SIST EN IEC 61400-12-6:2022
(Main)Wind energy generation systems - Part 12-6: Measurement based nacelle transfer function of electricity producing wind turbines (IEC 61400-12-6:2022)
Wind energy generation systems - Part 12-6: Measurement based nacelle transfer function of electricity producing wind turbines (IEC 61400-12-6:2022)
This part of IEC 61400-12 specifies a procedure for measuring the nacelle transfer function of
a single electricity-producing, horizontal axis wind turbine, which is not considered to be a small
wind turbine in accordance with IEC 61400-2. It is expected that this document be used when
a valid nacelle transfer function is needed to execute a power performance measurement
according to IEC 61400-12-2.
A wind speed measured on the nacelle or hub of a wind turbine is affected by the turbine rotor
(i.e. speeded up or slowed down wind speed). In IEC 61400-12-1, an anemometer is located on
a meteorological tower that is located between two and four rotor diameters upwind of the test
turbine. This location allows direct measurement of the "free" wind with minimum interference
from the test turbine's rotor. In the procedure of this document, the anemometer is located on
or near the test turbine's nacelle. In this location, the anemometer is measuring a wind speed
that is strongly affected by the test turbine's rotor and the nacelle. The procedure in this
document includes methods for determining and applying appropriate corrections for this
interference. However, note that these corrections inherently increase the measurement
uncertainty compared to a properly configured test conducted in accordance with
IEC 61400-12-1.
This document specifies how to characterise a wind turbine's nacelle transfer function. The
nacelle transfer function is determined by collecting simultaneous measurements of
nacelle-measured wind speed and free stream wind speed (as measured on a meteorological
mast) for a period that is long enough to establish a statistically significant database over a
range of wind speeds and under varying wind and atmospheric conditions. The procedure also
provides guidance on determination of measurement uncertainty including assessment of
uncertainty sources and recommendations for combining them.
Windenergieanlagen - Teil 12-6: Messbasierte Gondelübertragungsfunktion von stromerzeugenden Windkraftanlagen (IEC 61400-12-6:2022)
Systèmes de génération d'énergie éolienne - Partie 12-6: Fonction de transfert de la nacelle fondée sur le mesurage des éoliennes de production d'électricité (IEC 61400-12-6:2022)
IEC 61400-12-6:2022 spécifie une procédure de mesure de la fonction de transfert de la nacelle d’une éolienne simple de production d’électricité à axe horizontal, qui n’est pas considérée comme un petit aérogénérateur selon l’IEC 61400-2. Il est attendu que le présent document soit utilisé lorsqu’il est nécessaire d'employer une fonction de transfert de la nacelle valide pour mesurer la performance de puissance conformément à l’IEC 61400-12-2. Le présent document décrit la façon de déterminer la fonction de transfert de la nacelle d’une éolienne. La fonction de transfert de la nacelle est déterminée en collectant simultanément des valeurs de mesure de la vitesse du vent mesurée à la nacelle et de la vitesse du vent en écoulement libre (mesurée sur un mât météorologique) pendant une période suffisamment longue pour créer une base de données statistiquement significative sur une certaine plage de vitesses du vent et dans des conditions de vent et des conditions atmosphériques variables. Cette procédure fournit également des recommandations relatives à la détermination de l’incertitude de mesure, incluant l’évaluation des sources d’incertitude et des recommandations qui permettent de les combiner.
La présente première édition de l’IEC 61400-12-6 fait partie d'une révision structurelle qui annule et remplace les normes de performance IEC 61400-12-1:2017 et IEC 61400-12-2:2013. Cette révision structurelle ne contient aucune modification technique par rapport à l'IEC 61400‑12‑1:2017 et l'IEC 61400-12‑2:2013. Toutefois, les parties relatives aux mesurages du vent, au mesurage de l'étalonnage du site et à l'évaluation des obstacles et du terrain ont été extraites vers des normes distinctes.
Sistemi za proizvodnjo energije na veter - 12-6. del: Prenosna funkcija na osnovi meritev za vetrne turbine, ki proizvajajo električno energijo (IEC 61400-12-6:2022)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 61400-12-6:2022
01-december-2022
Sistemi za proizvodnjo energije na veter - 12-6. del: Prenosna funkcija na osnovi
meritev za vetrne turbine, ki proizvajajo električno energijo (IEC 61400-12-6:2022)
Wind energy generation systems - Part 12-6: Measurement based nacelle transfer
function of electricity producing wind turbines (IEC 61400-12-6:2022)
Windenergieanlagen - Teil 12-6: Messbasierte Gondelübertragungsfunktion von
stromerzeugenden Windkraftanlagen (IEC 61400-12-6:2022)
Systèmes de génération d'énergie éolienne - Partie 12-6: Fonction de transfert de la
nacelle fondée sur le mesurage des éoliennes de production d'électricité (IEC 61400-12-
6:2022)
Ta slovenski standard je istoveten z: EN IEC 61400-12-6:2022
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
SIST EN IEC 61400-12-6:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 61400-12-6:2022
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SIST EN IEC 61400-12-6:2022
EUROPEAN STANDARD EN IEC 61400-12-6
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2022
ICS 27.180
English Version
Wind energy generation systems - Part 12-6: Measurement
based nacelle transfer function of electricity producing wind
turbines
(IEC 61400-12-6:2022)
Systèmes de génération d'énergie éolienne - Partie 12-6: Windenergieanlagen - Teil 12-6: Messbasierte
Fonction de transfert de la nacelle fondée sur le mesurage Gondelübertragungsfunktion von stromerzeugenden
des éoliennes de production d'électricité Windkraftanlagen
(IEC 61400-12-6:2022) (IEC 61400-12-6:2022)
This European Standard was approved by CENELEC on 2022-10-04. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
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Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61400-12-6:2022 E
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SIST EN IEC 61400-12-6:2022
EN IEC 61400-12-6:2022 (E)
European foreword
The text of document 88/826/CDV, future edition 1 of IEC 61400-12-6, prepared by IEC/TC 88 "Wind
energy generation systems" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 61400-12-6:2022.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-07-04
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2025-10-04
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61400-12-6:2022 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61400-2 NOTE Harmonized as EN 61400-2
2
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SIST EN IEC 61400-12-6:2022
EN IEC 61400-12-6:2022 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60688 - Electrical measuring transducers for EN 60688 -
converting AC and DC electrical quantities
to analogue or digital signals
IEC 61400-12-1 - Wind energy generation systems - Part 12- EN 61400-12-1 -
1: Power performance measurement of
electricity producing wind turbines
IEC 61400-12-2 2022 Wind energy generation systems - Part 12- EN IEC 61400-12-2 2022
2: Power performance of electricity
producing wind turbines based on nacelle
anemometry
IEC 61400-12-3 - Wind energy generation systems - Part 12- EN IEC 61400-12-3 -
3: Power performance - Measurement
based site calibration
IEC 61400-12-5 2022 Wind energy generation systems - Part 12- EN IEC 61400-12-5 2022
5: Power performance - Assessment of
obstacles and terrain
1
IEC 61400-50-1 - Wind energy generation systems - Part 50- EN IEC 61400-50-1 -
1: Wind Measurement - Application of
Meteorological Mast, Nacelle and Spinner
Mounted Instruments
ISO/IEC Guide 98-3 2008 Uncertainty of measurement - Part 3: - -
Guide to the expression of uncertainty in
measurement (GUM:1995)
1
Under preparation. Stage at the time of publication: FprEN IEC 61400-50-1:2022.
3
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SIST EN IEC 61400-12-6:2022
IEC 61400-12-6
®
Edition 1.0 2022-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind energy generation systems –
Part 12-6: Measurement based nacelle transfer function of electricity producing
wind turbines
Systèmes de génération d'énergie éolienne –
Partie 12-6: Fonction de transfert de la nacelle fondée sur le mesurage des
éoliennes de production d'électricité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-5604-6
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® Registered trademark of the International Electrotechnical Commission
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SIST EN IEC 61400-12-6:2022
– 2 – IEC 61400-12-6:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Symbols, units and abbreviated terms . 11
5 Overview of test method . 15
6 Preparation for measurement of nacelle transfer function . 15
6.1 General . 15
6.2 Wind turbine . 15
6.3 Test site . 16
6.3.1 General . 16
6.3.2 Terrain classification . 17
6.4 Test plan . 17
7 Test equipment . 17
7.1 General . 17
7.2 Data acquisition . 18
8 Measurement procedure . 19
8.1 General . 19
8.2 Data system(s) synchronisation . 19
8.3 Data collection . 20
8.4 Data quality check . 20
8.4.1 General . 20
8.4.2 Measured signals are in range and available . 20
8.4.3 Sensors are operating properly . 20
8.4.4 Ensure data acquisition system(s) is(are) operating properly . 21
8.4.5 Sector self-consistency check . 21
8.5 Data rejection . 21
8.6 Data correction . 21
8.7 Database . 22
9 Derived results . 22
9.1 Overview of derived results . 22
9.2 Determination of measured nacelle transfer function . 23
9.3 Data quality check . 24
9.3.1 General . 24
9.3.2 Directional stability check . 24
9.3.3 Self-consistency check for NTF, using the NPC . 25
9.4 Uncertainty analysis . 25
10 Reporting format . 25
Annex A (informative) Nacelle instrument mounting . 29
A.1 General . 29
A.2 Preferred method of anemometer's mounting . 29
A.3 Preferred position of anemometer . 29
Annex B (normative) Evaluation of uncertainty in measurement . 31
B.1 General . 31
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B.2 The measurands . 31
B.3 Uncertainty components. 31
B.4 Wind direction uncertainty . 33
Annex C (normative) Theoretical basis for determining the uncertainty of
measurement using the method of bins . 34
C.1 General . 34
C.2 Propagation of uncertainty through the stages of NTF/NPC measurement . 35
C.3 Category A uncertainties . 38
C.3.1 General . 38
C.3.2 Category A uncertainty in electric power . 38
C.4 Category B uncertainties . 39
C.4.1 General . 39
C.4.2 Category B uncertainties in climatic variations . 40
C.5 Expanded uncertainty . 40
Annex D (normative) NTF uncertainty estimates and calculation . 41
D.1 Methods and assumptions. 41
D.1.1 General . 41
D.1.2 Site calibration . 41
D.1.3 Nacelle transfer function uncertainty component estimates . 43
D.1.4 Nacelle power curve uncertainty component estimates . 45
D.1.5 Wind direction uncertainty . 45
D.1.6 Contribution factors . 47
D.2 Uncertainty example calculations . 48
D.2.1 Example description . 48
D.2.2 Example case – NTF uncertainty . 49
D.2.3 Example case – NPC uncertainty . 49
Annex E (normative) Allowable anemometry instrument types. 51
E.1 General . 51
E.2 Recalibration of sonic anemometers . 51
E.3 Uncertainty of sonic and propeller anemometers . 51
Annex F (informative) Organisation of test, safety and communication . 52
F.1 General . 52
F.2 Responsibility for test . 52
F.3 Safety during test . 52
F.4 Communication . 52
F.5 Prior to test . 52
F.6 During test . 52
F.7 After test . 53
Annex G (informative) NTF flowchart . 54
Bibliography . 55
Figure 1 – Presentation of example data: measured transfer function . 27
Figure A.1 – Mounting of anemometer on top of nacelle . 30
Figure G.1 – NTF flowchart . 54
Table 1 – Example of presentation of a measured power curve based on data from the
meteorological mast, for consistency check . 28
Table B.1 – Uncertainty components in nacelle transfer function evaluation . 32
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Table B.2 – Uncertainty components in nacelle based absolute wind direction . 33
Table C.1 – Example cancellation sources . 36
Table C.2 – List of category A and B uncertainties for NTF . 39
Table C.3 – Expanded uncertainties. 40
Table D.1 – Estimates for uncertainty components from site calibration . 42
Table D.2 – Estimates for uncertainty components from NTF measurement . 44
Table D.3 – Estimates for uncertainty components for wind direction . 46
Table D.4 – Estimates for contribution factors for site calibration . 47
Table D.5 – Estimates for contribution factors for NTF . 48
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SIST EN IEC 61400-12-6:2022
IEC 61400-12-6:2022 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS –
Part 12-6: Measurement based nacelle transfer
function of electricity producing 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
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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.
IEC 61400-12-6 has been prepared by IEC technical committee 88: Wind energy generation
systems. It is an International Standard.
This first edition of IEC 61400-12-6 is part of a structural revision that cancels and replaces the
performance standards IEC 61400-12-1:2017 and IEC 61400-12-2:2013. The structural revision
contains no technical changes with respect to IEC 61400-12-1:2017 and IEC 61400-12-2:2013,
but the parts that relate to wind measurements, measurement of site calibration and assessment
of obstacle and terrain have been extracted into separate standards.
The purpose of the re-structure was to allow the future management and revision of the power
performance standards to be carried out more efficiently in terms of time and cost and to provide
a more logical division of the wind measurement requirements into a series of separate
standards which could be referred to by other use case standards in the IEC 61400 series and
subsequently maintained and developed by appropriate experts.
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SIST EN IEC 61400-12-6:2022
– 6 – IEC 61400-12-6:2022 © IEC 2022
The text of this International Standard is based on the following documents:
Draft Report on voting
88/826/CDV 88/871/RVC
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 International Standard is English.
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.
A list of all parts in the IEC 61400 series, published under the general title Wind energy
generation systems, can be found on the IEC website.
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.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
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IEC 61400-12-6:2022 © IEC 2022 – 7 –
INTRODUCTION
The IEC 61400-12 series consists of the following parts, under the general title Wind energy
generation systems:
IEC 61400-12: Power performance measurements of electricity producing wind
turbines – Overview
IEC 61400-12-1: Power performance measurement of electricity producing wind
turbines
IEC 61400-12-2: Power performance of electricity producing wind turbines based on
nacelle anemometry
IEC 61400-12-3: Power performance – Measurement based site calibration
IEC 61400-12-4: Numerical site calibration
IEC 61400-12-5: Power performance – Assessment of obstacles and terrain
IEC 61400-12-6: Measurement based nacelle transfer function of electricity
producing wind turbines
The purpose of this document is to provide a uniform methodology of measurement, analysis,
and reporting for the determination of a nacelle transfer function of electricity producing wind
turbines utilising nacelle-anemometry methods. This document is intended to be applied only
to horizontal axis wind turbines of sufficient size that the nacelle-mounted anemometer does
not significantly affect the flow through the turbine's rotor and around the nacelle and hence
does not affect the wind turbine's performance. The intent of this document is that the methods
presented herein be utilised when applying the methodology described in IEC 61400-12-2 to
determine the power performance of individual wind turbines. This will ensure that the results
are as consistent, accurate, and reproducible as possible within the current state of the art for
instrumentation and measurement techniques.
This procedure describes how to characterise a wind turbine's nacelle transfer function in terms
of wind speeds measured on a meteorological mast as well as a wind speed measured on the
hub or nacelle of a wind turbine. The anemometer that is placed on the turbine is measuring a
wind speed that is strongly affected by the test turbine's rotor. This procedure includes methods
for determining and applying appropriate corrections for this interference. Such a correction is
termed a nacelle transfer function which relates the wind speed measured on the turbine to a
free-stream wind speed as measured on a meteorological mast. The procedure also provides
guidance on determination of measurement uncertainty including assessment of uncertainty
sources and recommendations for combining them into uncertainties.
Even when anemometers are carefully calibrated in a quality wind tunnel, fluctuations in
magnitude and direction of the wind vector can cause different anemometers to perform
differently in the field. Further, the flow conditions close to a turbine nacelle are complex and
variable. Therefore, special care should be taken in the selection and installation of the
anemometer. These issues are addressed in this document.
This document will benefit those parties interested in power performance testing of wind
turbines using IEC 61400-12-2 as well as parties involved in the installation, planning and
execution of such tests. When and where appropriate, the technically accurate measurement
and analysis techniques recommended in this document should be applied by all parties to
ensure that continuing development and operation of wind turbines is carried out in an
atmosphere of consistent and accurate communication relative to environmental concerns. This
document presents measurement and reporting procedures expected to provide accurate
results that can be replicated by others.
Meanwhile, a user of this document should be aware of differences that arise from large
variations in wind shear and turbulence int
...
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