SIST EN IEC 60071-12:2023

SLOVENSKI STANDARD
SIST EN IEC 60071-12:2023
01-januar-2023
Nadomešča:
SIST EN 60071-5:2015
Koordinacija izolacije - 12. del: Smernice za uporabo LCC HVDC
(visokonapetostnih enosmernih) pretvorniških postaj
Insulation co-ordination - Part 12: Application guidelines for LCC HVDC converter
stations
Ta slovenski standard je istoveten z: EN IEC 60071-12:2022
ICS:
29.080.30 Izolacijski sistemi Insulation systems
SIST EN IEC 60071-12:2023 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60071-12:2023

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SIST EN IEC 60071-12:2023


EUROPEAN STANDARD EN IEC 60071-12

NORME EUROPÉENNE

EUROPÄISCHE NORM November 2022
ICS 29.080.30
Supersedes EN 60071-5:2015 (partially)
English Version
Insulation co-ordination - Part 12: Application guidelines for LCC
HVDC converter stations
(IEC 60071-12:2022)
Coordination de l'isolement - Partie 12: Lignes directrices Isolationskoordination für HVDC Systeme - Teil 12:
en matière d'application pour stations de conversion à Anwendungsrichtlinien für Stromrichterstationen mit
courant continu haute tension (CCHT) équipées de Stromzwischenkreis-Konverter (LCC)
convertisseurs commutés par le réseau (LCC) (IEC 60071-12:2022)
(IEC 60071-12:2022)
This European Standard was approved by CENELEC on 2022-11-18. 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,
Türkiye 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
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60071-12:2022 E

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SIST EN IEC 60071-12:2023
EN IEC 60071-12:2022 (E)
European foreword
The text of document 99/368/FDIS, future edition 1 of IEC 60071-12, prepared by IEC/TC 99
"Insulation co-ordination and system engineering of high voltage electrical power installations above
1,0 kV AC and 1,5 kV DC" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 60071-12:2022.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-08-18
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2025-11-18
document have to be withdrawn
This document partially supersedes EN 60071-5:2015 and all of its amendments and corrigenda (if
any).
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.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60071-12:2022 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60060-1 NOTE Harmonized as EN 60060-1
IEC 60071-1:2019 NOTE Harmonized as EN IEC 60071-1:2019 (not modified)
IEC 60071-2:2018 NOTE Harmonized as EN IEC 60071-2:2018 (not modified)
IEC 60071-5:2014 NOTE Harmonized as EN 60071-5:2015 (not modified)
IEC 60099-5:2018 NOTE Harmonized as EN IEC 60099-5:2018 (not modified)
IEC 60099-9:2014 NOTE Harmonized as EN 60099-9:2014 (not modified)
IEC 60505:2011 NOTE Harmonized as EN 60505:2011 (not modified)
IEC 60700-1:2015/AMD1:2021 NOTE Harmonized as EN 60700-1:2015/A1:2021 (not modified)
IEC 60721-3-0:2020 NOTE Harmonized as EN IEC 60721-3-0:2020 (not modified)
2

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SIST EN IEC 60071-12:2023
EN IEC 60071-12:2022 (E)
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
1 2
IEC 60071-11 - Insulation co-ordination - Part 11 - EN IEC 60071-11 -
Definitions, principles and rules for HVDC
system
IEC 60099-4 - Surge arresters - Part 4: Metal-oxide EN 60099-4 -
surge arresters without gaps for a.c.
systems
IEC 60633 - High-voltage direct current (HVDC) EN IEC 60633 -
transmission - Vocabulary


1
Under preparation. Stage at the time of publication: IEC/CFDIS 60071-11:2022.
2
Under preparation. Stage at the time of publication: FprEN IEC 60071-11:2022.
3

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SIST EN IEC 60071-12:2023

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SIST EN IEC 60071-12:2023



IEC 60071-12

®


Edition 1.0 2022-10




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Insulation co-ordination –

Part 12: Application guidelines for LCC HVDC converter stations



Coordination de l’isolement –

Partie 12: Lignes directrices en matière d’application pour stations de

conversion à courant continu haute tension (CCHT) équipées de convertisseurs


commutés par le réseau (LCC)













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.080.30 ISBN 978-2-8322-5845-3




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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

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

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SIST EN IEC 60071-12:2023
– 2 – IEC 60071-12:2022 © IEC 2022
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviated terms . 7
3.1 Terms and definition . 7
3.2 Symbols and abbreviated terms . 8
3.2.1 General . 8
3.2.2 Subscripts . 8
3.2.3 Letter symbols . 8
3.2.4 Abbreviated terms . 9
4 Typical LCC HVDC converter station schemes . 9
5 Voltages and overvoltages in service . 12
5.1 Continuous operating voltages at various locations in the converter station . 12
5.2 Peak continuous operating voltage (PCOV) and crest continuous operating
voltage (CCOV) . 16
5.3 Sources and types of overvoItages . 18
5.4 Temporary overvoltage . 18
5.4.1 General . 18
5.4.2 Temporary overvoltage on the AC side . 18
5.4.3 Temporary overvoltages on the DC side . 19
5.5 Slow-front overvoltages . 19
5.5.1 General . 19
5.5.2 Slow-front overvoltages on the AC side . 19
5.5.3 Slow-front overvoltages on the DC side . 20
5.6 Fast-front, very-fast-front and steep-front overvoltages . 20
6 Arrester characteristics and stresses . 21
6.1 Arrester characteristics . 21
6.2 Arrester specification . 22
6.3 Arrester stresses. 23
6.3.1 General . 23
6.3.2 AC bus arrester (A) . 24
6.3.3 AC filter arrester (FA) . 24
6.3.4 Transformer valve winding arresters (T). 25
6.3.5 Valve arrester (V) . 25
6.3.6 Bridge arrester (B) . 28
6.3.7 Converter unit arrester (C) . 28
6.3.8 Mid-point DC bus arrester (M) . 29
6.3.9 Converter unit DC bus arrester (CB) . 29
6.3.10 DC bus and DC line/cable arrester (DB and DL/DC) . 30
6.3.11 Neutral bus arrester (E, EL, EM in Figure 3, EB, E1, EL, EM in Figure 1) . 30
6.3.12 DC reactor arrester (DR) . 31
6.3.13 DC filter arrester (FD) . 32
6.3.14 Earth electrode station arrester. 32
6.4 Protection strategy . 32
6.4.1 General . 32
6.4.2 Insulation directly protected by a single arrester . 32
6.4.3 Insulation protected by more than one arrester in series . 32

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SIST EN IEC 60071-12:2023
IEC 60071-12:2022 © IEC 2022 – 3 –
6.4.4 Valve side neutral point of transformers . 33
6.4.5 Insulation between phase conductors of the converter transformer . 33
6.4.6 Summary of protection strategy . 33
6.5 Summary of events and stresses . 36
7 Design procedure of insulation co-ordination . 37
7.1 General . 37
7.2 Arrester requirements . 38
7.3 Representative overvoltages (U ) . 38
rp
7.4 Determination of the co-ordination withstand voltages (U ) . 40
cw
7.5 Determination of the required withstand voltages (U ) . 40
rw
7.6 Determination of the specified withstand voltage (U ) . 40
w
8 Study tools and system modelling . 40
8.1 General . 40
8.2 Study approach and tooIs . 40
8.3 System details . 41
8.3.1 Modelling and system representation . 41
8.3.2 AC network and AC side of the LCC HVDC converter station . 43
8.3.3 DC overhead line/cable and earth electrode line details . 44
8.3.4 DC side of an LCC HVDC converter station details . 44
Annex A (informative) Example of insulation co-ordination for LCC HVDC converter
stations . 45
A.1 General . 45
A.2 Example for LCC HVDC converter station in a pole with one 12-pulse

converter . 45
A.2.1 Arrester protective scheme . 45
A.2.2 Arrester stresses, protection and insulation levels . 45
A.2.3 Transformer valve side withstand voltages. 50
A.2.4 Air-insulated smoothing reactors withstand voltages . 50
A.2.5 Results . 52
A.3 Example for LCC HVDC converter station in a pole with two 12-pulse
converters in series . 54
A.3.1 Arrester protective scheme . 54
A.3.2 Arrester stresses, protection and insulation levels . 55
A.3.3 Transformer valve side withstand voltages. 59
A.3.4 Smoothing reactor withstand voltages . 61
A.3.5 Results . 62
Bibliography . 64

Figure 1 – Possible arrester locations in a pole with two 12-pulse converters in series . 11
Figure 2 – Possible arrester locations for a back-to-back converter station . 12
Figure 3 – LCC HVDC converter station in a pole with one 12-pulse converter . 13
Figure 4 – Continuous operating voltages at various locations (location identification
according to Figure 3) . 15
Figure 5 – Operating voltage of a valve arrester (V), rectifier operation and definition of
PCOV and CCOV . 17
Figure 6 – Operating voltage of a mid-point arrester (M), rectifier operation . 17
Figure 7 – Operating voltage of a converter bus arrester (CB), rectifier operation . 17
Figure 8 – One pole of an LCC HVDC converter station . 43

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Figure A.1 – AC and DC arresters (LCC HVDC converter station in a pole with one 12-
pulse converter) . 52
Figure A.2 – Valve arrester stresses for slow-front overvoltages from AC side . 53
Figure A.3 – Arrester V2 stress for slow-front overvoltage from AC side . 53
Figure A.4 – Valve arrester stresses for earth fault between valve and upper bridge

transformer bushing . 54
Figure A.5 – Arrester V1 stress for earth fault between valve and upper bridge
transformer bushing . 54
Figure A.6 – AC and DC arresters (LCC HVDC converter station in a pole with two 12-
pulse converters in series) . 63

Table 1 – Symbol description . 12
Table 2 – Arrester protection on the DC side: one 12-pulse converter (Figure 3) . 34
Table 3 – Arrester protection on the DC side: two 12-pulse converters in series
(Figure 1) . 35
Table 4 – Events stressing arresters: one 12-pulse converter (Figure 3) . 36
Table 5 – Types of arrester stresses for different events: one 12-pulse converter
(Figure 3) . 37
Table 6 – Arrester requirements . 38
Table 7 – Representative overvoltages and required withstand voltages . 39
Table 8 – Origin of overvoltages and associated frequency ranges . 42

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SIST EN IEC 60071-12:2023
IEC 60071-12:2022 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

INSULATION CO-ORDINATION –

Part 12: Application guidelines for LCC HVDC converter stations

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60071-12 has been prepared by IEC technical committee 99: Insulation co-ordination and
system engineering of high voltage electrical power installations above 1,0 kV AC and 1,5 kV
DC. It is an International Standard.
On the basis of technical experience gained and the development of HVDC, sufficient
consensus has emerged to establish a series insulation co-ordination standard for HVDC
system. The standard series for HVDC system belongs to IEC 60071 standard series, and a list
of all parts in the IEC 60071 series, published under the general title Insulation co-ordination,
can be found on the IEC website.

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– 6 – IEC 60071-12:2022 © IEC 2022
1
This International Standard replaces, in conjunction with IEC 60071-11 , IEC 60071-5
published in 2014. IEC 60071-5 provides basic principles and guidance for insulation
coordination of high-voltage direct current (HVDC) converter stations. IEC 60071-11 specifies
the principles on the procedures for the determination of the specified withstand voltages,
creepage distance and air clearances for the equipment and the installations of these systems.
IEC 60071-12 provides guidelines on the procedures for insulation co-ordination of line
commutated converter (LCC) stations for high-voltage direct current (HVDC) project, whose aim
is to give guidance for the determination of the specified withstand voltages for equipment.
IEC 60071-12 retains the technical content of IEC 60071-5 of the guidelines on the procedures
for insulation coordination of LCC converter stations, and there are no essentially technical
amendments. An example for LCC HVDC converter station in a pole with two 12-pulse
converters in series is provided in annex. Examples of insulation co-ordination for controlled
series capacitor converter (CSCC) and capacitor commutated converters (CCC) in IEC 60071-
5 are no longer dealt with in this document.
The text of this International Standard is based on the following documents:
Draft Report on voting
99/368/FDIS 99/379/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.
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.


___________
1
 Under preparation. Stage at the time of publication: IEC/CFDIS 60071-11:2022.

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SIST EN IEC 60071-12:2023
IEC 60071-12:2022 © IEC 2022 – 7 –
INSULATION CO-ORDINATION –

Part 12: Application guidelines for LCC HVDC converter stations



1 Scope
This part of IEC 60071 applies guidelines on the procedures for insulation co-ordination of line
commutated converter (LCC) stations for high-voltage direct current (HVDC) project, whose aim
is evaluating the overvoltage stresses on the converter station equipment subjected to
combined DC, AC power frequency, harmonic and impulse voltages, and determining the
specified withstand voltages for equipment.
This document deals only with metal-oxide surge arresters, without gaps, which are used in
modern HVDC converter stations. The criteria for determining the protective levels of series
and/or parallel combinations of surge arresters used to ensure optimal protection are also
presented. Typical arrester protection schemes and stresses of arresters are presented.
Annex A contains examples of insulation co-ordination for LCC HVDC converters which support
the concepts described in the main text, and the basic analytical techniques used.
2 Normative references
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.
2
IEC 60071-11 , Insulation co-ordination – Part 11：Definitions, principles and rules for HVDC
system
IEC 60099-4, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.
systems
IEC 60633, High-voltage direct current (HVDC) transmission – Vocabulary
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definition
For the purposes of this document, the terms and definitions given in IEC 60071-11 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
___________
2
 Under preparation. Stage at the time of publication: IEC/CFDIS 60071-11:2022.

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3.1.1
crest value of continuous operating voltage
CCOV
highest continuously occurring crest value
...