IEC TR 62001-5:2021

IEC TR 62001-5 ®
Edition 1.0 2021-08
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) systems – Guidance to the specification and
design evaluation of AC filters –
Part 5: AC side harmonics and appropriate harmonic limits for HVDC systems
with voltage sourced converters (VSC)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TR 62001-5 ®
Edition 1.0 2021-08
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) systems – Guidance to the specification and

design evaluation of AC filters –

Part 5: AC side harmonics and appropriate harmonic limits for HVDC systems

with voltage sourced converters (VSC)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200 ISBN 978-2-8322-1008-2

– 2 – IEC TR 62001-5:2021 © IEC 2021
CONTENTS
FOREWORD . 8
INTRODUCTION . 10
1 Scope . 12
2 Normative references . 12
3 Terms, definitions and abbreviated terms . 12
3.1 Terms and definitions. 12
3.2 Abbreviated terms . 13
4 Basic aspects of VSC HVDC harmonics . 14
4.1 General . 14
4.2 Differences between VSC and LCC harmonic behaviour . 15
4.3 Issues relating to VSC harmonics . 16
4.4 Range of frequencies considered . 17
4.5 Equivalent circuit of the converter for harmonic analysis . 18
4.6 Dual impact of a VSC converter on harmonic distortion at PCC . 19
4.6.1 General . 19
4.6.2 Converter generated harmonics . 19
4.6.3 Pre-existing harmonics . 20
4.6.4 Combining the effects of converter-generated and pre-existing
harmonics . 21
5 Harmonic generation . 22
5.1 General . 22
5.2 Factors influencing harmonic generation . 23
5.2.1 General . 23
5.2.2 Converter topology . 23
5.2.3 Control . 25
5.2.4 Power electronics hardware . 27
5.3 Harmonic generation . 29
5.3.1 General . 29
5.3.2 Harmonic generation from VSC using switch type valves . 29
5.3.3 Harmonic generation from VSC using controllable voltage source type
valves . 38
5.4 Interharmonics . 44
5.5 Impact of non-ideal conditions on harmonic generation . 47
6 VSC HVDC as a harmonic impedance . 48
6.1 General . 48
6.2 Passive impedance . 49
6.3 Active impedance. 49
6.3.1 General . 49
6.3.2 Ideal VSC behaviour . 49
6.3.3 Impact of practical control system features . 50
6.3.4 Example of impact of control . 51
6.4 Impact on amplification of pre-existing harmonics . 52
7 Adverse effects of VSC HVDC harmonics . 53
7.1 General . 53
7.2 Telephone interference . 54
7.2.1 General . 54
7.2.2 Extended higher frequency range of VSC harmonics . 54

7.2.3 Interharmonics . 54
7.2.4 AC cable connecting HVDC station to the PCC . 55
7.3 PLC, metering and ripple control . 55
7.3.1 General . 55
7.3.2 Extended higher frequency range of VSC harmonics . 56
7.3.3 Interharmonics . 56
7.4 Railway signal interference . 57
7.5 Digital telecommunications systems . 57
8 Harmonic limits . 58
8.1 General . 58
8.2 Deleterious effects of excessively low limits . 58
8.3 Standards and practice . 59
8.4 Perception of VSC in setting limits . 60
8.5 Emission and amplification limits . 60
8.6 Relevance of standards for VSC . 61
8.7 Existing standards . 61
8.8 Higher frequency harmonics . 62
8.8.1 General . 62
8.8.2 IEEE Std 519-2014 [7] . 63
8.8.3 Shortcomings in the context of VSC . 64
8.9 Even order harmonic limits . 64
8.10 Interharmonics . 64
8.10.1 General . 64
8.10.2 Treatment of interharmonics in existing standards . 65
8.10.3 Discussion and recommendations . 66
8.11 Interharmonics discretization and grouping methodologies. 67
8.11.1 Suggested method . 67
8.11.2 Power quality indices for interharmonic grouping . 70
8.11.3 Network impedance loci for interharmonic grouping . 71
8.12 Assessment as a harmonic voltage or current source . 72
8.13 Assessment of THD, TIF, THFF, IT . 73
8.14 Measurement and verification of harmonic compliance . 74
8.15 Recommendations . 75
9 Harmonic mitigation techniques . 76
9.1 General . 76
9.2 Passive filtering . 76
9.3 Active damping and active filtering by converter control . 78
9.4 Optimization between passive and active mitigation . 79
9.5 Specific mitigation issues and techniques . 79
9.5.1 Unbalanced phase reactances or voltages . 79
9.5.2 Power oscillations due to AC supply voltage unbalance . 83
9.5.3 Harmonic cross-modulation between AC and DC sides . 85
9.5.4 Cross-modulation of DC side fundamental frequency current . 87
10 Modelling . 88
10.1 Provision of models . 88
10.2 Time and frequency domain . 88
10.3 Modelling of the converter control for harmonic and resonance studies . 89
10.4 Converter linearization by analytical approach . 90
10.4.1 General . 90

– 4 – IEC TR 62001-5:2021 © IEC 2021
10.4.2 VSC-MMC linearized model .
...