Terminology for voltage-sourced converters (VSC) for high-voltage direct current (HVDC) systems

IEC 62747:2014 defines terms for the subject of self-commutated voltage-sourced converters used for transmission of power by high voltage direct current (HVDC). The standard is written mainly for the case of application of insulated gate bipolar transistors (IGBTs) in voltage sourced converters (VSC) but may also be used for guidance in the event that other types of semiconductor devices which can both be turned on and turned off by control action are used. Line-commutated and current-sourced converters for high-voltage direct current (HVDC) power transmission systems are specifically excluded from this standard.

Terminologie für Spannungszwischenkreis-Stromrichter (VSC) für Hochspannungsgleichstrom(HGÜ)-Systeme

Terminologie relative aux convertisseurs de source de tension (VSC) des systèmes en courant continu à haute tension (CCHT)

L'IEC 62747:2014 définit les termes relatifs aux convertisseurs de source de tension autocommutés utilisés pour le transport d'énergie en courant continu à haute tension (CCHT). La norme a été essentiellement élaborée pour l'application des transistors bipolaires à grille isolée (IGBT) des convertisseurs de source de tension (VSC), mais elle peut également être utilisée comme guide en cas d'utilisation d'autres dispositifs à semiconducteur pouvant être activés ou désactivés par une action de commande. Les convertisseurs commutés par le réseau et les convertisseurs à source de courant des systèmes de transport d'énergie en courant continu à haute tension (CCHT) sont exclus de la présente norme.

Terminologija za napetostne pretvornike (VSC) za visokonapetostne enosmerne sisteme (IEC 62747:2014)

Standard EN IEC 62747 določa izraze za predmet napetostnih pretvornikov z lastno komutacijo, ki se uporabljajo za prenos moči z visokonapetostnim enosmernim tokom (HVDC). Ta standard je napisan zlasti za primer uporabe bipolarnih tranzistorjev z izoliranimi vrati (IGBT) v napetostnih pretvornikih (VSC), vendar se lahko uporablja tudi za navodila v primeru, da se uporabljajo druge vrste polprevodniških naprav, ki jih je s kontrolnim ukrepom mogoče vklopiti in izklopiti. Pretvorniki z linijsko komutacijo in tokovni pretvorniki za visokonapetostne enosmerne sisteme za prenos moči so izrecno izključeni iz tega standarda.

General Information

Status
Published
Publication Date
18-Sep-2014
Technical Committee
Drafting Committee
Current Stage
6060 - Document made available
Due Date
19-Sep-2014
Completion Date
19-Sep-2014

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SLOVENSKI STANDARD
SIST EN 62747:2014
01-november-2014
Terminologija za napetostne pretvornike (VSC) za visokonapetostne enosmerne
sisteme (IEC 62747:2014)

Terminology for voltage-sourced converters (VSC) for high-voltage direct current (HVDC)

systems

Terminologie relative aux convertisseurs de source de tension (VSC) des systèmes en

courant continu à haute tension (CCHT)
Ta slovenski standard je istoveten z: EN 62747:2014
ICS:
01.040.29 Elektrotehnika (Slovarji) Electrical engineering
(Vocabularies)
29.200 8VPHUQLNL3UHWYRUQLNL Rectifiers. Convertors.
6WDELOL]LUDQRHOHNWULþQR Stabilized power supply
QDSDMDQMH
SIST EN 62747:2014 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 62747:2014
---------------------- Page: 2 ----------------------
SIST EN 62747:2014
EUROPEAN STANDARD EN 62747
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2014
ICS 29.200; 29.240
English Version
Terminology for voltage-sourced converters (VSC) for high-
voltage direct current (HVDC) systems
(IEC 62747:2014)

Terminologie relative aux convertisseurs de source de Terminologie für Spannungszwischenkreis-Stromrichter

tension (VSC) des systèmes en courant continu à haute (VSC) für Hochspannungsgleichstrom(HGÜ)-Systeme

tension (CCHT) (IEC 62747:2014)
(CEI 62747:2014)

This European Standard was approved by CENELEC on 2014-08-21. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 62747:2014 E
---------------------- Page: 3 ----------------------
SIST EN 62747:2014
EN 62747:2014 - 2 -
Foreword

The text of document 22F/301/CDV, future edition 1 of IEC 62747, 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 62747:2014.
The following dates are fixed:
– latest date by which the document has to be implemented at (dop) 2015-05-21
national level by publication of an identical national
standard or by endorsement
– latest date by which the national standards conflicting with (dow) 2017-08-21
the 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 [and/or CEN] shall not be held responsible for identifying any or all such

patent rights.
Endorsement notice

The text of the International Standard IEC 62747:2014 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 standards indicated:

IEC 60146-1-1 NOTE Harmonized as EN 60146-1-1.
IEC 60146-2 NOTE Harmonized as EN 60146-2.
IEC 60747 NOTE Harmonized in EN 60747 series.
IEC 60633 NOTE Harmonized as EN 60633.
IEC 62501 NOTE Harmonized as EN 62501.
IEC 62751-1 NOTE Harmonized as EN 62751-1 .
IEC 62751-2 NOTE Harmonized as EN 62751-2 .
1) To be published.
---------------------- Page: 4 ----------------------
SIST EN 62747:2014
- 3 - EN 62747:2014
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When 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 60027 series Letter symbols to be used in electrical EN 60027 series
technology
IEC 60617 - Graphical symbols for diagrams - -
---------------------- Page: 5 ----------------------
SIST EN 62747:2014
---------------------- Page: 6 ----------------------
SIST EN 62747:2014
IEC 62747
Edition 1.0 2014-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Terminology for voltage-sourced converters (VSC) for high-voltage direct
current (HVDC) systems
Terminologie relative aux convertisseurs de source de tension (VSC) des
systèmes en courant continu à haute tension (CCHT)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX V
ICS 29.200; 29.240 ISBN 978-2-8322-1702-3

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
---------------------- Page: 7 ----------------------
SIST EN 62747:2014
– 2 – IEC 62747:2014  IEC 2014
CONTENTS

FOREWORD ......................................................................................................................... 3

1  Scope ............................................................................................................................ 5

2  Normative references..................................................................................................... 5

3  Symbols and abbreviations ............................................................................................ 5

3.1  List of letter symbols ............................................................................................. 5

3.2  List of subscripts ................................................................................................... 6

3.3  List of abbreviations .............................................................................................. 7

4  Graphical symbols ......................................................................................................... 8

5  General terms related to converter circuits ..................................................................... 9

6  VSC topologies ............................................................................................................ 10

7  Converter units and valves ........................................................................................... 10

8  Converter operating conditions..................................................................................... 16

9  HVDC systems and substations ................................................................................... 20

10  HVDC substation equipment ........................................................................................ 23

11  Modes of control .......................................................................................................... 26

12  Control systems ........................................................................................................... 27

Bibliography .................................................................................................................. ..... 30

Figure 1 – Converter symbol identifications ........................................................................... 7

Figure 2 – Graphical symbols ................................................................................................ 8

Figure 3 – Voltage-sourced converter unit ........................................................................... 11

Figure 4 – Phase unit of the modular multi-level converter (MMC) in basic half-bridge,

two-level arrangement, with submodules ............................................................................. 13

Figure 5 – Phase unit of the cascaded two-level converter (CTL) in half-bridge form ............ 14

Figure 6 – Phasor diagram showing a.c. system voltage, converter a.c. voltage and

converter a.c. current ........................................................................................................ .. 18

Figure 7 – Example of bipolar VSC transmission with earth return ........................................ 21

Figure 8 – VSC transmission with a symmetrical monopole illustrated with capacitive

earthing on the d.c. side ...................................................................................................... 22

Figure 9 – VSC transmission with an asymmetrical monopole with metallic return ................ 22

Figure 10 – VSC transmission with an asymmetrical monopole with earth return .................. 22

Figure 11 – Major components that may be found in a VSC substation ................................. 25

Figure 12 – Hierarchical structure of an HVDC control system ............................................. 29

---------------------- Page: 8 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TERMINOLOGY FOR VOLTAGE-SOURCED CONVERTERS (VSC)
FOR HIGH-VOLTAGE DIRECT CURRENT (HVDC) SYSTEMS
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, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising 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

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

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.

International Standard IEC 62747 has been prepared by subcommittee 22F: Power

electronics for electrical transmission and distribution systems, of IEC technical committee 22:

Power electronic systems and equipment.
The text of this standard is based on the following documents:
CDV Report on voting
22F/301/CDV 22F/317A/RVC

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 9 ----------------------
SIST EN 62747:2014
– 4 – IEC 62747:2014  IEC 2014

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct
contents. Users should therefore print this document using a
understanding of its
colour printer.
---------------------- Page: 10 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 5 –
TERMINOLOGY FOR VOLTAGE-SOURCED CONVERTERS (VSC)
FOR HIGH-VOLTAGE DIRECT CURRENT (HVDC) SYSTEMS
1 Scope

This International Standard defines terms for the subject of self-commutated voltage-sourced

converters used for transmission of power by high voltage direct current (HVDC).

The standard is written mainly for the case of application of insulated gate bipolar transistors

(IGBTs) in voltage sourced converters (VSC) but may also be used for guidance in the event

that other types of semiconductor devices which can both be turned on and turned off by

control action are used.

Line-commutated and current-sourced converters for high-voltage direct current (HVDC)

power transmission systems are specifically excluded from this standard.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60617, Graphical symbols for diagrams
3 Symbols and abbreviations
3.1 List of letter symbols

Essential terms and definitions necessary for the understanding of this standard are given

here; other terminology is as per relevant parts of IEC 60747.

The list covers only the most frequently used symbols (see Figure 1). IEC 60027 shall be

used for a more complete list of the symbols which have been adopted for static converters.

See also other standards listed in the normative references and the bibliography.

U direct voltage
U converter d.c. voltage
U pole-to-earth direct voltage
dpe
U pole-to-pole direct voltage
dpp
U rated pole-to-pole direct voltage
dppN
U rated pole-to-earth direct voltage
dpeN

U line-to-line voltage on line side of interface transformer, r.m.s. value including

harmonics
---------------------- Page: 11 ----------------------
SIST EN 62747:2014
– 6 – IEC 62747:2014  IEC 2014

U line-to-earth voltage on line side of interface transformer, r.m.s. value including

harmonics
U rated value of U
LN L

U line-to-line voltage on valve side of interface transformer, r.m.s. value including

harmonics

U line-to-earth voltage on valve side of interface transformer, r.m.s. value including

harmonics
U line-to-line converter voltage, r.m.s. value including harmonics

NOTE U is equal to U minus the voltage drop across the phase and valve reactors. However, U has only a

c v c
clear meaning during balanced conditions (steady state).
U line-to-earth converter voltage , r.m.s. value including harmonics
U voltage between terminals of a valve (any defined value)
valve
I direct current (any defined value)
I rated direct current

I current on line side of interface transformer, r.m.s. value including harmonics

I rated value of I
LN L

I current on valve side of interface transformer, r.m.s. value including harmonics

I current through a valve
νalve
3.2 List of subscripts
0 (zero) at no load
e earth
p pole
N rated value or at rated load
d direct current or voltage
L line side of interface transformer
c converter
v valve side of interface transformer
valve through or across one valve
max maximum
min minimum
n pertaining to harmonic component of order n
---------------------- Page: 12 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 7 –
Positive d.c. terminal
I I
valve d
valve
U U U
Le ve dpe
L I
dpp
transformer transformer
line side valve side
valve
Negative d.c. terminal
IEC
Figure 1 – Converter symbol identifications
3.3 List of abbreviations
The following abbreviations are always in capital letters and without dots.
CTL cascaded two-level converter
ERTB earth return transfer breaker
ESCR effective short-circuit ratio
FWD free-wheeling diode
HF high frequency
HVDC high-voltage direct current
IGBT insulated gate bipolar transistor
MMC modular multilevel converter
MRTB metallic return transfer breaker
MTDC multi-terminal HVDC transmission system
MVU multiple valve (unit)
NBS neutral bus switch
NGBS neutral bus grounding switch
PCC point of common coupling
PCC-DC point of common coupling – d.c. side
---------------------- Page: 13 ----------------------
SIST EN 62747:2014
– 8 – IEC 62747:2014  IEC 2014
SCR short-circuit ratio
VBE valve base electronics
VCU valve control unit
VSC voltage-sourced converter

NOTE Even though the word “breaker” is used in the abbreviations, it does not necessarily imply the ability to

interrupt fault currents.
4 Graphical symbols

Figure 2 shows the specific graphical symbols which are defined only for the purposes of this

standard. IEC 60617 shall be used for a more complete list of the graphical symbols which

have been adopted for static converters.
IEC
Figure 2 – Graphical symbols
---------------------- Page: 14 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 9 –
5 General terms related to converter circuits
5.1
conversion

in the context of HVDC, the transfer of energy from a.c. to d.c. or vice versa, or a combination

of these operations
5.2
converter

in the context of HVDC, the device employed to transfer of energy from a.c. to d.c. or vice

versa, it connects between three a.c. terminals and two d.c. terminals
5.3
voltage-sourced converter
VSC

electronic a.c./d.c. converter having an essentially smooth d.c. voltage provided by e.g. a

common d.c. link capacitor or distributed d.c. capacitors within the converter arms

5.4
arm
converter arm

part of a converter connecting the a.c. phase terminal with the d.c. pole terminal

5.5
commutation

transfer of current between any two paths with both paths carrying current simultaneously

during this process
5.6
line commutation

method of commutation whereby the commutating voltage is supplied by the a.c. system

5.7
self-commutation

commutation where the commutating voltage is supplied by components within the converter

or the electronic switch
5.8
commutating voltage

voltage which causes the current to commutate, provided either by the system or by a

switching action of valve/semiconductor devices
5.9
commutation inductance

total inductance included in the commutation circuit, in series with the commutating voltage

Note 1 to entry: The commutation inductance is typically referred as stray inductance or loop inductance.

5.10
coupling inductance

equivalent inductance referred to the converter side of the interface transformer between the

point of common coupling (PCC) and the d.c. terminal of the valve
---------------------- Page: 15 ----------------------
SIST EN 62747:2014
– 10 – IEC 62747:2014  IEC 2014
6 VSC topologies
6.1
two-level converter

converter in which the voltage between the a.c. terminals of the VSC unit (see 7.6) and VSC

unit midpoint (see 7.28) is switched between two discrete d.c. voltage levels
6.2
three-level converter

converter in which the voltage between the a.c. terminals of the VSC unit (see 7.6) and VSC

unit midpoint (see 7.28) is switched between three discrete d.c. voltage levels
6.3
multi-level converter

converter in which the voltage between the a.c. terminals of the VSC unit (see 7.6) and VSC

unit midpoint (see 7.28) is switched between more than three discrete d.c. voltage levels

6.4
modular multi-level converter
MMC

multi-level converter in which each VSC valve (see 7.8, 7.9) consists of a number of MMC

building blocks (see 7.11) connected in series
Note 1 to entry: See also Figure 4.
6.5
cascaded two-level converter
CTL

modular multi-level converter in which each switch position consists of more than one IGBT-

diode pair connected in series
Note 1 to entry: See Figure 5.
7 Converter units and valves
7.1
turn-off semiconductor device

controllable semiconductor device which may be turned on and off by a control signal, for

example an IGBT
7.2
insulated gate bipolar transistor
IGBT

turn-off semiconductor device with three terminals: a gate terminal (G) and two load terminals

emitter (E) and collector (C)
7.3
free-wheeling diode
FWD
power semiconductor device with diode characteristic
Note 1 to entry: A FWD has two terminals: an anode (A) and a cathode (K).

Note 2 to entry: The current through FWDs is in the opposite direction to the IGBT current.

7.4
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
---------------------- Page: 16 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 11 –

Note 1 to entry: An IGBT-diode pair is usually in one common package, however, it can include individual IGBTs

and/or diodes packages connected in parallel.
7.5
converter unit

indivisible operative unit comprising all equipment between the point of common coupling on

the a.c. side (see 9.25) and the point of common coupling – d.c. side (see 9.26), essentially

one or more VSC units, together with one or more interface transformers, converter unit

control equipment, essential protective and switching devices and auxiliaries, if any, used for

conversion
Note 1 to entry: See Figure 3.
7.6
VSC unit

three VSC phase units, together with VSC unit control equipment, essential protective and

switching devices, d.c. storage capacitors, phase reactors and auxiliaries, if any, used for

conversion
Note 1 to entry: See Figure 3.
7.7
VSC phase unit
equipment used to connect the two d.c. terminals to one a.c. terminal

Note 1 to entry: In the simplest implementation, the VSC phase unit consists of two VSC valves, and in some

case, it may include also valve reactors. The VSC phase unit may also include control and protection equipment,

and other components.
7.8
VSC valve

arrangement of IGBT-diode pairs connected in series and arranged to be

switched simultaneously as a single function unit
VSC valveVSC valve VSC valveVSC valve VSC valveVSC valve
D.c.
capacitor
ValveValve ValveValve ValveValve
reactorsreactors reactorsreactors reactorsreactors
PhasePhase PhasePhase PhasePhase
reactorreactor reactorreactor reactorreactor
VSC valveVSC valve VSC valveVSC valve VSC valveVSC valve
Phase PhasePhase PhasePhase
unit unitunit unitunit
D.c. Protective Dynamic
Converter control
capacitor devices braking valve
IEC
Figure 3 – Voltage-sourced converter unit

Note 1 to entry: In some designs of VSC, the phase reactors may fulfill part of the function of the converter-side

high frequency filter. In addition, in some designs of VSC, part or all of the phase reactor may be built into the

three “phase units” of the VSC unit, as “valve reactors”.

Note 2 to entry: In some designs of VSC, the VSC d.c. capacitor may be partly or entirely distributed amongst the

three “phase units” of the VSC unit, where it is referred to as d.c. submodule capacitors.

Note 3 to entry: Valve and/or phase reactors shown above show optional configurations which may not be

included in all schemes.
---------------------- Page: 17 ----------------------
SIST EN 62747:2014
– 12 – IEC 62747:2014  IEC 2014

Note 4 to entry: Just a typical example of how a VSC unit could look like is shown in Figure 3, differences may

exist at all levels.
7.9
VSC valve

complete controllable voltage source assembly, which is

generally connected between one a.c. terminal and one d.c. terminal
7.10
VSC valve level
the smallest indivisible functional unit of VSC valve

Note 1 to entry: For any VSC valve in which IGBTs are connected in series and operated simultaneously, one

VSC valve level is one IGBT-diode pair including its auxiliaries (see Figure 4). For MMC type without IGBT-diode

pairs connected in series, one valve level is one submodule together with its auxiliaries (see Figure 5).

7.11
MMC building block

self-contained, two-terminal controllable voltage source together with d.c. capacitor(s) and

immediate auxiliaries, forming part of a MMC
7.12
switch position
semiconductor function which behaves as a single, indivisible switch

Note 1 to entry: A switch position may consist of a single IGBT-diode pair or, in the case of the Cascaded Two

Level converter, a series connection of multiple IGBT-diode pairs.
7.13
submodule

MMC building block where each switch position consists of only one IGBT-diode pair

Note 1 to entry: See Figure 4.
---------------------- Page: 18 ----------------------
SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 13 –
Valve
MMC building block
= Submodule
= VSC valve level
Switch
position
Valve
IEC
Figure 4 – Phase unit of the modular multi-level converter (MMC)
in basic half-bridge, two-level arrangement, with submodules
7.14
cell

MMC building block where each switch position consists of more than one IGBT-diode pair

connected in series
Note 1 to entry: See Figure 5.
---------------------- Page: 19 ----------------------
SIST EN 62747:2014
– 14 – IEC 62747:2014  IEC 2014
Valve
VSC valve level
MMC building block
= Cell
Switch
position
Valve
IEC

Figure 5 – Phase unit of the cascaded two-level converter (CTL) in half-bridge form

7.15
diode valve
semiconductor valve containing only diodes as the main semiconductor devices and

associated circuits and components if any, which might be used in some VSC topologies

7.16
diode valve level

part of a diode valve composed of a diode and associated circuits and components, if any

7.17
dynamic braking valve

complete controllable device assembly, which is used to control energy absorption in a

dynamic braking resistor
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SIST EN 62747:2014
IEC 62747:2014  IEC 2014 – 15 –
7.18
dynamic braking valve level

part of a dynamic braking valve comprising a turn-off semiconductor device and an associated

diode, or controllable switches and diodes connected in parallel, or turn-off semiconductor

devices and diodes connected to a half bridge arrangement, together with their immediate

auxiliaries, storage capacitor, if any
7.19
valve
VSC valve, dynamic braking valve or diode valve according to the context
7.20
redundant levels

the maximum number of series connected VSC valve levels or diode valve levels in a

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