SIST EN IEC 61400-21-1:2019
(Main)Wind energy generation systems - Part 21-1: Measurement and assessment of electrical characteristics - Wind turbines (IEC 61400-21-1:2019)
Wind energy generation systems - Part 21-1: Measurement and assessment of electrical characteristics - Wind turbines (IEC 61400-21-1:2019)
IEC 61400-21-1:2019 includes:
· definition and specification of the quantities to be determined for characterizing the electrical characteristics of a grid-connected wind turbine;
· measurement procedures for quantifying the electrical characteristics;
· procedures for assessing compliance with electrical connection requirements, including estimation of the power quality expected from the wind turbine type when deployed at a specific site.
The measurement procedures are valid for single wind turbines with a three-phase grid connection. The measurement procedures are valid for any size of wind turbine, though this part of IEC 61400 only requires wind turbine types intended for connection to an electricity supply network to be tested and characterized as specified in this part of IEC 61400.
This first edition cancels and replaces the second edition of 61400-21 published in 2008. This edition includes the following new items with respect to 61400-21:
a) frequency control measurement;
b) updated reactive power control and capability measurement, including voltage and cos φ control;
c) inertia control response measurement;
d) overvoltage ride through test procedure;
e) updated undervoltage ride through test procedure based on Wind Turbine capability;
f) new methods for the harmonic assessment.
Windenergieerzeugungsanlagen - Teil 21-1: Messung und Bewertung der elektrischen Kennwerte - Windenergieanlagen (IEC 61400-21-1:2019)
Systèmes de génération d'énergie éolienne - Partie 21-1: Mesurage et évaluation des caractéristiques électriques - Éoliennes (IEC 61400-21-1:2019)
l'IEC 61400-21-1:2019 comprend:
· la définition et la spécification des grandeurs à déterminer pour caractériser les caractéristiques électriques d'une éolienne connectée à un réseau;
· les procédures de mesure pour quantifier les caractéristiques électriques;
· les procédures pour évaluer la conformité aux exigences de raccordement électrique, y compris l'estimation de la qualité de puissance attendue d'un type d'éolienne, une fois déployée sur un site spécifique.
Les procédures de mesure sont valables pour les éoliennes individuelles avec un raccordement triphasé au réseau. Les procédures de mesure sont valables pour n'importe quelle taille d'éolienne; toutefois, la présente partie de l'IEC 61400 exige uniquement des types d'éoliennes prévues pour le raccordement à un réseau d'alimentation électrique, qui sont donc à soumettre aux essais et à caractériser comme spécifié dans la présente partie de l'IEC 61400.
Cette première édition annule et remplace la deuxième édition de l'IEC 61400-21 parue en 2008.
Cette édition inclut les nouveaux éléments suivants par rapport à l'IEC 61400-21:
a) mesure de contrôle de fréquence;
b) contrôle actualisé de la puissance réactive et de la mesure de la capacité, y compris le contrôle de la tension et contrôle du cos φ;
c) mesure de la réponse du contrôle d'inertie;
d) procédure d'essai du passage de surtension;
e) procédure d'essai du maintien de l'alimentation en sous-tension en fonction de la capacité des éoliennes actualisée;
f) nouvelles méthodes pour l'évaluation de l'harmonique.
Sistemi za proizvodnjo energije na veter - 21-1. del: Merjenje in ocenjevanje električnih karakteristik - Vetrne turbine (IEC 61400-21-1:2019)
Ta del standarda IEC 61400 vključuje:
• opredelitev in specifikacijo količin, ki jih je treba določiti za opis električnih karakteristik vetrne turbine, povezane z omrežjem;
• merilne postopke za količinsko opredelitev električnih karakteristik;
• postopke za oceno skladnosti z zahtevami za električno povezavo, vključno z oceno pričakovane kakovosti električne energije glede na vrsto vetrne turbine, ko je nameščena na določenem mestu.
Postopki merjenja veljajo za enojne vetrne turbine s trifaznim omrežnim priključkom. Postopki merjenja veljajo za poljubno velikost vetrne turbine, čeprav ta del standarda IEC 61400 zahteva le preskus in karakterizacijo vetrnih turbin v skladu s tem delom standarda IEC 61400, ki so namenjene za povezavo z električnim omrežjem.
Izmerjene karakteristike veljajo za specifično konfiguracijo in način delovanja ocenjevane platforme vetrnih turbin. Če izmerjena lastnost temelji na regulacijskih parametrih in se na podlagi spremembe te lastnosti spremeni delovanje vetrne turbine, je to navedeno v poročilu o preskusu. Primer: Zaščita omrežja, pri kateri raven odklopa temelji na parametru in preskus preveri zgolj pravilno delovanje zaščite, ne pa specifične ravni.
Postopki merjenja so zasnovani tako, da so čim manj odvisni od mesta namestitve, tako da je električne karakteristike, izmerjene na primer na preskusnem mestu, mogoče obravnavati kot reprezentativne tudi za druga mesta.
Ta dokument je namenjen preskušanju vetrnih turbin; vsi postopki, meritve in preskusi v zvezi z vetrnimi elektrarnami so zajeti v standardu IEC 61400-21-2.
Postopki za oceno električnih karakteristik veljajo za vetrne turbine s priključkom na PCC v elektroenergetskih sistemih z nespremenljivo frekvenco omrežja.
OPOMBA:
V tem dokumentu se uporabljajo naslednji izrazi za napetost v omrežju:
– nizka napetost (LV) označuje Un ≤ 1 kV;
– srednja napetost (MV) označuje 1 kV < Un ≤ 35 kV;
– visoka napetost (HV) označuje 35 kV < Un ≤ 220 kV;
– zelo visoka napetost (EHV) označuje Un > 220 kV.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2019
Sistemi za proizvodnjo energije na veter - 21-1. del: Merjenje in ocenjevanje
električnih karakteristik - Vetrne turbine (IEC 61400-21-1:2019)
Wind energy generation systems - Part 21-1: Measurement and assessment of electrical
characteristics - Wind turbines (IEC 61400-21-1:2019)
Windenergieerzeugungsanlagen - Teil 21-1: Messung und Bewertung der elektrischen
Kennwerte - Windenergieanlagen (IEC 61400-21-1:2019)
Systèmes de génération d'énergie éolienne - Partie 21-1: Mesurage et évaluation des
caractéristiques électriques - Éoliennes (IEC 61400-21-1:2019)
Ta slovenski standard je istoveten z: EN IEC 61400-21-1:2019
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 61400-21-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2019
ICS 27.180
English Version
Wind energy generation systems - Part 21-1: Measurement and
assessment of electrical characteristics - Wind turbines
(IEC 61400-21-1:2019)
Systèmes de génération d'énergie éolienne - Partie 21-1: Windenergieerzeugungsanlagen - Teil 21-1: Messung und
Mesurage et évaluation des caractéristiques électriques - Bewertung der elektrischen Kennwerte -
Éoliennes Windenergieanlagen
(IEC 61400-21-1:2019) (IEC 61400-21-1:2019)
This European Standard was approved by CENELEC on 2019-06-24. 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,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey 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
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61400-21-1:2019 E
European foreword
The text of document 88/711/FDIS, future edition 1 of IEC 61400-21-1, prepared by IEC/TC 88 "Wind energy
generation systems" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national level by (dop) 2020-03-24
publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-06-24
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.
Endorsement notice
The text of the International Standard IEC 61400-21-1:2019 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 61400-27-1:2015 NOTE Harmonized as EN 61400-27-1:2015 (not modified)
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 61000-3-2 2014 Electromagnetic compatibility (EMC) - Part 3-2: Limits EN 61000-3-2 2014
- Limits for harmonic current emissions (equipment
input current ≤ 16 A per phase)
IEC 61000-3-3 - Electromagnetic compatibility (EMC) - Part 3-3: Limits EN 61000-3-3 -
- Limitation of voltage changes, voltage fluctuations
and flicker in public low-voltage supply systems, for
equipment with rated current < 16 A per phase and
not subject to conditional connection
IEC 61000-4-7 2002 Electromagnetic compatibility (EMC) - Part 4-7: EN 61000-4-7 2002
Testing and measurement techniques - General
guide on harmonics and interharmonics
measurements and instrumentation, for power supply
systems and equipment connected thereto
+ A1 2008 + A1 2009
IEC 61000-4-15 2010 Electromagnetic compatibility (EMC) - Part 4-15: EN 61000-4-15 2011
Testing and measurement techniques - Flickermeter -
Functional and design specifications
IEC 61000-4-30 - Electromagnetic compatibility (EMC) - Part 4-30: EN 61000-4-30 -
Testing and measurement techniques - Power quality
measurement methods
IEC 62008 - Performance characteristics and calibration methods EN 62008 -
for digital data acquisition systems and relevant
software
IEC/TR 61000- - Electromagnetic compatibility (EMC) - Part 3-6: Limits - -
3-6 - Assessment of emission limits for the connection of
distorting installations to MV, HV and EHV power
systems
IEC/TR 61000- - Electromagnetic compatibility (EMC) - Part 3-7: Limits - -
3-7:2008 - Assessment of emission limits for the connection of
fluctuating installations to MV, HV and EHV power
systems
IEC/TR 61000- - Electromagnetic compatibility (EMC) - Part 3-14: - -
3-14 Assessment of emission limits for harmonics,
interharmonics, voltage fluctuations and unbalance
for the connection of disturbing installations to LV
power systems
IEC/TR 61869- 2012 Instrument transformers - The use of instrument - -
103 transformers for power quality measurement
IEC 61400-21-1 ®
Edition 1.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind energy generation systems –
Part 21-1: Measurement and assessment of electrical characteristics – Wind
turbines
Systèmes de génération d'énergie éolienne –
Partie 21-1: Mesurage et évaluation des caractéristiques électriques – Éoliennes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-6761-5
– 2 – IEC 61400-21-1:2019 © IEC 2019
CONTENTS
FOREWORD . 10
INTRODUCTION . 12
1 Scope . 13
2 Normative references . 13
3 Terms and definitions . 14
4 Symbols and units . 25
5 Abbreviated terms . 26
6 Wind turbine specification . 27
7 Test conditions and test systems . 27
7.1 General . 27
7.2 Overview of required test levels . 27
7.3 Test validity . 28
7.4 Test conditions . 29
7.5 Test equipment . 30
8 Measurement and test of electrical characteristics . 32
8.1 General . 32
8.2 Power quality aspects . 32
8.2.1 General . 32
8.2.2 Flicker during continuous operation . 32
8.2.3 Flicker and voltage change during switching operations . 35
8.2.4 Harmonics, interharmonics and higher frequency components . 38
8.3 Steady-state operation . 40
8.3.1 General . 40
8.3.2 Observation of active power against wind speed . 40
8.3.3 Maximum power . 42
8.3.4 Reactive power characteristic (Q = 0) . 44
8.3.5 Reactive power capability . 44
8.3.6 Voltage dependency of PQ diagram . 45
8.3.7 Unbalance factor . 46
8.4 Control performance . 47
8.4.1 General . 47
8.4.2 Active power control . 47
8.4.3 Active power ramp rate limitation . 50
8.4.4 Frequency control . 52
8.4.5 Synthetic inertia . 54
8.4.6 Reactive power control . 55
8.5 Dynamic performance . 58
8.5.1 General . 58
8.5.2 Fault ride-through capability . 58
8.6 Disconnection from grid . 66
8.6.1 General . 66
8.6.2 Grid protection . 66
8.6.3 Test of rate of change of frequency RoCoF (df/dt) protection device . 70
8.6.4 Reconnection test . 71
Annex A (informative) Reporting . 72
A.1 Overview. 72
IEC 61400-21-1:2019 © IEC 2019 – 3 –
A.2 General . 72
A.3 Power quality aspects . 74
A.4 Steady-state operation . 83
A.5 Dynamic performance (see 8.5) . 101
A.6 Disconnection from grid (see 8.6) . 106
Annex B (informative) Voltage fluctuations and flicker . 110
B.1 Continuous operation . 110
B.2 Switching operations . 110
B.3 Verification test of the measurement procedure for flicker . 111
B.3.1 General . 111
B.3.2 Fictitious grid performance testing . 112
B.3.3 Distorted u (t) voltage with multiple zero crossings . 113
m
B.3.4 Distorted u (t) voltage with inter-harmonic modulation . 113
m
B.3.5 Slow frequency changes . 114
B.4 Deduction of definitions. 114
B.4.1 Flicker coefficient . 114
B.4.2 Flicker step factor . 115
B.4.3 Voltage change factor . 116
Annex C (normative) Measurement of active power, reactive power and voltage . 117
C.1 General . 117
C.2 Generator convention of the signs . 117
C.3 Calculation of positive, negative and zero sequence quantities . 118
C.3.1 Phasor calculations . 118
C.3.2 Calculation of the positive sequence quantities using phasor
components . 121
C.3.3 Calculation of the negative sequence quantities using phasor
components . 122
C.3.4 Calculation of the zero sequence quantities using phasor components . 123
Annex D (informative) Harmonic evaluation . 125
D.1 General . 125
D.2 General analysis methods . 125
D.2.1 General . 125
D.2.2 Harmonic voltages . 125
D.2.3 Harmonic phase angles and magnitudes . 125
D.2.4 Statistical analysis . 129
D.2.5 Sample rate adjustment . 129
D.2.6 Determination of background harmonic voltage distortion . 129
D.2.7 Diurnal variations of the harmonic voltage and current . 129
D.2.8 Shutting down neighbouring WT or loads . 130
D.2.9 Harmonics of current and voltage over power . 130
D.2.10 Filters switching . 131
D.2.11 Measuring at a standard source . 132
D.2.12 Harmonics power flow + voltage measurement, phase angle . 132
D.2.13 Voltage harmonics with and without operation of the tested wind turbine . 133
D.2.14 Measurements at different sites . 134
D.2.15 Harmonic model. 134
D.3 Determination of harmonic amplitude affected by space harmonics at DFAG
systems . 134
– 4 – IEC 61400-21-1:2019 © IEC 2019
Annex E (informative) Assessment of power quality of wind turbines and wind power
plants. 136
E.1 General . 136
E.2 Voltage fluctuations . 136
E.2.1 General . 136
E.2.2 Continuous operation . 137
E.2.3 Switching operations . 137
E.3 Current harmonics, interharmonics and higher frequency components . 138
Annex F (informative) Guidelines for the transferability of test results to different
turbine variants in the same product platform . 140
Bibliography . 144
Figure 1 – Example of step response . 22
Figure 2 – Measurement system description including the most significant components . 31
Figure 3 – Fictitious grid for simulation of fictitious voltage . 33
Figure 4 – Active power as a function of the wind speed (example) . 41
Figure 5 – Number of measurements in power bins (example) . 42
Figure 6 – Number of measurements in wind speed bins (example) . 42
Figure 7 – Example of PQ capability diagram for a given voltage at WT level . 45
Figure 8 – Adjustment of active power reference value . 48
Figure 9 – Example of active power response step . 48
Figure 10 – Example of available active power and active power in ramp rate limitation
modefigue . 51
Figure 11 – Example of an active power control function P=f(f), with the different
measurement points and related steps of frequency . 52
Figure 12 – Synthetic inertia – definitions . 55
Figure 13 – Test for static error . 56
Figure 14 – Test of dynamic response (example) . 57
Figure 15 – Example UVRT test equipment . 59
Figure 16 – Tolerances of the positive sequence voltage for the undervoltage event
with disconnected WT under test . 60
Figure 17 – Tolerance of positive sequence overvoltage event. 61
Figure 18 – Example OVRT capacitor test unit . 62
Figure 19 – Example of an undervoltage test chart . 63
Figure 20 – Example of an overvoltage capability curve . 64
Figure 21 – Example of step ramp for overvoltage or frequency testing . 68
Figure 22 – Example of pulse ramp for over voltage or frequency testing . 69
Figure 23 – Example of the test levels to determine the release time . 69
Figure A.1 – Voltage flicker P vs. active power . 74
st
Figure A.2 – Flicker coefficient c(30°) vs. active power . 74
Figure A.3 – Flicker coefficient c(50°) vs. active power . 75
Figure A.4 – Flicker coefficient c(70°) vs. active power . 75
Figure A.5 – Flicker coefficient c(85°) vs. active power . 75
Figure A.6 – Time series of 3-phase voltages as RMS of start-up at the wind speed
of … m/s . 76
IEC 61400-21-1:2019 © IEC 2019 – 5 –
Figure A.7 – Time series of 3-phase currents as RMS of start-up at the wind speed
of … m/s . 76
Figure A.8 – Time series of active and reactive power of start-up at the wind speed
of … m/s . 76
Figure A.9 – Time series of 3-phase voltages as RMS of start-up at the wind speed
of … m/s . 77
Figure A.10 – Time series of 3-phase currents as RMS of start-up at the wind speed
of … m/s . 77
Figure A.11 – Time series of active and reactive power of start-up at the wind speed
of … m/s . 77
Figure A.12 – Time series of 3-phase voltages as RMS of change from generator stage
1 to stage 2. 78
Figure A.13 – Time series of 3-phase currents as RMS of change from generator stage
1 to stage 2. 78
Figure A.14 – Time series of active and reactive power of change from generator stage
1 to stage 2. 78
Figure A.15 – Time series of 3-phase voltages as RMS of change from generator stage
2 to stage 1. 78
Figure A.16 – Time series of 3-phase currents as RMS of change from generator stage
2 to stage 1. 78
Figure A.17 – Time series of active and reactive power of change from generator stage
2 to stage 1. 79
th
Figure A.18 – Max. of the 95 percentiles of integer harmonic currents vs. harmonic
order . 83
th
Figure A.19 – Max. of the 95 percentiles of interharmonic currents vs. frequency. 83
th
Figure A.20 – Max. of the 95 percentiles of higher frequency current components vs.
frequency . 83
Figure A.21 – Active power as a function of the wind speed . 84
Figure A.22 – Reactive power vs. active power . 85
Figure A.23 – PQ-Diagram . 86
Figure A.24 – PQ-Diagram . 87
Figure A.25 – PQ-Diagram . 88
Figure A.26 – Mean 1-min current unbalance factor over active power . 89
Figure A.27 – Time-series of active power reference values, available power and
measured active power output during active power control for the evaluation of the
static error . 89
Figure A.28 – Time-series of measured wind speed during active power control during
the test of the static error . 89
Figure A.29 – Time-series of active power reference values, available power and
measured active power output during active power control for the evaluation of the
settling time . 90
Figure A.30 – Time-series of available and measured active power output during ramp
rate limitation . 90
Figure A.31 – Time-series of measured wind speed during ramp rate limitation . 91
Figure A.32 – Time-series of available and measured active power output during ramp
rate limitation . 91
Figure A.33 – Time-series of measured wind speed during ramp rate limitation . 91
Figure A.34 – Time-series of available and measured active power output during ramp
rate limitation . 92
– 6 – IEC 61400-21-1:2019 © IEC 2019
Figure A.35 – Time-series of measured wind speed during ramp rate limitation . 92
Figure A.36 – Time-series of available and measured active power output during ramp
rate limitation . 93
Figure A.37 – Time-series of measured wind speed during ramp rate limitation . 93
Figure A.38 – Time-series of available power, measured active power and reference
value of the grid frequency change . 94
Figure A.39 – Time-series of measured wind speed . 94
Figure A.40 – Measured active power over frequency change . 94
Figure A.41 – Time-series of available power, measured active power and reference
value of the grid frequency change . 95
Figure A.42 – Time-series of measured wind speed . 95
Figure A.43 – Measured active power over frequency change . 95
Figure A.44 – Test 1, time-series of available power, measured active power and
reference value of the grid frequency for 0,25 × P < P < 0,5 × P . 96
n n
Figure A.45 – Test 1, time-series of wind speed for 0,25 × P < P < 0,5 × P . 96
n n
Figure A.46 – Test 2, time-series of available power, measured active power and
reference value of the grid frequency for 0,25 × P < P < 0,5 × P . 97
n n
Figure A.47 – Test 2, time-series of wind speed for 0,25 × P < P < 0,5 × P . 97
n n
Figure A.48 – Test 3, time-series of available power, measured active power and
reference values of the grid frequency for P > 0,8 × P . 97
n
Figure A.49 – Test 3, time-series of wind speed for P > 0,8 × P . 97
n
Figure A.50 – Test 4, time-series of available power, measured active power and
reference value of the grid frequency for P > 0,8 × P . 97
n
Figure A.51 – Test 4, time-series of wind speed for P > 0,8 × P . 98
n
Figure A.52 – Test 5, time-series of available power, measured active power and
reference value of the grid frequency for v > v . 98
n
Figure A.53 – Test 5, time-series of wind speed for v > v . 98
n
Figure A.54 – Test 6, time-series of available power, measured active power and
reference value of the grid frequency for v > v . 98
n
Figure A.55 – Test 6, time-series of wind speed for v > v . 98
n
Figure A.56 – Time-series of reactive power reference values and measured reactive
power during the test of reactive power control . 99
Figure A.57 – Time-series of active power during the test of reactive power control . 99
Figure A.58 – Time-series of reactive power reference values and measured reactive
power during the test of reactive power dynamic response. 100
Figure A.59 – Time-series of active power during the test of reactive power dynamic
response . 100
Figure A.60 – Wave shape of 3-phase voltages during entrance of voltage dip/swell
when the WT under test is not connected . 101
Figure A.61 – Wave shape of 3-phase voltages during clearance of voltage dip/swell
when the WT under test is not connected . 102
Figure A.62 – 3-phase voltages as RMS (1 line period) during the test when the WT
under test is not connected . 102
Figure A.63 – Positive sequence voltage during the test when the WT under test is not
connected . 102
Figure A.64 – Wave shape of 3-phase voltages during entrance of the voltage dip/swell
when the WT under test is connected . 104
Figure A.65 – Wave shape of 3-phase voltages during clearance of the voltage
dip/swell when the WT under test is connected . 104
IEC 61400-21-1:2019 © IEC 2019 – 7 –
Figure A.66 – 3-phase voltages as RMS (1 line period) during the test when the WT
under test is connected . 104
Figure A.67 – Positive and negative sequence fundamental voltage during the test
when the WT under test is connected . 104
Figure A.68 – 3-phase currents as RMS (1 line period) during the test when the WT
under test is connected . 104
Figure A.69 – Pos. and neg. sequence fundamental current during the test when the
WT under test is connected . 105
Figure A.70 – Pos. sequence fundamental active power during the test when the WT
under test is connected. . 105
Figure A.71 – Pos. sequence fundamental reactive power during the test when the WT
under test is connected . 105
Figure A.72 – Pos. sequence fundamental active current during the test when the WT
under test is connected . 105
Figure A.73 – Pos. sequence fundamental reactive current during the test when the
WT under test is connected . 105
Figure A.74 – Wind speed or available power during the test when the WT under test is
connected . 106
Figure A.75 – Voltage during the reconnection test of 10 s . 107
Figure A.76 – Active power during the reconnection test of 10 s, including the recovery . 107
Figure A.77 – Time-series of measured wind speed during the reconnection test of 10 s . 108
Figure A.78 – Voltage during the reconnection test of 60 s . 108
Figure A.79 – Active power during the reconnection test of 60 s, including the recovery . 108
Figure A.80 – Time-series of measured wind speed during the reconnection test of 60 s . 108
Figure A.81 – Voltage during the reconnection test of 600 s. 108
Figure A.82 – Active power during the reconnection test of 600 s including the recovery . 109
Figure A.83 – Time-series of measured wind speed during the reconnection test of
600 s . 109
Figure B.1 – Measurement procedure for flicker during continuous operation of the
wind turbine . 110
Figure B.2 – Measurement procedure for voltage changes and flicker during switching
operations of the wind turbine . 111
Figure C.1 – Positive directions of active power, reactive power, instantaneous phase
voltages and instantaneous phase currents with generator convention. 117
Figure C.2 – Examples of the power phasor diagrams of the generator convention in
each quadrant with respective instantaneous phase voltage and current . 118
Figure D.1 – Definition of the phase angles of the spectral line in generator convention
– (5th harmonic with αI5 = + 120° and αU5 = + 170°shown as an example, thus 5th
harmonic phase angle is φ5 = + 170° − 120° = + 50°) . 126
Figure D.2 – Comparison of harmonic amplitude aggregation (dotted) no aggregated
amplitude directly from DFT with 10-cycle window, (dashed) 10-second aggregation . 127
Figure D.3 – Comparison of the prevailing angle ratio (PAR) . 128
Figure F.1 – Block diagram for generic wind turbine (source IEC 61400-27-1) . 141
Table 1 – Overview of required test levels . 28
Table 2 – Specification of requirements for measurement equipment . 31
Table 3 – Number of 10-min time-series per wind speed bin . 41
Table 4 – Number of measurements per power bin (10 min average) . 41
– 8 – IEC 61400-21-1:2019 © IEC 2019
Table 5 – Measured maximum active power values . 43
Table 6 – Accuracy of the active power control values . 49
Table 7 – Results from the active power reference test . 49
Table 8 – Active power ramp rate calculation . 51
Table 9 – Example of Settings for the frequency dependent active power function . 53
Table 10 – Test for static error . 58
Table 11 – Test for dynamic response . 58
Table 12 – Example of undervoltage events . 63
Table 13 – Example of overvoltage tests . 65
Table 14 – Grid protection tests . 67
Table A.1 – General report information . 72
Table A.2 – General data . 73
Table A.3 – Nominal data . 73
Table A.4 – Test conditions. 73
th
Table A.5 – Flicker coefficient per power bin (95 percentile) . 74
Table A.6 – Start-up at cut in wind speed . 75
Table A.7 – Start-up at nominal active power . 76
Table A.8 – Worst-case switching between generators . 77
Table A.9 – General test information . 79
th
Table A.10 – 95 percentile of 10-min harmonic magnitudes per power bin . 79
th
Table A.11 – 95 percentile of 10-min harmonic magnitudes per power bin . 81
th
Table A.12 – 95 percentile of 10-min harmonic magnitudes per power bin . 82
Table A.13 – Active power against wind speed (see 8.3.2) . 83
Table A.14 – Measurement data set . 84
Table A.15 – Maximum active power . 84
Table A.16 – Reactive power characteristic. 85
Table A.17 – PQ-diagram. 86
Table A.18 – PQ-diagram at maximum voltage. 87
Table A.19 – PQ-diagram at minimum voltage . 88
Table A.20 – P-IUF diagram . 88
i
Table A.21 – General test information . 89
Table A.22 – Static error . 89
Table A.23 – Dynamic response . 90
Table A.24 – General test information . 90
Table A.25 – Active power ramp rate calculation at start-up .
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