IEC TR 62001-4:2021

High-voltage direct current (HVDC) systems - Guidance to the specification and design evaluation of AC filters - Part 4: Equipment

IEC TR 62001:2021, which is a Technical Report, provides guidance on the basic data of AC side filters for high-voltage direct current (HVDC) systems and their components such as ratings, power losses, design issues and special applications, protection, seismic requirements, equipment design and test parameters.
This document covers AC side filtering for the frequency range of interest in terms of harmonic distortion and audible frequency disturbances. It excludes filters designed to be effective in the power line carrier (PLC) and radio interference spectra. It concerns the conventional AC filter technology and LCC (line-commutated converter) HVDC but much of this applies to any filter equipment for VSC (voltage sourced converter) HVDC. This edition includes the following significant technical change with respect to the previous edition:
- general updating of the document to reflect changes in practice;
- Annex A deleted as its content is covered by IEC 61803.

General Information

• Status: Published
• Publication Date: 06-Sep-2021
• ICS: 29.200 - Rectifiers. Convertors. Stabilized power supply
• Technical Committee: SC 22F - Power electronics for electrical transmission and distribution systems
• Drafting Committee: MT 21 - TC 22/SC 22F/MT 21
• Current Stage: PPUB - Publication issued
• Start Date: 15-Sep-2021
• Completion Date: 07-Sep-2021

Relations

• Revises: IEC TR 62001-4:2016 - High-voltage direct current (HVDC) systems - Guidance to the specification and design evaluation of AC filters - Part 4: Equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TR 62001-4 ®
Edition 2.0 2021-09
TECHNICAL
REPORT
High-voltage direct current (HVDC) systems – Guidance to the specification and
design evaluation of AC filters –
Part 4: Equipment
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.: [phone]
3, rue de Varembé [e-mail]
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.

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IEC TR 62001-4 ®
Edition 2.0 2021-09
TECHNICAL
REPORT
High-voltage direct current (HVDC) systems – Guidance to the specification and

design evaluation of AC filters –

Part 4: Equipment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200 ISBN 978-2-8322-1013-0

– 2 – IEC TR 62001-4:2021 © IEC 2021
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references. 9
3 Terms and definitions . 9
4 Steady state rating . 9
4.1 General . 9
4.2 Calculation method . 9
4.2.1 General . 9
4.2.2 AC system pre-existing harmonics . 11
4.2.3 Combination of converter and pre-existing harmonics . 12
4.2.4 Equipment rating calculations . 12
4.2.5 Application of voltage ratings. 16
4.3 AC network conditions . 16
4.4 De-tuning effects . 16
4.5 Network impedance for rating calculations . 16
4.6 Outages . 17
5 Transient stresses and rating . 17
5.1 General . 17
5.2 Switching impulse studies . 18
5.2.1 Energization and switching . 18
5.2.2 Faults external to the filter . 20
5.2.3 Faults internal to the filter . 21
5.2.4 Transformer inrush currents . 22
5.3 Fast fronted waveform studies . 22
5.3.1 General . 22
5.3.2 Lightning strikes . 22
5.3.3 Busbar flashover studies . 22
5.4 Insulation co-ordination . 22
6 Losses . 24
6.1 Background . 24
6.2 AC filter component losses . 24
6.2.1 General . 24
6.2.2 Filter/shunt capacitor losses . 24
6.3 Reactor and resistor losses . 26
6.3.1 General . 26
6.3.2 Filter resistor losses . 27
6.3.3 Shunt reactor losses . 27
6.4 Criteria for loss evaluation . 27
6.4.1 General . 27
6.4.2 Fundamental frequency AC filter busbar voltage . 28
6.4.3 Fundamental frequency and ambient temperature . 28
6.4.4 AC system harmonic impedance . 28
6.4.5 Harmonic currents generated by the converter . 29
6.4.6 Pre-existing harmonic distortion . 29
6.4.7 Anticipated load profile of the converter station . 29

7 Design issues and special applications . 30
7.1 General . 30
7.2 Performance aspects . 30
7.2.1 Low order harmonic filtering and resonance conditions with AC system . 30
7.2.2 Definition of interference factors to include harmonics up to 5 kHz . 31
7.2.3 Triple-tuned filter circuits . 32
7.2.4 Harmonic AC filters on tertiary winding of converter transformers . 33
7.3 Rating aspects . 34
7.3.1 Limiting high harmonic currents in parallel-resonant filter circuits . 34
7.3.2 Transient ratings of parallel circuits in multiple tuned filters . 34
7.3.3 Overload protection of high-pass harmonic filter resistors . 34
7.3.4 Back-to-back switching of filters or shunt capacitors . 35
7.3.5 Short time overload – reasonable specification of requirements . 35
7.3.6 Low voltage filter capacitors without fuses . 36
7.4 Filters for special purposes . 36
7.4.1 Harmonic filters for damping transient overvoltages . 36
7.4.2 Non-linear filters for low order harmonics/transient overvoltages . 37
7.4.3 Series filters for HVDC converter stations . 38
7.4.4 Re-tunable AC filters . 41
7.5 Impact of new HVDC station in vicinity of an existing station . 42
7.6 Redundancy issues and spares . 43
7.6.1 Redundancy of filters – Savings in ratings and losses . 43
7.6.2 Internal filter redundancy . 44
7.6.3 Spare parts . 44
8 Protection . 45
8.1 Overview. 45
8.2 General . 45
8.3 Bank and sub-bank overall protection . 47
8.3.1 General . 47
8.3.2 Short-circuit protection . 47
8.3.3 Overcurrent protection . 47
8.3.4 Thermal overload protection . 47
8.3.5 Differential protection . 48
8.3.6 Earth fault protection . 48
8.3.7 Overvoltage and undervoltage protection . 48
8.3.8 Special protection functions and harmonic measurements . 49
8.3.9 Busbar and breaker failure protection . 49
8.4 Protection of individual filter components . 49
8.4.1 Unbalance protection for filter and shunt capacitors . 49
8.4.2 Protection of low voltage tuning capacitors . 51
8.4.3 Overload protection and detection of filter detuning . 51
8.4.4 Temperature measurement for protection . 51
8.4.5 Measurement of fundamental frequency components . 51
8.4.6 Capacitor fuses . 51
8.4.7 Protection and rating of instrument transformers . 52
8.4.8 Examples of protection arrangements . 53
8.5 Personnel protection . 53
9 Audible noise . 56
9.1 General . 56

– 4 – IEC TR 62001-4:2021 © IEC 2021
9.2 Sound active components of AC filters . 56
9.3 Sound requirements . 58
9.4 Noise reduction . 58
10 Seismic requirements . 59
10.1 General .
...

IEC TR 62001-4 ®
Edition 2.0 2021-09
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) systems – Guidance to the specification and
design evaluation of AC filters –
Part 4: Equipment
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.: [phone]
3, rue de Varembé [e-mail]
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: [e-mail].
IEC TR 62001-4 ®
Edition 2.0 2021-09
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) systems – Guidance to the specification and
design evaluation of AC filters –
Part 4: Equipment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200 ISBN 978-2-8322-4531-6

– 2 – IEC TR 62001-4:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references. 9
3 Terms and definitions . 9
4 Steady state rating . 9
4.1 General . 9
4.2 Calculation method . 10
4.2.1 General . 10
4.2.2 AC system pre-existing harmonics . 11
4.2.3 Combination of converter and pre-existing harmonics . 12
4.2.4 Equipment rating calculations . 12
4.2.5 Application of voltage ratings. 16
4.3 AC network conditions . 17
4.4 De-tuning effects . 17
4.5 Network impedance for rating calculations . 17
4.6 Outages . 18
5 Transient stresses and rating . 18
5.1 General . 18
5.2 Switching impulse studies . 19
5.2.1 Energization and switching . 19
5.2.2 Faults external to the filter . 21
5.2.3 Faults internal to the filter . 22
5.2.4 Transformer inrush currents . 23
5.3 Fast fronted waveform studies . 23
5.3.1 General . 23
5.3.2 Lightning strikes . 23
5.3.3 Busbar flashover studies . 23
5.4 Insulation co-ordination . 23
6 Losses . 25
6.1 Background . 25
6.2 AC filter component losses . 25
6.2.1 General . 25
6.2.2 Filter/shunt capacitor losses . 26
6.3 Reactor and resistor losses . 27
6.3.1 General . 27
6.3.2 Filter resistor losses . 28
6.3.3 Shunt reactor losses . 28
6.4 Criteria for loss evaluation . 28
6.4.1 General . 28
6.4.2 Fundamental frequency AC filter busbar voltage . 29
6.4.3 Fundamental frequency and ambient temperature . 29
6.4.4 AC system harmonic impedance . 29
6.4.5 Harmonic currents generated by the converter . 30
6.4.6 Pre-existing harmonic distortion . 30
6.4.7 Anticipated load profile of the converter station . 31

7 Design issues and special applications . 31
7.1 General . 31
7.2 Performance aspects . 31
7.2.1 Low order harmonic filtering and resonance conditions with AC system . 31
7.2.2 Definition of interference factors to include harmonics up to 5 kHz . 32
7.2.3 Triple-tuned filter circuits . 33
7.2.4 Harmonic AC filters on tertiary winding of converter transformers . 34
7.3 Rating aspects . 35
7.3.1 Limiting high harmonic currents in parallel-resonant filter circuits . 35
7.3.2 Transient ratings of parallel circuits in multiple tuned filters . 35
7.3.3 Overload protection of high-pass harmonic filter resistors . 36
7.3.4 Back-to-back switching of filters or shunt capacitors . 36
7.3.5 Short time overload – reasonable specification of requirements . 36
7.3.6 Low voltage filter capacitors without fuses . 37
7.4 Filters for special purposes . 38
7.4.1 Harmonic filters for damping transient overvoltages . 38
7.4.2 Non-linear filters for low order harmonics/transient overvoltages . 38
7.4.3 Series filters for HVDC converter stations . 39
7.4.4 Re-tunable AC filters . 42
7.5 Impact of new HVDC station in vicinity of an existing station . 43
7.6 Redundancy issues and spares . 44
7.6.1 Redundancy of filters – Savings in ratings and losses . 44
7.6.2 Internal filter redundancy . 45
7.6.3 Spare parts . 45
8 Protection . 46
8.1 Overview. 46
8.2 General . 46
8.3 Bank and sub-bank overall protection . 48
8.3.1 General . 48
8.3.2 Short-circuit protection . 48
8.3.3 Overcurrent protection . 48
8.3.4 Thermal overload protection . 48
8.3.5 Differential protection . 49
8.3.6 Earth fault protection . 49
8.3.7 Overvoltage and undervoltage protection . 49
8.3.8 Special protection functions and harmonic measurements . 50
8.3.9 Busbar and breaker failure protection . 50
8.4 Protection of individual filter components . 50
8.4.1 Unbalance protection for filter and shunt capacitors . 50
8.4.2 Protection of low voltage tuning capacitors . 52
8.4.3 Overload protection and detection of filter detuning . 52
8.4.4 Temperature measurement for protection . 52
8.4.5 Measurement of fundamental frequency components . 52
8.4.6 Capacitor fuses . 53
8.4.7 Protection and rating of instrument transformers . 53
8.4.8 Examples of protection arrangements . 54
8.5 Personnel protection . 54
9 Audible noise . 57
9.1 General . 57

– 4 – IEC TR 62001-4:2021 RLV © IEC 2021
9.2 Sound active components of AC filters . 57
9.3 Sound requirements . 59
9.4 Noise reduction . 59
10 Seismic requirements . 60
10.1 General .
...