part 1: General requirements
IEC 60204-11 - Safety of machinery - Electrical equipment of EN 60204-11 -
machines -
Part 11: Requirements for HV equipment for
voltages above 1 000 V a.c. or 1 500 V d.c.
and not exceeding 36 kV
IEC 60364 Series Low-voltage electrical installations EN 60364 Series
IEC 60364-5-54 - Low-voltage electrical installations - HD 60364-5-54 -
Part 5-54: Selection and erection of electrical
equipment - Earthing arrangements and
protective conductors
IEC 60721-2-1 - Classification of environmental conditions - HD 478.2.1 S1 -
Part 2-1: Environmental conditions appearing
in nature - Temperature and humidity
IEC 61000-6-1 - Electromagnetic compatibility (EMC) - EN 61000-6-1 -
Part 6-1: Generic standards - Immunity for
residential, commercial and light-industrial
environments
IEC 61000-6-2 - Electromagnetic compatibility (EMC) - EN 61000-6-2 -
Part 6-2: Generic standards - Immunity for
industrial environments
IEC 61000-6-4 - Electromagnetic compatibility (EMC) - EN 61000-6-4 -
Part 6-4: Generic standards - Emission
standard for industrial environments
IEC 61400-2 - Wind turbine - EN 61400-2 -
Part 2: Design requirements for small wind
turbines
IEC 61400-21 - Wind turbines - EN 61400-21 -
Part 21: Measurement and assessment of
power quality characteristics of grid connected
wind turbines
At draft stage
HD 478.2.1 S1 includes A1 to IEC 60721-2-1.
---------------------- Page: 5 ----------------------
SIST EN 61400-1:2006/A1:2011
EN 61400-1:2005/A1:2010 - 4 -
Publication Year Title EN/HD Year
IEC 61400-24 - Wind turbines - EN 61400-24 -
Part 24: Lightning protection
IEC 62305-3 - Protection against lightning - EN 62305-3 -
Part 3: Physical damages to structures and
life hazard
IEC 62305-4 - Protection against lightning - EN 62305-4 -
Part 4: Electrical and electronic systems within
structures
ISO 76 2006 Rolling bearings - Static load ratings - -
ISO 281 - Rolling bearings - Dynamic load ratings and - -
rating life
ISO 2394 1998 General principles on reliability for structures - -
ISO 2533 1975 Standard atmosphere - -
ISO 4354 - Wind actions on structures - -
ISO 6336-2 - Calculation of load capacity of spur and helical - -
gears -
Part 2: Calculation of surface durability
(pitting)
ISO 6336-3 2006 Calculation of load capacity of spur and helical - -
gears -
Part 3: Calculation of tooth bending strength
ISO 81400-4 - Wind turbines - - -
Part 4: Design and specification of gearboxes
At draft stage.
At draft stage.
---------------------- Page: 6 ----------------------
SIST EN 61400-1:2006/A1:2011
IEC 61400-1
Edition 3.0 2010-10
INTERNATIONAL
STANDARD
AMENDMENT 1
Wind turbines –
Part 1: Design requirements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 27.180 ISBN 978-2-88912-201-1
® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 7 ----------------------
SIST EN 61400-1:2006/A1:2011
– 2 – 61400-1 Amend.1 © IEC:2010(E)
FOREWORD
This amendment has been prepared by IEC technical committee 88: Wind turbines.
The text of this amendment is based on the following documents:
FDIS Report on voting
88/374/FDIS 88/378/RVD

Full information on the voting for the approval of this amendment can be found in the report

on voting indicated in the above table.

The committee has decided that the contents of this amendment and the base publication will

remain unchanged until the stability 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.
A bilingual version may be issued at a later date.
_____________
---------------------- Page: 8 ----------------------
SIST EN 61400-1:2006/A1:2011
61400-1 Amend.1 © IEC:2010(E) – 3 –
2 Normative references
Replace the existing list of normative references by the following new list:

IEC 60204-1, Safety of machinery – Electrical equipment of machines – Part 1: General

requirements
IEC 60204-11, Safety of machinery – Electrical equipment of machines – Part 11:

Requirements for HV equipment for voltages above 1 000 V a.c. or 1 500 V d.c. and not

exceeding 36 kV
IEC 60364 (all parts), Low-voltage electrical installations

IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of

electrical equipment – Earthing arrangements, protective conductors and protective bonding

conductors

IEC 60721-2-1, Classification of environmental conditions – Part 2: Environmental conditions

appearing in nature – Temperature and humidity

IEC 61000-6-1, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards –

Immunity for residential, commercial and light-industrial environments

IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –

Immunity for industrial environments

IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards –

Emission standard for industrial environments
IEC 61400-2, Wind turbines – Part 2: Design requirements for small wind turbines

IEC 61400-21, Wind turbines – Part 21: Measurement and assessment of power quality

characteristics of grid connected wind turbines
IEC 61400-24, Wind turbines – Part 24: Lightning protection

IEC 62305-3, Protection against lightning – Part 3: Physical damage to structures and life

hazard

IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within

structures
ISO 76:2006, Rolling bearings – Static load ratings
ISO 281, Rolling bearings – Dynamic load ratings and rating life
ISO 2394:1998, General principles on reliability for structures
ISO 2533:1975, Standard atmosphere
ISO 4354, Wind actions on structures

ISO 6336-2, Calculation of load capacity of spur and helical gears – Part 2: Calculation of

surface durability (pitting)
---------------------- Page: 9 ----------------------
SIST EN 61400-1:2006/A1:2011
– 4 – 61400-1 Amend.1 © IEC:2010(E)

ISO 6336-3:2006, Calculation of load capacity of spur and helical gears – Part 3: Calculation

of tooth bending strength
ISO 81400-4, Wind turbines – Part 4: Design and specification of gearboxes
3 Terms and definitions
3.26 – limit state
Replace ISO 2394 by 2.2.9 of ISO 2394.
3.55 – ultimate limit state
Replace ISO 2394 by 2.2.10 of ISO 2394.
4 Symbols and abbreviated terms
4.1 Symbols and units

Switch the definitions of σ and σ . The vertical wind velocity standard deviation should be σ ,

2 3 3
not σ .
6 External conditions
6.3.1.3 Normal turbulence model (NTM)
Replace the existing Figures 1a and 1b by the following new figures:
Category A
4,5
Category B
Category C
3,5
2,5
1,5
0,5
0 5 10 15 20 25 30
V (m/s)
IEC 2236/10
hub
Figure 1a –Turbulence standard deviation for the normal turbulence model (NTM)
σ (m/s)
---------------------- Page: 10 ----------------------
SIST EN 61400-1:2006/A1:2011
61400-1 Amend.1 © IEC:2010(E) – 5 –
0,5
Category A
Category B
0,4
Category C
0,3
0,2
0,1
0 5 10 15 20 25 30
V (m/s)
hub
IEC 2237/10
Figure 1b – Turbulence intensity for the normal turbulence model (NTM)
6.3.2.6 Extreme wind shear (EWS)

Replace the number 2,5 in equations (26) and (27) to 2,5 [m/s]. (The number 2,5 in equations

(26) and (27) is not dimensionless.)
7 Structural design
7.4.2 Power production plus occurrence of fault or loss of electrical network
connection (DLC 2.1 – 2.4)
paragraph, the following new text:
Add, as 2

As an alternative to the specification of DLC 2.3 above and in Table 2, DLC 2.3 may instead

be considered as a normal event (i.e. a partial safety factor for load of 1,35) to be analyzed

using stochastic wind simulations (NTM - V in hub out

electrical system fault (including loss of electrical network connection). In this case, 12

response simulations shall be carried out for each considered mean wind speed. For each

response simulation, the extreme response after the electrical fault has occurred is sampled.

The fault must be introduced after the effect of initial conditions has become negligible. For

each mean wind speed, a nominal extreme response is evaluated as the mean of the 12

sampled extreme responses plus three times the standard deviation of the 12 samples. The

characteristic response value for DLC 2.3 is determined as the extreme value among the

nominal extreme responses.
7.5 Load calculations
Add, after second paragraph, the following new text:

When turbulent winds are used for dynamic simulations, attention should be given to the grid

resolution regarding the spatial and time resolution.
—————————

Concerning the spatial resolution, the maximum distance between adjacent points should be smaller than 25 %

of Λ1 (Equation (5)) and no larger than 15 % of the rotor diameter. This distance is meant to be the diagonal

distance between points in each grid cell defined by four points. In the case of a non-uniform grid, an average

value over the rotor surface of the distance between grid points can be considered as the representative spatial

resolution, but this distance should always decrease towards the blade tip.
Turbulence intensity
---------------------- Page: 11 ----------------------
SIST EN 61400-1:2006/A1:2011
– 6 – 61400-1 Amend.1 © IEC:2010(E)
Replace the last paragraph by the following new text:

Ultimate load components may also be combined in a conservative manner assuming the

extreme component values occur simultaneously. In case this option is pursued, both

minimum and maximum extreme component values shall be applied in all possible
combinations to avoid introducing non-conservatism.

Guidance for the derivation of extreme design loads from contemporaneous loads taken from

a number of stochastic realisations is given in Annex H.
7.6.1.2 Partial safety factor for consequence of failure and component classes
Add, after the bullets defining the component classes, the following new text:

The consequences of failure factor shall be included in the test load when performing tests

as for example full scale blade testing.
7.6.2 Ultimate strength analysis
Replace equation (31) by the following new equation:
1 1
γ F ≤ ⋅ f (31)
f k k
γ γ
n m
Add the following new paragraph after equation (31):

Note that γ is a consequence of failure factor and shall not be treated as a safety factor on

materials.

Delete the last sentence in 5 paragraph (“For guidance see Annex F”) and insert, after the

5 paragraph, the following two paragraphs:

Data used in extrapolation methods shall be extracted from time series of turbine simulations

of at least 10 min in length over the operating range of the turbine for DLC 1.1. A minimum of

15 simulations is required for each wind speed from (V – 2 m/s) to cut-out and six

rated

simulations are required for each wind speed below (V – 2 m/s). When extracting data,

rated

the designer must consider the effect of independence between peaks on the extrapolation

and minimize dependence when possible. The designer shall aggregate data and probability

distributions to form a consistent long-term distribution. To ensure stable estimation of long-

term loads, a convergence criterion shall be applied to a probability fractile less than the

mode of the data for either the short-term or long-term exceedance distributions. For

guidance, see Annex F.

The characteristic value for blade root in-plane and out-of-plane moments and tip deflection

may be determined by a simplified procedure . The characteristic value may then be

determined by calculating the mean of the extremes for each 10-min bin and using the largest

value, multiplied by an extrapolation factor of 1,5, while maintaining the partial load factor for

statistical load extrapolation, see Table 3.
—————————

This approach is considered conservative for 3-bladed upwind wind turbines. Caution should be exercised for

other wind turbine concepts.
---------------------- Page: 12 ----------------------
SIST EN 61400-1:2006/A1:2011
61400-1 Amend.1 © IEC:2010(E) – 7 –
7.6.2.1 Partial safety factor for loads

Replace the existing formula in the footnote of Table 3 by the following new formula:

⎧ F
gravity
1− ; F ≤ F
gravity k
ς = k
0; F > F
⎪ gravity k
Add the following new text after Table 3:

The approach in 7.6.1.1, where the partial safety factor for loads is applied to the load

response, assumes that a proper representation of the dynamic response is of prime concern.

For foundations or where a proper representation of non-linear material behaviour or

geometrical non-linearities or both are of primary concern, the design load response S shall

be obtained from a structural analysis for the combination of the design loads F , where the

design load is obtained by multiplication of the characteristic loads F by the specified partial

load factor γ for favourable and unfavourable loads,
F = γ F
d f k

The load responses in the tower at the interface (shear forces and bending moments) factored

with γ from Table 3 shall be applied as boundary conditions.

For gravity foundations, the limit states considering overall stability (rigid body motion with no

failure in soil) and bearing capacity of soil and foundation shall be regarded and calculated

according to a recognized standard. In general, a partial safety factor of γ = 1,1 for

unfavourable permanent loads and γ = 0,9 for favourable permanent loads shall be applied

for foundation load, backfilling and buoyancy. If it can be demonstrated by respective quality

management and surveillance that the foundation material densities specified in the design

documentation are met on site, a partial safety factor for permanent foundation load γ = 1,0

can be used for the limit states regarding bearing capacity of soil and foundation. If buoyancy

is calculated equal to a terrain water level, a partial safety factor for buoyancy γ = 1,0 can be

applied.

Alternatively, the check of capacity of soil and foundation can be based on a partial safety

factor γ = 1,0 for both favourable and unfavourable permanent loads and the check of overall

stability can be based on a partial safety factor of γ = 1,1 for unfavourable permanent loads

and γ = 0,9 for favourable permanent loads, using in all cases conservative estimates of

weights or densities defined as 5 % / 95 % fractiles. The lower fractile is to be used when the

load is favourable. Otherwise, the upper fractile is to be used.
7.6.5 Critical deflection analysis
Replace the existing text by the following new text:
7.6.5.1 General

It shall be verified that no deflections affecting structural integrity occur in the design

conditions detailed in Table 2.

The maximum elastic deflection in the unfavourable direction shall be determined for the load

cases detailed in Table 2 using the characteristic loads. The resulting deflection is then

multiplied by the combined partial safety factor for loads, materials and consequences of

failure.
• Partial safety factor for loads
The values of γ shall be chosen from Table 3.
---------------------- Page: 13 ----------------------
SIST EN 61400-1:2006/A1:2011
– 8 – 61400-1 Amend.1 © IEC:2010(E)
• Partial safety factor for the elastic properties of materials

The value of γ shall be 1,1 except when the elastic properties of the component in question

have been determined by testing and monitoring in which case it may be reduced. Particular

attention shall be paid to geometrical uncertainties and the accuracy of the deflection

calculation method.
• Partial safety factor for consequences of failure
Component class 1: γ = 1,0
Component class 2: γ = 1,0
Component class 3: γ = 1,3.

The elastic deflection shall then be added to the un-deflected position in the most

unfavourable direction and the resulting position compared to the requirement for non-

interference.
7.6.5.2 Blade (tip) deflection

One of the most important considerations is to verify that no mechanical interference between

blade and tower will occur.

In general, blade deflections have to be calculated for the ultimate load cases as well as for

the fatigue load cases. The deflections caused by the ultimate load cases can be calculated

based on beam models, FE models or the like. All relevant load cases from Table 2 have to

be taken into account with the relevant partial load safety factors.

Moreover, for load case 1.1 extrapolation of tip deflection is mandatory according to 7.4.1.

Here direct dynamic deflection analysis can be used. The exceedance probability in the most

unfavourable direction shall be the same for the characteristic deflection as for the

characteristic load. The characteristic deflection is then to be multiplied by the combined

safety factor for loads, materials and consequences of failure and be added to the un-

deflected position in the most unfavourable direction and the resulting position compared to

the requirement for non-interference.
9 Mechanical systems
9.4 Main gearbox
Replace the existing text by the following new text:

The main gearbox shall be designed according to ISO 81400-4, until a similar document is

published in the IEC 61400 series.
9.5 Yaw system
Replace the second paragraph by the following new text:
Any motors shall comply with relevant parts of Clause 10.

Non-redundant parts of the gear system such as the final yaw gear shall be considered as

component class 2. When multiple yaw drives ensure sufficient redundancy in the yaw gear

system, and easy replacement is possible, the reduction gearbox and the final drive pinion

may be considered to be in component class 1.

The safety against pitting shall be determined in accordance with ISO 6336-2. The application

of the upper limit curve (1) for life factor Z , which allows limited pitting, is permissible.

Sufficient tooth bending strength shall be proven in accordance with ISO 6336-3. The reverse

---------------------- Page: 14 ----------------------
SIST EN 61400-1:2006/A1:2011
61400-1 Amend.1 © IEC:2010(E) – 9 –

bending loads on gear teeth shall be considered in accordance with ISO 6336-3 Annex B.

Minimum values for S and S are specified in Table 5. These values must be achieved by

F H

using characteristic loads F Hence they include the partial safety factor for consequences, γ ,

k n
materials, γ and loads, γ .
m f
Table 5 – Minimum required safety factor S and S for the yaw gear system
H F
Component class 1 Component class 2
Surface durability (pitting) s ≥ 1,0 s ≥ 1,1
H H
Tooth bending fatigue strength
s ≥ 1,1 s ≥ 1,25
F F
Static bending strength s ≥ 1,0 s ≥ 1,2
F F

Lower safety factors may be applicable in cases where efficient monitoring is implemented. If

safety factors below 1,0 are applied, then the maintenance manual must reflect anticipated

replacement intervals.
10 Electrical system
10.5 Earth system
Replace, in the first paragraph, IEC 61024-1 by IEC 62305-3.
10.6 Lightning protection
Replace IEC 61024-1 by IEC 62305-3.
10.9 Protection against lightning electromagnetic fields
Replace, in the first paragraph, IEC 61312-1 by IEC 62305-4.
11 Assessment of a wind turbine for site-specific conditions
11.2 Assessment of the topographical complexity of a site
Replace the text of this subclause by the following new text:

The complexity of the site is characterised by the slope of the terrain and variations of the

terrain topography from a plane.

To obtain the slope of the terrain, planes are defined that fit the terrain within specific

distances and sector amplitudes for all wind direction sectors around the wind turbine and

pass through the tower base. The slope, used in Table 4, denotes the slopes of the different

mean lines of sectors passing through the tower bases and contained in the fitted planes.

Accordingly, the terrain variation from the fitted plane denotes the distance, along a vertical

line, between the fitted plane and the terrain at the surface points.
---------------------- Page: 15 ----------------------
SIST EN 61400-1:2006/A1:2011
– 10 – 61400-1 Amend.1 © IEC:2010(E)
Table 4 – Terrain complexity indicators
Maximum terrain
Distance range from Maximum slope of fitted
Sector amplitude
wind turbine plane
variation
< 5 z 360º < 0,3 z
hub hub
30º < 10º
< 10 z < 0,6 z
hub hub
30º
< 20 z < 1,2 z
hub hub

The resolution of surface grids used for terrain complexity assessment must not exceed the

smallest of 1,5 z and 100 m.
hub

The site shall be considered complex, if 15 % of the energy in the wind comes from sectors

that fail to conform to the criteria in Table 4 and homogeneous, if less than 5 % of the energy

in the wind comes from sectors that fail to conform.

A complexity index i is defined, such that i = 0 when less than 5 % of the energy comes

c c

from complex sectors, and i = 1 when more than 15 % of the energy comes from complex

sectors. In between, i varies linearly.
11.4 Assessment of wake effects from neighbouring wind turbines
Add the following new text after the 3rd paragraph:

Generally, the effective turbulence for fatigue and various ultimate loads cannot be assumed

to be the same.
Delete the 4 paragraph to the end of the subclause.
11.9 Assessment of structural integrity by reference to wind data
Replace the existing footnote 18 by the following new footnote:

The effect of complex terrain may be included by additional multiplication with a turbulence

structure correction parameter C defined as
2 2
1+()σˆ / σˆ +()σˆ / σˆ
2 1 3 1
C =
1,375

where ratios of the estimated standard deviations, σˆ , correspond to hub height values. Where

there are no site data for the components of turbulence and the terrain is complex, results of

modelling or C = 1+0,15 i , where i is the complexity index defined in Subclause 11.2, may

CT c c
be used.
Replace the 5 paragraph to the end of the subclause by the following new text:

An adequate assessment of wake effects can be performed by verifying that the turbulence

standard deviation σ from the normal turbulence model is greater or equal to the estimated

90 % fractile of the turbulence standard deviation (including both ambient and wake

—————————

3 The check criteria is considered fulfilled if the requisite fails over a surface less than 5 z .

hub

This approach can also be used for the assessment of sector-wise varying turbulence, alone or in combination

with wake turbulence. The standard deviation ˆ of σˆ may be determined as the average of the sector-wise

values.
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SIST EN 61400-1:2006/A1:2011
61400-1 Amend.1 © IEC:2010(E) – 11 –

turbulence) between the wind speeds 0,2 V and 0,4 V (or when the turbine properties are

ref ref
known, between 0,6 V and V ), i.e.:
r out
σ≥⋅I V
(35)
1 eff hub
Guidance for calculating I can be found in Annex D.
eff

Furthermore, it shall be demonstrated that the site specific horizontal shear due to partial

wakes does not exceed EWS in 6.3.2.6 and that the site specific extreme turbulence ,

including the wake effects, does not exceed the ETM model in 6.3.2.3. For determination of

the site specific turbulence, the site specific conditions, the frequency of the wake situations

and wind farm layout shall be accounted for.

11.10 Assessment of structural integrity by load calculations with reference to site

specific conditions
Replace the 2 paragraph to the end of the subclause by the following new text:

Where there are no site data for the components of turbulence and the terrain is complex, it

shall be assumed that the lateral and upward turbulence standard deviations relative to the

longitudinal component are equal to 1,0 and 0,7, respectively.
...

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