SIST EN IEC 60700-3:2023
(Main)Thyristor valves for high voltage direct current (HVDC) power transmission - Part 3: Essential ratings (limiting values) and characteristics
Thyristor valves for high voltage direct current (HVDC) power transmission - Part 3: Essential ratings (limiting values) and characteristics
This part of IEC 60700 specifies the service conditions, the definitions of essential ratings and characteristics of thyristor valves utilized in line commutated converters with three-phase bridge connections to realize the conversion from AC to DC and vice versa for high voltage direct current (HVDC) power transmission applications. It is applicable for air insulated, liquid cooled and indoor thyristor valves.
Thyristorventile für Hochspannungsgleichstrom - Energieübertragung (HGÜ) – Teil 3: Wesentliche Nenngrößen (begrenzende Werte) und Eigenschaften
Valves à thyristors pour le transport d’énergie en courant continu à haute tension (CCHT) - Partie 3: Valeurs assignées (valeurs limites) et caractéristiques essentielles
L’IEC 60700-3:2022 spécifie les conditions d’emploi, les définitions des valeurs assignées et des caractéristiques essentielles des valves à thyristors utilisées dans les convertisseurs commutés par le réseau avec des montages en pont triphasés pour réaliser la conversion du courant alternatif en courant continu et inversement pour des applications de transport d’énergie en courant continu à haute tension (CCHT). Elle s’applique aux valves à thyristors isolées par air, refroidies par un liquide et en intérieur.
Tiristorski ventili za visokonapetostni enosmerni prenos (HVDC) električne energije - 3. del: Bistvene lastnosti (mejne vrednosti) in karakteristike
Ta del standarda IEC 60700 določa delovne pogoje, bistvene vrednosti in lastnosti tiristorskih ventilov, ki se uporabljajo v vodovno komutiranimi pretvornikih s povezavami trifaznega mostu za pretvorbo izmeničnega toka v enosmerni tok in obratno za prenos električne energije z visokonapetostnim enosmernim tokom (HVDC). Uporablja se za zračno izolirane, tekočinsko hlajene in notranje tiristorske ventile.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-april-2023
Tiristorski ventili za visokonapetostni enosmerni prenos (HVDC) električne
energije - 3. del: Bistvene lastnosti (mejne vrednosti) in karakteristike
Thyristor valves for high voltage direct current (HVDC) power transmission - Part 3:
Essential ratings (limiting values) and characteristics
Thyristorventile für Hochspannungsgleichstrom - Energieübertragung (HGÜ) – Teil 3:
Wesentliche Nenngrößen (begrenzende Werte) und Eigenschaften
Valves à thyristors pour le transport d’énergie en courant continu à haute tension
(CCHT) - Partie 3: Valeurs assignées (valeurs limites) et caractéristiques essentielles
Ta slovenski standard je istoveten z: EN IEC 60700-3:2023
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
31.080.20 Tiristorji Thyristors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 60700-3
NORME EUROPÉENNE
EUROPÄISCHE NORM January 2023
ICS 29.200
English Version
Thyristor valves for high voltage direct current (HVDC) power
transmission - Part 3: Essential ratings (limiting values) and
characteristics
(IEC 60700-3:2022)
Valves à thyristors pour le transport d'énergie en courant Thyristorventile für Hochspannungsgleichstrom -
continu à haute tension (CCHT) - Partie 3: Valeurs Energieübertragung (HGÜ) - Teil 3: Wesentliche
assignées (valeurs limites) et caractéristiques essentielles Nenngrößen (begrenzende Werte) und Eigenschaften
(IEC 60700-3:2022) (IEC 60700-3:2022)
This European Standard was approved by CENELEC on 2023-01-03. 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
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60700-3:2023 E
European foreword
The text of document 22F/667/CDV, future edition 1 of IEC 60700-3, prepared by SC 22F "Power
electronics for electrical transmission and distribution systems" of IEC/TC 22 "Power electronic
systems and equipment" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 60700-3:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-10-03
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-01-03
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.
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 60700-3:2022 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 60071-5 NOTE Harmonized as EN 60071-5
IEC 60099-4 NOTE Harmonized as EN 60099-4
IEC 60099-9 NOTE Harmonized as EN 60099-9
IEC 60146-1-1 NOTE Harmonized as EN 60146-1-1
IEC 60633 NOTE Harmonized as EN IEC 60633
IEC/TR 60919-1 NOTE Harmonized as CLC/TR 60919-1
IEC/TR 60919-2 NOTE Harmonized as CLC/TR 60919-2
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 60060-1 - High-voltage test techniques - Part 1: EN 60060-1 -
General definitions and test requirements
IEC 60071-1 - Insulation co-ordination - Part 1: EN IEC 60071-1 -
Definitions, principles and rules
IEC 60700-1 2015 Thyristor valves for high voltage direct EN 60700-1 2015
current (HVDC) power transmission - Part
1: Electrical testing
+ AMD1 2021 + A1 2021
IEC 60700-2 2016 Thyristor valves for high voltage direct EN 60700-2 2016
current (HVDC) power transmission - Part
2: Terminology
IEC 61803 2020 Determination of power losses in high- EN IEC 61803 2020
voltage direct current (HVDC) converter
stations with line-commutated converters
IEC 60700-3 ®
Edition 1.0 2022-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thyristor valves for high voltage direct current (HVDC) power transmission –
Part 3: Essential ratings (limiting values) and characteristics
Valves à thyristors pour le transport d’énergie en courant continu à haute
tension (CCHT) –
Partie 3: Valeurs assignées (valeurs limites) et caractéristiques essentielles
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.200 ISBN 978-2-8322-6121-7
– 2 – IEC 60700-3:2022 © IEC 2022
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviated terms . 7
3.1 Terms and definitions . 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 Service conditions . 9
4.1 General . 9
4.2 Environmental conditions . 9
4.2.1 Site altitude . 9
4.2.2 Air temperature and humidity range in valve halls . 9
4.2.3 Cleanness in valve halls . 10
4.2.4 Seismic conditions . 10
4.3 System conditions . 10
4.3.1 General information of the system . 10
4.3.2 AC system voltage . 10
4.3.3 AC system frequency . 10
4.3.4 DC system voltage . 10
4.3.5 DC system current and overload requirements . 11
4.3.6 Short circuit current requirements for thyristor valves . 11
4.3.7 Insulation coordination design related to thyristor valves . 11
4.4 Technical parameters for six-pulse bridge design . 11
4.4.1 General . 11
4.4.2 Voltage parameters . 11
4.4.3 Current parameters. 12
4.4.4 Valve arrester parameters . 13
4.4.5 Other system parameters. 13
4.5 Other conditions. 14
5 Ratings . 14
5.1 Voltage and current ratings (limiting values) . 14
5.1.1 Rated AC voltage across valve (U ) . 14
v0N
5.1.2 Maximum steady state AC voltage across valve (U ) . 14
v0max
5.1.3 Maximum temporary state AC voltage across valve (U ) . 14
v0maxT
5.1.4 Minimum steady state AC voltage across valve (U ) . 15
v0min
5.1.5 Minimum temporary state AC voltage across valve (U ) . 15
v0minT
5.1.6 Valve repetitive peak off-state voltage (U ) . 15
vDRM
5.1.7 Valve non-repetitive peak off-state voltage (U ) . 15
vDSM
5.1.8 Valve repetitive peak reverse voltage (U ) . 15
vRRM
5.1.9 Valve non-repetitive peak reverse voltage (U ) . 15
vRSM
5.1.10 Valve switching impulse withstand voltage (SIWV ) . 15
v
IEC 60700-3:2022 © IEC 2022 – 3 –
5.1.11 Valve lightning impulse withstand voltage (LIWV ) . 16
v
5.1.12 Valve steep front impulse withstand voltage (STIWV ) . 16
v
5.1.13 Valve switching impulse protective firing voltage (SIPL ) . 16
PF
5.1.14 Valve RMS current (I ) . 16
v(RMS)
5.1.15 Valve average current (I ) . 16
v(av)
5.1.16 Valve one-loop fault current with re-applied forward voltage (I ) . 16
SCα
5.1.17 Valve multiple-loop fault current without re-applied forward voltage
(I ) . 17
SCβ
5.2 Delay and extinction angle ratings (limiting values) . 17
5.2.1 Rated firing delay angle (α ) . 17
N
5.2.2 Minimum allowable firing delay angle (α ) . 17
min
5.2.3 Maximum allowable firing delay angle (α ) . 17
max
5.2.4 Minimum temporary state firing delay angle (α ) . 17
minT
5.2.5 Rated extinction angle (γ ) . 17
N
5.2.6 Minimum allowable extinction angle (γ ). 17
min
5.2.7 Maximum allowable extinction angle (γ ) . 17
max
5.2.8 Minimum temporary state extinction angle (γ ) . 17
minT
5.3 Insulation and test voltage levels (limiting values) . 18
5.3.1 Maximum DC voltage between valve terminals (U ) . 18
d(v)max
5.3.2 Maximum DC voltage across multiple valve unit (U ) . 18
d(m)max
5.3.3 Maximum DC voltage across valve support (U ) . 18
d(vs)max
5.3.4 Maximum AC voltage between valve terminals (U ) . 18
ac(v)max
5.3.5 Maximum AC voltage across multiple valve unit (U ) . 19
ac(m)max
5.3.6 Maximum AC voltage across valve support (U ) . 19
ac(vs)max
5.3.7 Maximum switching impulse voltage between valve terminals
(U ). 19
s(v)max
5.3.8 Maximum switching impulse voltage across multiple valve unit
(U ) . 19
s(m)max
5.3.9 Maximum switching impulse voltage across valve support (U ) . 20
s(vs)max
5.3.10 Maximum lightning impulse voltage between valve terminals (U ) . 20
l(v)max
5.3.11 Maximum lightning impulse voltage across multiple valve unit
(U ) . 20
l(m)max
5.3.12 Maximum lightning impulse voltage across valve support (U ) . 20
l(vs)max
5.3.13 Maximum steep front impulse voltage between valve terminals
(U ) . 20
st(v)max
5.3.14 Maximum steep front impulse voltage across multiple valve unit
(U ) . 21
st(m)max
5.3.15 Maximum steep front impulse voltage across valve support
(U ) . 21
st(vs)max
6 Characteristics . 21
6.1 General . 21
6.2 Losses characteristics . 21
6.2.1 General . 21
6.2.2 Maximum load loss per valve at rated condition (P ) . 21
vmax
– 4 – IEC 60700-3:2022 © IEC 2022
6.2.3 Maximum no-load loss per valve (P ) . 22
v0max
6.2.4 Maximum heat emission to valve hall (P ) . 22
Emax
6.3 Protection characteristics . 22
6.3.1 Valve lightning impulse protective firing voltage (LIPL ) . 22
PF
6.3.2 Valve steep front impulse protective firing voltage (STIPL ) . 22
PF
6.3.3 Thyristor protective firing level (V ) . 22
PF
6.3.4 Thyristor forward recovery protection level (V ) . 22
RP
6.3.5 Thyristor forward du/dt protection level (du/dt ) . 22
PF
6.3.6 Valve protective firing trip level (N ) . 23
tripPF
6.3.7 Valve loss of redundancy trip level (N ) . 23
trip
6.4 Temperature characteristics . 23
6.4.1 Maximum cooling medium temperature at valve inlet (T ) . 23
(in)max
6.4.2 Maximum cooling medium temperature at valve outlet (T ) . 23
(out)max
6.4.3 Thyristor junction temperature at rated condition (T ) . 23
jN
6.4.4 Maximum thyristor junction temperature (T ) . 23
jmax
6.4.5 Storage temperature (T ) . 23
stg
6.5 Reliability characteristics . 23
6.5.1 General . 23
6.5.2 Expected annual failure rate of thyristor level (λ ) . 24
E
6.6 Other characteristics . 24
6.6.1 Valve on-state voltage (U ) . 24
v(on)
6.6.2 Maximum steady state operating time at α = 90° (t ) . 24
90max
6.6.3 Maximum temporary state operating time at α = 90° (t ) . 24
90maxT
6.6.4 Maximum steady state commutation overshoot factor (k ) . 24
c
6.6.5 Maximum temporary state commutation overshoot factor (k ) . 24
cT
Annex A (informative) Input parameters for thyristor valve design . 29
Annex B (informative) Technical data sheet of thyristor valves . 31
Bibliography . 34
Figure 1 – Typical arrester arrangement for converter units with two 12-pulse bridges
in series . 25
Figure 2 – Operating voltage of valve and valve arrester in rectified mode . 26
Figure 3 – Thyristor valve voltage waveforms in different operation modes . 26
Figure 4 – One loop valve short circuit current and voltage waveforms . 27
Figure 5 – Multiple loop valve short circuit current and voltage waveforms . 27
Figure 6 – Continuous operating voltages at various locations for a 12-pulse bridge in
rectifier mode . 28
Table A.1 – Main input parameters required for thyristor valve design . 29
Table B.1 – Technical data sheet of thyristor valves . 31
IEC 60700-3:2022 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THYRISTOR VALVES FOR HIGH VOLTAGE DIRECT CURRENT (HVDC)
POWER TRANSMISSION –
Part 3: Essential ratings (limiting values) and characteristics
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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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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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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 60700-3 has been prepared by subcommittee 22F: Power electronics for electrical
transmission and distribution systems, of IEC technical committee 22: Power electronic systems
and equipment. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
22F/667/CDV 22F/686/RVC
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.
– 6 – IEC 60700-3:2022 © IEC 2022
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/publications.
A list of all parts in the IEC 60700 series, published under the general title Thyristor valves for
high voltage direct current (HVDC) power transmission, can be found on the IEC website.
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.
IEC 60700-3:2022 © IEC 2022 – 7 –
THYRISTOR VALVES FOR HIGH VOLTAGE DIRECT CURRENT (HVDC)
POWER TRANSMISSION –
Part 3: Essential ratings (limiting values) and characteristics
1 Scope
This part of IEC 60700 specifies the service conditions, the definitions of essential ratings and
characteristics of thyristor valves utilized in line commutated converters with three-phase bridge
connections to realize the conversion from AC to DC and vice versa for high voltage direct
current (HVDC) power transmission applications. It is applicable for air insulated, liquid cooled
and indoor thyristor valves.
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.
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power
transmission – Part 1: Electrical testing
IEC 60700-1:2015/AMD1:2021
IEC 60700-2:2016, Thyristor valves for high voltage direct current (HVDC) power
transmission – Part 2: Terminology
IEC 61803:2020, Determination of power losses in high-voltage direct current (HVDC) converter
stations with line-commutated converters
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
___________
There exists a consolidated edition 1.1 (2021) that comprises IEC 60700-1:2015 and its Amendment 1:2021.
– 8 – IEC 60700-3:2022 © IEC 2022
3.2 Symbols and abbreviated terms
3.2.1 General
Clause 3.2 covers only the most frequently used symbols and abbreviated terms related to this
document. The documents listed in Clause 2 contain additional symbols and abbreviated terms.
3.2.2 Subscripts
0 (zero) at no load
i ideal
N nominal or rated value
d direct current or voltage
ac alternating current or voltage
r resistive or overvoltage
x inductive
u undervoltage
j thyristor junction
v valve or valve side of converter transformer
m multiple valve (unit)
vs valve support
s switching impulse or stray
l lightning impulse
st steep front impulse
PF protective firing
RP recovery protection
T temporary
S short term
SC short circuit
max maximum
min minimum
RMS root mean square
av average
ar arrester
DRM off-state repetitive maximum value
DSM off-state non-repetitive maximum value
RRM reverse repetitive maximum value
RSM reverse non-repetitive maximum value
3.2.3 Letter symbols
α (trigger/firing) delay angle
γ extinction angle
μ (commutation) overlap angle
X commutation circuit reactance, including leakage reactance of converter
t
transformer and other reactance in the commutation circuit which influence
commutation process
IEC 60700-3:2022 © IEC 2022 – 9 –
P on-load losses of converter transformer and DC smoothing reactor when a six-pulse
cu
bridge is operating at rated load
equivalent resistance of the voltage drop of the thyristor valve
R
th
f rated AC system frequency
N
t valve conduction interval
p
t valve hold-off interval
G
k uneven voltage distribution factor, defined as the maximum deviation of the peak
df
voltages of thyristor levels in a valve under the specified type of impulses,
representing the degree of uneven voltage distribution due to tolerances of the
voltage divider components, stray capacitances and differences in recovery charge
of thyristors
3.2.4 Abbreviated terms
MVU multiple valve (unit)
SIPL switching impulse protective level
LIPL lightning impulse protective level
STIPL steep front impulse protective level
4 Service conditions
4.1 General
Thyristor valves shall be able to operate continuously and reliably under the specified service
conditions throughout their entire service life except for maintenance periods. Such conditions,
as the main input parameters for valve design, are essential to define the ratings and
characteristics of the thyristor valves, and should be specified by the purchaser or by the system
designer or the supplier as recommended in Annex A. The conditions mainly include the
environmental conditions of valve halls under which thyristor valves will be required to operate,
system conditions directly related to the design and operation of thyristor valves, main technical
parameters of six-pulse bridges required by the system design, and any other conditions
provided by the purchaser. Some of these conditions cannot be applicable depending upon the
HVDC system design.
4.2 Environmental conditions
4.2.1 Site altitude
The altitude of the HVDC substation above sea-level shall be provided for insulation design of
thyristor valves.
For external insulation (as defined in 3.1.3 of IEC 60700-1:2015), the insulation level of thyristor
valves under standardized reference atmospheric conditions shall be determined in accordance
with 4.2 of IEC 60700-1:2015.
For internal insulation (as defined in 3.1.3 of IEC 60700-1:2015), 8.2 of IEC 60700-1:2015 shall
be referred to.
4.2.2 Air temperature and humidity range in valve halls
The maximum temperature and minimum relative humidity inside valve halls shall be considered
in the atmospheric correction in accordance with 4.2 of IEC 60700-1:2015. In addition, the air
temperature and the relative humidity in the valve hall shall be considered to prevent
condensation on any surface of components within the valve hall.
– 10 – IEC 60700-3:2022 © IEC 2022
4.2.3 Cleanness in valve halls
The cleanness in valve halls (e.g. equivalent salt deposit density on the surface of insulators
and insulating materials) shall be provided for determination of creepage distances of thyristor
valves. Dust and pollution in valve halls shall be kept as low as possible to avoid un-economical
increase of creepage distances of thyristor valves.
4.2.4 Seismic conditions
Thyristor valves shall have the ability to withstand seismic stresses and to maintain their
function without failure during and after an earthquake of any specified intensity possibly
occurring at the location of the HVDC substation. Maximum expected horizontal and vertical
acceleration along with the frequency range of oscillations shall be provided.
4.3 System conditions
4.3.1 General information of the system
The information shall include at least the following:
a) the purpose of the project,
b) rated power,
c) direction of power flow,
d) converter configuration, including a simple one-line diagram,
e) converter operating modes such as monopolar, bipolar, parallel or multi-terminal, and
f) interface information.
NOTE 1 For long distance HVDC transmission systems, the most commonly used converter unit configuration is
one 12-pulse group per pole or two 12-pulse groups in series connection or parallel connection per pole. Each valve
group is composed of two series-connected six-pulse bridges that are supplied from three single-phase three-winding
transformers or six single-phase two-winding transformers. For more details on converter unit configuration, refer to
IEC TR 60919-1.
NOTE 2 The interfaces between the thyristor valves and other components of the system need to be coordinated,
including the location and dimensions of points of attachment on the floor of the valve hall or to the roof, dimensions
of cable ducts for fibre optic cable, the location and dimensions of the connecting flange for cooling water pipes, and
the interfaces to valve-hall buswork.
4.3.2 AC system voltage
The steady state and temporary state AC system voltage ranges shall be specified, including
the maximum and minimum steady state voltages under rated operating condition, as well as
the maximum and minimum temporary state voltages along with their durations during AC
system faults and during the recovery period immediately following fault clearing. The temporary
state AC system voltage range will directly affect the voltage ratings of thyristor valves.
4.3.3 AC system frequency
The rated frequency, steady state frequency variation range, temporary state frequency
variation range, as well as temporary state extreme frequency variation range shall be specified.
4.3.4 DC system voltage
The rated DC voltage, and the maximum and minimum DC voltages in continuous operation
considering control and measurement errors and manufacturing tolerance shall be specified.
If thyristor valves are required to operate continuously with reduced DC voltages, the DC system
voltages, along with the operating parameters of the thyristor valves, i.e. valve side winding
voltages and firing delay angles under these operating conditions, shall also be provided.
IEC 60700-3:2022 © IEC 2022 – 11 –
4.3.5 DC system current and overload requirements
The rated DC current and minimum DC currents in continuous operation, as well as the required
short term overload and temporary overload DC currents along with their durations shall be
specified.
4.3.6 Short circuit current requirements for thyristor valves
For converter units, short circuits can be caused by breakdown of external or internal insulation,
i.e. flashover or puncture of insulators, or by inadvertent operation of switches, or from other
causes. Usually the most severe fault is a short circuit of the thyristor valve operating in rectifier
mode with minimum delay angle and maximum AC system voltage. The maximum peak values
of one-loop and multiple-loop short circuit currents, along with their durations and the maximum
peak values of re-applied forward voltages and reverse recovery voltages that the thyristor
valves are required to withstand, shall be specified.
4.3.7 Insulation coordination design related to thyristor valves
The required overvoltage withstand capability of thyristor valves, as well as the protective levels
(residual voltages and coordination currents for specified types of overvoltage) of valve
arresters, shall be specified, based on the insulation coordination design of the system.
A typical arrangement for the arresters directly related to the thyristor valves of a station
consisting of two series-connected 12-pulse converters per pole is shown in Figure 1. Some of
the arresters may be eliminated depending upon the specific design.
For thyristor valve design and test, the required withstand voltages for switching and lightning
impulses of the valves between the locations, as shown in Figure 1, shall be specified, including:
a) withstand voltages across a valve,
b) withstand voltages between the upper 12-pulse bridge DC bus and earth,
c) withstand voltages between the upper 12-pulse bridge mid-point DC bus and earth,
d) withstand voltages between the two 12-pulse bridges mid-point DC bus and earth,
e) withstand voltages between the lower 12-pulse bridges mid-point DC bus and earth, and
f) withstand voltages between the neutral bus and earth.
For more details about the insulation coordination design refer to IEC 60071-5.
NOTE Valve arrester design is one unseparated part of thyristor valve design for an optimized converter. Defining
the withstand voltages across a valve without considering the interaction between valve and valve arrester always
leads to an uneconomic valve.
4.4 Technical parameters for six-pulse bridge design
4.4.1 General
The parameters described in 4.4 are related to converters comprised of six thyristor valves. The
values of these parameters shall be considered in the design of thyristor valves.
4.4.2 Voltage parameters
4.4.2.1 Rated DC voltage per converter (U )
dN
This refers to the mean value of DC voltage between the high voltage and low voltage terminals
of a converter (six-pulse bridge) under rated operating condition. It is defined at nominal valve
side winding voltage and nominal converter firing delay angle while operating at rated DC
current.
– 12 – IEC 60700-3:2022 © IEC 2022
4.4.2.2 Nominal ideal no-load DC voltage per converter (U )
di0N
This refers to the ideal no-load DC voltage of a converter at nominal valve side winding voltage,
idealized firing delay and overlap angles equalling zero.
4.4.2.3 Maximum ideal no-load DC voltage per converter (U )
di0max
This refers to the maximum value of ideal no-load DC voltage of a converter at nominal valve
side winding voltage, idealized firing delay and overlap angles equalling zero, taking into
account the control and measurement errors and manufacturing tolerance of the system.
)
4.4.2.4 Minimum ideal no-load DC voltage per converter (U
di0min
This refers to the minimum value of ideal no-load DC voltage of a converter at nominal valve
side winding voltage, idealized firing and overlap angles equalling zero, taking into account the
control and measurement errors and manufacturing tolerance of the system.
4.4.2.5 Temporary overvoltage factor (k )
r
This refers to the factor defined as the ratio of maximum temporary state AC system voltage
during AC system faults, such as load rejection, to nominal AC system voltage.
4.4.2.6 Temporary undervoltage factor (k )
u
This refers to the factor defined as the ratio of minimum temporary state AC system voltage
during AC system faults, such as single-phase or three-phase short circuits to ground, to
nominal AC system voltage.
4.4.3 Current parameters
4.4.3.1 Rated DC current (I )
dN
This refers to the nominal value of direct current that the system should be able to transmit
continuously for all ambient conditions specified and without time limitations.
4.4.3.2 Maximum continuous operating DC current (I )
dmax
This refers to the maximum value of direct current that the system should be able to transmit
continuously without time limitations. The current value may vary under different ambient
conditions and different cooling conditions.
4.4.3.3 Minimum continuous operating DC current (I )
dmin
This refers to the minimum value of direct current that the system should be able to transmit
continuously without time limitations. It is defined to avoid the intermittent direct current for
steady state operation. A value of 5 % to 10 % of rated DC current is commonly used.
4.4.3.4 Short term overload DC current (I )
dS
This refers to the maximum value of direct current that the system should be able to transmit
under specified short term overload conditions, typically in the time span from minutes up to
hours. The current value may vary under different ambient conditions, different durations and
different cooling conditions.
4.4.3.5 Temporary overload DC current (I )
dT
This refers to the maximum value of direct current that the system should be able to transmit
under specified temporary overload conditions, typically in the range of seconds.
IEC 60700-3:2022 © IEC 2022 – 13 –
4.4.4 Valve arrester parameters
4.4.4.1 Crest value of continuous operating voltage (CCOV)
This refers to the highest continuously occurring crest value of the voltage across the arrester
excluding commutation overshoots and commutation notches. The continuous operating voltage
waveform for the valve and valve arrester is shown in Figure 2. The CCOV is proportional to
the maximum ideal no-load DC voltage per converter (U ), and is given by Formula (1):
di0max
π
CCOV ⋅U (1)
di0max
4.4.4.2 Peak value of continuous operating voltage (PCOV)
This refers to the highest continuously occurring peak value of the voltage across the arrester
including commutation overshoots and commutation notches.
See Figure 2.
4.4.4.3 Switching impulse protective level of valve arrester (SIPL )
v
This refers to the residual arrester voltage for maximum switching current impulse possibly
occurring in service.
4.4.4.4 Lightning impulse protective level of valve arrester (LIPL )
v
This refers to the residual arrester voltage for maximum lightning current impulse possibly
occurring in service.
4.4.4.5 Steep front impulse protective level of valve arrester (STIPL )
v
This refers to the residual arrester voltage for maximum steep front current impulse possibly
occurring in service.
4.4.4.6 Maximum surge arrester commutation current （I ）
ar
This refers to the maximum peak value of the surge arrester coordination current that can be
flowing in the forward direction at the time the valve turns on. Due to the commutation of the
arrester current, the thyristors and their associated electrical circuits shall withstand the
maximum turn-on current stress under the specified high voltage conditions.
4.4.5 Other system parameters
4.4.5.1 Rated relative inductive DC voltage drop (d )
xN
This refers to the maximum and minimum values of the relative inductive DC voltage drop of a
converter under rated operating condition, which can be calculated with Formula (2).
XI⋅
t dN
d ⋅
(2)
xN
π U
di0N
=
=
– 14 – IEC 60700-3:2022 © IEC 2022
4.4.5.2 Rated relative resistive DC voltage drop (d )
...
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