IEC TR 61400-21-3:2019

Wind energy generation systems - Part 21-3: Measurement and assessment of electrical characteristics - Wind turbine harmonic model and its application

IEC TR 61400-21-3:2019 provides guidance on principles which can be used as the basis for determining the application, structure and recommendations for the WT harmonic model. For the purpose of this Technical Report, a harmonic model means a model that represents harmonic emissions of different WT types interacting with the connected network.
This document is focused on providing technical guidance concerning the WT harmonic model. It describes the harmonic model in detail, covering such aspects as application, structure, as well as validation. By introducing a common understanding of the WT representation from a harmonic performance perspective, this document aims to bring the overall concept of the harmonic model closer to the industry (e.g. suppliers, developers, system operators, academia, etc.).
A standardized approach of WT harmonic model representation is presented in this document. The harmonic model will find a broad application in many areas of electrical engineering related to design, analysis, and optimisation of electrical infrastructure of onshore as well as offshore WPPs.

General Information

• Status: Published
• Publication Date: 12-Sep-2019
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Current Stage: PPUB - Publication issued
• Start Date: 10-Sep-2019
• Completion Date: 13-Sep-2019

Standards Content (Sample)

IEC TR 61400-21-3 ®
Edition 1.0 2019-09
TECHNICAL
REPORT
colour
inside
Wind energy generation systems –
Part 21-3: Measurement and assessment of electrical characteristics – Wind
turbine harmonic model and its application
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IEC TR 61400-21-3 ®
Edition 1.0 2019-09
TECHNICAL
REPORT
colour
inside
Wind energy generation systems –

Part 21-3: Measurement and assessment of electrical characteristics – Wind

turbine harmonic model and its application

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-7288-6

– 2 – IEC TR 61400-21-3:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms, definitions and abbreviations . 8
3.1 Terms and definitions . 8
3.2 Abbreviations . 12
4 General description . 13
4.1 Overview. 13
4.2 Background. 14
5 Recommendations of minimal requirements . 17
5.1 General . 17
5.2 Application . 18
5.3 Input parameters . 18
5.4 Harmonic model terminal . 18
5.5 Output variables. 19
5.6 Structure . 19
6 Interfaces to other IEC documents . 20
6.1 IEC 61400-21-1:2019, Annex D – Harmonic evaluation . 20
6.2 IEC 61400-21-1:2019, Annex E – Assessment of power quality of wind
turbines and wind power plants . 21
7 Harmonic model . 21
7.1 General . 21
7.2 Thévenin/Norton equivalent circuit . 22
7.3 Equivalent harmonic voltage/current sources . 22
7.3.1 General . 22
7.3.2 Harmonic equivalent impedance . 23
7.4 Wind turbine types . 24
7.4.1 General . 24
7.4.2 Type 1 and Type 2 . 24
7.4.3 Type 3 . 25
7.4.4 Type 4 . 26
8 Validation . 28
8.1 General . 28
8.2 Overview. 28
8.3 Model validation . 29
8.4 Fictitious grid . 30
9 Limitations . 30
Bibliography . 32

Figure 1 – Example of a phase angle between the harmonic current and the harmonic
voltage component as well as the fundamental voltage . 9
Figure 2 – Example of wind power plant typical components relevant for the harmonic
studies and potential challenges in harmonic performance . 14
Figure 3 – Example of a WPP complex structure . 15
Figure 4 – Example of a WPP complex electrical infrastructure with many WTs . 16

Figure 5 – Harmonic impedance estimated at the point of connection specified in
Figure 4 . 17
Figure 6 – Generic harmonic model structure represented as Norton/Thévenin

equivalent circuit . 20
Figure 7 – Main electrical and mechanical components of Type 3 WTs [6] . 25
Figure 8 – Example of a structure of a DFAG harmonic model (from [13]) . 26
Figure 9 – Main electrical and mechanical components of Type 4 WTs [6] . 26
Figure 10 – Example of a converter harmonic model as Thévenin equivalent circuit
together with an example of a WT power circuit (from [9]) . 27
Figure 11 – Harmonic voltage comparison for respective power bins . 28

Table 1 – Example of a representation/template of the harmonic voltage source . 23
Table 2 – Example of a representation/template of the harmonic current source . 23
Table 3 – Example of a representation/template of the harmonic equivalent impedance . 24

– 4 – IEC TR 61400-21-3:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS –

Part 21-3: Measurement and assessment of electrical characteristics –
Wind turbine harmonic model and its application

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61400-21-3, which is a Technical Report, has been prepared by IEC Technical
Committee 88: Wind energy generation systems.
The text of this Technical Report is based on the following documents:
DTR Report on voting
88/698/DTR 88/717/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61400 series, published under the general title Wind energy
generation systems, can be found on t
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