IEC 61400-50-1:2022

Wind energy generation systems - Part 50-1: Wind measurement - Application of meteorological mast, nacelle and spinner mounted instruments

IEC 61400-50-1:2022 specifies methods and requirements for the application of instruments to measure wind speed (and related parameters, e.g. wind direction, turbulence intensity). Such measurements are required as an input to some of the evaluation and testing procedures for wind energy and wind turbine technology (e.g. resource evaluation and turbine performance testing) described by other standards in the IEC 61400 series. This document is applicable specifically to the use of wind measurement instruments mounted on meteorological masts, turbine nacelles or turbine spinners which measure the wind at the location at which the instruments are mounted. This document excludes remote sensing devices which measure the wind at some location distant from the location at which the instrument is mounted (e.g. vertical profile or forward facing lidars).

Systèmes de génération d'énergie éolienne - Partie 50-1: Mesurages du vent - Application d'instruments météorologiques montés sur mât, nacelle et nez de rotor

IEC 61400-50-1:2022 spécifie les méthodes et les exigences pour l'application des instruments de mesure de la vitesse du vent (et des paramètres associés, par exemple la direction du vent et l'intensité des turbulences). Ces mesurages sont exigés pour certaines procédures d'évaluation et d'essai de l'énergie éolienne et de la technologie des éoliennes (par exemple, l'évaluation des ressources et les essais de performance des éoliennes) décrites dans d'autres normes de la série IEC 61400. Le présent document s'applique spécifiquement à l'utilisation d'instruments de mesure du vent montés sur des mâts météorologiques, des nacelles d’éolienne ou des nez de rotors d’éolienne qui mesurent le vent à un endroit dans lequel les instruments sont montés. Le présent document exclut les dispositifs de télédétection qui mesurent le vent à un endroit éloigné de celui dans lequel l'instrument est monté (par exemple, les lidars à profil vertical ou orientés vers l'avant)

General Information

• Status: Published
• Publication Date: 15-Nov-2022
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Drafting Committee: MT 12-1 - TC 88/MT 12-1
• Current Stage: PPUB - Publication issued
• Start Date: 25-Nov-2022
• Completion Date: 16-Nov-2022

Relations

• Replaces: IEC 61400-12-2:2013 - Wind turbines - Part 12-2: Power performance of electricity-producing wind turbines based on nacelle anemometry
• Effective Date: 05-Sep-2023
• Replaces: IEC 61400-12-1:2017 - Wind energy generation systems - Part 12-1: Power performance measurements of electricity producing wind turbines
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61400-50-1
®

Edition 1.0 2022-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Wind energy generation systems –
Part 50-1: Wind measurement – Application of meteorological mast, nacelle and
spinner mounted instruments

Systèmes de génération d'énergie éolienne
Partie 50-1: Mesurages du vent – Application d'instruments météorologiques
montés sur mât, nacelle et nez de rotor

IEC 61400-50-1:2022-11(en-fr)

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IEC 61400-50-1

®


Edition 1.0 2022-11




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE
colour

inside










Wind energy generation systems –

Part 50-1: Wind measurement – Application of meteorological mast, nacelle and

spinner mounted instruments



Systèmes de génération d'énergie éolienne

Partie 50-1: Mesurages du vent – Application d'instruments météorologiques


montés sur mât, nacelle et nez de rotor













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 27.180 ISBN 978-2-8322-5937-5




Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 61400-50-1:2022 © IEC 2022
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Symbols, units and abbreviated terms . 11
5 General . 16
6 Classification of cup and sonic anemometry . 16
6.1 General . 16
6.2 Classification classes . 17
6.3 Influence parameter ranges . 17
6.4 Classification of cup and sonic anemometers . 17
6.5 Reporting format . 19
7 Assessment of cup and sonic anemometry . 19
7.1 General . 19
7.2 Measurements of anemometer characteristics . 19
7.2.1 Measurements in a wind tunnel for tilt angular response characteristics
of cup anemometers . 19
7.2.2 Wind tunnel measurements of directional characteristics of cup
anemometers . 21
7.2.3 Wind tunnel measurements of cup anemometer rotor torque
characteristics . 21
7.2.4 Wind tunnel measurements of step responses of cup anemometers . 22
7.2.5 Measurement of temperature induced effects on anemometer
performance . 23
7.2.6 Wind tunnel measurements of directional characteristics of sonic
anemometers . 24
7.3 A cup anemometer classification method based on wind tunnel and
laboratory tests and cup anemometer modelling . 25
7.3.1 Method . 25
7.3.2 Example of a cup anemometer model . 25
7.4 A sonic anemometer classification method based on wind tunnel tests and
sonic anemometer modelling . 32
7.5 Free field comparison measurements . 32
8 Wind tunnel calibration procedure for anemometers . 32
8.1 General requirements . 32
8.2 Requirements for the wind tunnel . 33
8.3 Instrumentation and calibration setup requirements . 35
8.4 Calibration procedure . 35
8.4.1 General procedure for cup and sonic anemometers . 35
8.4.2 Procedure for the calibration of sonic anemometers . 36
8.4.3 Determination of the wind speed at the anemometer position . 36
8.5 Data analysis . 37
8.6 Uncertainty analysis . 37
8.7 Reporting format . 38
8.8 Example uncertainty calculation . 39

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IEC 61400-50-1:2022 © IEC 2022 – 3 –
9 In-situ comparison of anemometers . 42
9.1 General . 42
9.2 Prerequisite . 42
9.3 Analysis method . 42
9.4 Evaluation criteria . 43
10 Mounting of instruments on the meteorological mast . 45
10.1 General . 45
10.2 Single top-mounted anemometer. 46
10.3 Side-by-side top-mounted anemometers . 47
10.4 Side-mounted instruments . 49
10.4.1 General . 49
10.4.2 Tubular meteorological masts . 49
10.4.3 Lattice meteorological masts . 51
10.4.4 Flow distortion correction of side-mounted anemometers . 56
10.5 Lightning protection . 56
10.6 Mounting of other meteorological instruments . 56
10.7 Data acquisition system . 57
11 Uncertainty of wind speed measurement . 57
11.1 Category B uncertainties: Wind speed – Introduction . 57
11.2 Category B uncertainties: Wind speed – Hardware . 57
11.3 Category B uncertainties: Wind speed – Meteorological mast mounted
sensors . 57
11.3.1 General . 57
11.3.2 Pre-calibration . 58
11.3.3 Post-calibration . 58
11.3.4 Classification . 58
11.3.5 Mounting . 59
11.3.6 Lightning finial . 60
11.3.7 Data acquisition . 60
11.4 Category B uncertainties: Method – Cold climate . 60
11.5 Combining uncertainties . 60
11.5.1 General . 60
11.5.2 Combining uncertainties in the wind speed measurement (u ) . 61
V,i
11.5.3 Combining uncertainties in the wind speed measurement from cup or
sonic anemometer (u ) . 61
VS,i
12 Reporting. 61
Annex A (informative) Wind tunnel calibration procedure for wind direction sensors . 63
A.1 General requirements . 63
A.2 Requirements of the wind tunnel . 63
A.3 Instrumentation and calibration setup requirements . 64
A.4 Calibration procedure . 65
A.5 Data analysis . 66
A.6 Uncertainty analysis . 66
A.7 Reporting format . 67
A.8 Example of uncertainty calculation . 68
A.8.1 General . 68
A.8.2 Measurement uncertainties generated by determination of the flow
direction in the wind tunnel . 68

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– 4 – IEC 61400-50-1:2022 © IEC 2022
A.8.3 Uncertainty contribution by uncertainties in the determination of the
geometrical centreline α (wind tunnel centreline) . 68
CL
A.8.4 Contribution by uncertainties in the determination of flow direction α . 68
dir
Annex B (informative) Mast flow distortion correction for lattice masts . 73
Annex C (informative) Nacelle instrument mounting . 76
C.1 General . 76
C.2 Preferred method of anemometer's mounting . 76
C.3 Preferred position of anemometer . 76
Annex D (informative) Spinner anemometers . 78
Bibliography . 79

Figure 1 – Tilt angular response V /V of a cup anemometer as a function of flow
α α=0
angle α compared to cosine response . 21
Figure 2 – Wind tunnel torque measurements Q − Q as a function of angular speed
A F
ω of a cup anemometer rotor at 8 m/s . 22
Figure 3 – Example of bearing friction torque Q as function of temperature for a range
F
of angular speeds ω . 24
Figure 4 – Example of rotor torque coefficient C as a function of speed ratio λ
QA
derived from step responses with κ equal to −5,5 and κ equal to −6,5 . 27
low high
Figure 5 – Classification deviations of example cup anemometer showing a class
1,69A (upper) and a class 6,56B (lower) . 30
Figure 6 – Classification deviations of example cup anemometer showing a class
8,01C (upper) and a class 9,94D (lower) . 31
Figure 7 – Definition of volume for flow uniformity test . 34
Figure 8 – Example valid control anemometer direction sector for a single top-mounted
anemometer on a triangular lattice meteorological mast . 44
Figure 9 – Example valid control anemometer direction sector for a single top-mounted
anemometer on a tubular meteorological mast . 45
Figure 10 – Example of a top-mounted anemometer and requirements for mounting . 47
Figure 11 – Example of alternative top-mounted primary and control anemometers
positioned side-by-side and wind vane and other instruments on the boom . 48
Figure 12 – Iso-speed plot of local flow speed around a cylindrical meteorological mast . 50
Figure 13 – Centreline relative wind speed as a function of distance R from the
d
centre of a tubular meteorological mast and meteorological mast diameter d . 51
Figure 14 – Representation of a three-legged lattice meteorological mast . 51
Figure 15 – Iso-speed plot of local flow speed around a triangular lattice
meteorological mast with a C of 0,5 . 52
T
Figure 16 – Centreline relative wind speed as a function of distance R from the centre
d
of a triangular lattice meteorological mast of leg distance L for various C values . 53
m T
Figure 17 – 3D CFD derived flow distortion for two different wind directions around a
triangular lattice meteorological mast (C = 0,27) . 55
T
Figure A.1 – Example of calibration setup of a wind direction sensor in a wind tunnel . 65
Figure B.1 – Example of mast flow distortion . 73
Figure B.2 – Flow distortion residuals versus wind direction . 75
Figure C.1 – Mounting of anemometer on top of nacelle . 77

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IEC 61400-50-1:2022 © IEC 2022 – 5 –
Table 1 – Influence parameter ranges (10 min averages) of classes A, B, C, D and S . 18
Table 2 – Tilt angle response of example cup anemometer . 28
Table 3 – Friction coefficients of example cup anemometer . 29
Table 4 – Miscellaneous data related to classification of example cup anemometer . 29
Table 5 – Example of evaluation of anemometer calibration uncertainty . 39
Table 6 – Estimation method for C for various types of lattice mast . 54
T
Table A.1 – Uncertainty contributions in wind directions sensor calibration . 71
Table A.2 – Uncertainty contributions and total standard uncertainty in wind direction
sensor calibration . 72

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

WIND ENERGY GENERATION SYSTEMS –

Part 50-1: Wind measurement – Application of meteorological mast,
nacelle and spinner mounted instruments

FOREWORD
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IEC 61400-50-1 has been prepared by IEC technical committee 88: Wind energy generation
systems. It is an International Standard.
This first edition of IEC 61400-50-1 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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IEC 61400-50-1:2022 © IEC 2022 – 7 –
The text of this International Standard is based on the following documents:
Draft Report on voting
88/902/FDIS 88/916/RVD

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.

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– 8 – IEC 61400-50-1:2022 © IEC 2022
INTRODUCTION
This part of IEC 61400 specifies procedures and methods which ensure that wind
measurements using cup or sonic anemometers mounted on meteorological masts or wind
turbine nacelles/spinners are carried out and reported consistently and in accordance with best
practice. This document does not define the purpose or use case of the wind measurements.
However, as this document forms part of the IEC 61400 series of standards, it is anticipated
that the wind measurements carried out in accordance with this standard will be used in relation
to some form of wind energy testing or resource assessment.
The main clauses of this document are not mutually dependent. Therefore, it is possible that a
user will refer to only certain of the main clauses rather than all clauses to adapt this document
to their specific use case. However, the main clauses are presented in a logical sequence that
could be applied in practice.
The technical content of this document could previously be found in IEC 61400-12-1:2017
...