IEC TR 62543:2011

High-voltage direct current (HVDC) power transmission using voltage sourced converters (VSC)

IEC/TR 62543:2011(E) gives general guidance on the subject of voltage-sourced converters used for transmission of power by high voltage direct current (HVDC). It describes converters that are not only voltage-sourced (containing a capacitive energy storage medium and where the polarity of d.c. voltage remains fixed) but also self-commutated, using semiconductor devices which can both be turned on and turned off by control action. The scope includes 2-level and 3-level converters with pulse-width modulation (PWM), along with multi-level converters, but excludes 2-level and 3-level converters operated without PWM, in square-wave output mode. HVDC power transmission using voltage sourced converters is known as "VSC transmission". The various types of circuit that can be used for VSC transmission are described in the report, along with their principal operational characteristics and typical applications. The overall aim is to provide a guide for purchasers to assist with the task of specifying a VSC transmission scheme. Line-commutated and current-sourced converters are specifically excluded from this report. This technical report cancels and replaces IEC/PAS 62543:2008 (Ed.1) which was published by IEC and CIGRÉ jointly, and combined with engineering experience.

General Information

• Status: Published
• Publication Date: 22-May-2017
• ICS: 29.200 - Rectifiers. Convertors. Stabilized power supply
• ICS: 29.240.99 - Other equipment related to power transmission and distribution networks
• Technical Committee: SC 22F - Power electronics for electrical transmission and distribution systems
• Drafting Committee: WG 19 - TC 22/SC 22F/WG 19
• Current Stage: DELPUB - Deleted Publication
• Start Date: 30-Mar-2022
• Completion Date: 25-Jun-2021

Relations

• Replaces: IEC PAS 62543:2008 - DC transmission using voltage sourced converters
• Effective Date: 05-Sep-2023
• Amended By: IEC TR 62543:2011/AMD2:2017 - Amendment 2 - High-voltage direct current (HVDC) power transmission using voltage sourced converters (VSC)
• Effective Date: 05-Sep-2023
• Amended By: IEC TR 62543:2011/AMD1:2013 - Amendment 1 - High-voltage direct current (HVDC) power transmission using voltage sourced converters (VSC)
• Effective Date: 05-Sep-2023
• Revised: IEC TR 62543:2022 - High-voltage direct current (HVDC) power transmission using voltage sourced converters (VSC)
• Effective Date: 05-Sep-2023

Overview

IEC TR 62543:2011 provides general guidance on High-Voltage Direct Current (HVDC) power transmission using Voltage-Sourced Converters (VSC). The technical report describes VSCs that contain capacitive energy storage, keep DC polarity fixed, and are self-commutated using semiconductor devices (e.g., IGBTs) that can be turned on and off by control action. It covers 2‑level and 3‑level converters operated with pulse‑width modulation (PWM) and multi‑level converters (including MMC topologies), while explicitly excluding square‑wave (non‑PWM) 2‑ and 3‑level converters, line‑commutated converters, and current‑sourced converters. The report is intended as a practical purchasing and specification guide for VSC transmission schemes.

Key Topics and Requirements

• Converter topologies: Descriptions of 2‑level, 3‑level (NPC), multi‑level and MMC configurations, their operating characteristics and valve designs.
• Power semiconductors & valve design: Guidance on semiconductor selection, transient and steady‑state current/voltage requirements, diode and switch behavior.
• Control and operation: Principles for active and reactive power control, operational modes (including black start capability), control system requirements and telecommunication needs between stations.
• System configurations: Monopole, bipolar and combined series/parallel arrangements for DC circuits and converter station layouts.
• Harmonics and filtering: Harmonic performance, a.c. and d.c. filtering design considerations and harmonic suppression methods for PWM and multi‑level converters.
• Performance & testing: Steady‑state and dynamic performance expectations, factory and commissioning tests, pre‑commissioning and system tests.
• Environmental & EMC: Guidance on audible noise, EMF, and electromagnetic compatibility considerations for VSC HVDC installations.
• Specification support: Annexes with functional specification advice and methods for determining valve power losses to help purchasers prepare technical requirements.

Applications and Users

• Who uses it: Transmission system operators, utilities, HVDC project engineers, procurement teams, OEMs of converters and power electronics, consultants specifying VSC HVDC projects.
• Typical applications: Point‑to‑point long‑distance links, offshore wind farm connections, grid interconnections, weak‑grid support and systems requiring fast reactive power control or black‑start capability.
• Practical value: Helps specify converter topology, control performance, testing regimes, and environmental/EMC requirements for reliable VSC HVDC delivery.

Related Standards

• Cancels and replaces IEC/PAS 62543:2008 (published jointly by IEC and CIGRÉ). For full implementation, users should consult IEC publication lists and relevant HVDC, insulation coordination and EMC standards when developing procurement and design documents.

Keywords: HVDC, VSC, voltage‑sourced converter, PWM, MMC, IGBT, reactive power control, harmonic filters, bipolar, monopole, commissioning.

Standards Content (Sample)

IEC/TR 62543 ®
Edition 1.0 2011-03
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
IEC/TR 62543:2011(E)
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IEC/TR 62543 ®
Edition 1.0 2011-03
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.200; 29.240.99 ISBN 978-2-88912-424-4

– 2 – TR 62543  IEC:2011(E)
CONTENTS
FOREWORD . 6

1 Scope . 8

2 Normative references . 8

3 Terms and definitions . 8

3.1 General . 8

3.2 Letter symbols . 9

3.3 Power semiconductor terms . 9

3.4 VSC topologies . 10
submodule d.c. capacitor . 12
3.5 VSC transmission . 12
3.6 Operating states . 14
3.7 Type tests . 15
3.8 Production tests . 15
3.9 Sample tests . 15
3.10 Insulation co-ordination terms . 16
3.11 Power losses . 16
4 VSC transmission overview . 17
4.1 Basic operating principles of VSC transmission . 17
4.1.1 The voltage sourced converter as a black box . 17
4.1.2 The principles of active and reactive power control . 18
4.1.3 Operating principles of a VSC transmission scheme . 19
4.1.4 Applications of VSC transmission . 20
4.2 Design life . 20
4.3 VSC transmission configurations . 20
4.3.1 General . 20
4.3.2 D.C. circuit configurations . 21
4.3.3 Monopole configuration . 21
4.3.4 Bipolar configuration . 22
4.3.5 Parallel connection of two converters . 22
4.3.6 Series connection of two converters . 23
4.3.7 Parallel and series connection of more than two converters . 23
4.4 Semiconductors for VSC transmission . 23

5 VSC transmission converter topologies . 25
5.1 General . 25
5.2 Converter topologies with VSC valves of “switch” type . 25
5.2.1 General . 25
5.2.2 Operating principle . 26
5.2.3 Topologies . 26
5.3 Converter topologies with VSC valves of the “controllable voltage source”
type . 29
5.3.1 General . 29
5.3.2 MMC topology with VSC levels in half-bridge topology . 30
5.3.3 MMC topology with VSC levels in full-bridge topology . 31
5.4 VSC valve design considerations . 32
5.4.1 Reliability and failure mode . 32
5.4.2 Current rating . 33

TR 62543  IEC:2011(E) – 3 –
5.4.3 Transient current and voltage requirements . 33

5.4.4 Diode requirements . 33

5.4.5 Additional design details . 34

5.5 Other converter topologies . 34

5.6 Other equipment for VSC transmission schemes . 35

5.6.1 General . 35

5.6.2 Power components of a VSC transmission scheme . 35

5.6.3 VSC substation circuit breaker . 35

5.6.4 A.C. system side harmonic filters . 35

5.6.5 Radio frequency interference filters . 36

5.6.6 Interface transformers and phase reactors . 36
5.6.7 Valve reactor . 37
5.6.8 D.C. capacitors . 37
5.6.9 D.C. reactor . 39
5.6.10 Common mode blocking reactor . 39
5.6.11 D.C. filter . 39
6 Overview of VSC controls . 39
6.1 General . 39
6.2 Operational modes and operational options . 40
6.3 Power transfer . 41
6.3.1 General . 41
6.3.2 Telecommunication between converter stations . 42
6.4 Reactive power and a.c. voltage control . 42
6.4.1 A.C. voltage control . 42
6.4.2 Reactive power control . 42
6.5 Black start capability . 43
6.6 Supply from a wind farm . 43
7 Steady state operation . 44
7.1 Steady state capability . 44
7.2 Converter power losses . 45
8 Dynamic performance . 45
8.1 A.C. system disturbances . 45
8.2 D.C. system disturbances . 46
8.2.1 D.C. cable fault . 46
8.2.2 D.C. overhead line fault . 46

8.3 Internal faults . 46
9 HVDC performance requirements . 47
9.1 Harmonic performance . 47
9.2 Wave distortion . 48
9.3 Fundamental and harmonics . 48
9.3.1 Three-phase 2-level VSC . 48
9.3.2 Selective harmonic elimination modulation . 50
9.3.3 Multi-pulse and multi-level converters . 51
9.4 Harmonic voltages on power systems due to VSC operation . 51
9.5 Design considerations for harmonic filters (a.c. side) . 52
9.6 D.C. side filtering . 52
10 Environmental impact . 52
10.1 General . 52

– 4 – TR 62543  IEC:2011(E)
10.2 Audible noise . 52

10.3 Electric and magnetic fields (EMF) . 53

10.4 Electromagnetic compatibility (EMC) . 53

11 Testing and commissioning . 54

11.1 General . 54

11.2 Factory tests . 54

11.2.1 Component tests . 54

11.2.2 Control system tests . 54

11.3 Commissioning tests / System tests . 55

11.3.1 General . 55
11.3.2 Precommissioning tests . 55
11.3.3 Subsystem tests . 55
11.3.4 System tests . 56
Annex A (informative) Functional specification requirements for VSC transmission
systems . 60
Annex B (informative) Determination of VSC valve power losses . 68
Bibliography . 77

Figure 1 – Major components that may be found in a VSC substation . 9
Figure 2 – Diagram of a generic voltage source converter (a.c. filters not shown) . 17
Figure 3 – The principle of active power control . 18
Figure 4 – The principle of reactive power control . 19
Figure 5 – A point-to-point VSC transmission scheme . 19
Figure 6 – VSC transmission with a symmetrical monopole . 21
Figure 7 – VSC transmission with an asymmetrical monopole with metallic return . 22
Figure 8 – VSC transmission with an asymmetrical monopole with earth return . 22
Figure 9 – VSC transmission in bipolar configuration . 22
Figure 10 – Parallel connection of two converter units . 23
Figure 11 – Symbol of a controllable switch and associated free-wheeling diode . 24
Figure 12 – Symbol of an IGBT . 24
Figure 13 – Diagram of a three-phase 2-level converter and associated a.c. waveform
for one phase. 26
Figure 14 – Single-phase a.c. output for 2-level converter with PWM switching at 21

times fundamental frequency . 27
Figure 15 – Diagram of a three-phase 3-level NPC converter and associated a.c.
waveform for one phase . 28
Figure 16 – Single-phase a.c. output for 3-level NPC converter with PWM switching at
21 times fundamental frequency . 29
Figure 17 – Electrical equivalent for a converter with VSC valves acting like a
controllable voltage source . 30
Figure 18 – VSC valve level arrangement and equivalent circuit in MMC topology in
half-bridge topology . 30
Figure 19 – Converter block arrangement with MMC topology in half-bridge topology . 31
Figure 20 – VSC valve level arrangement and equivalent circuit in MMC topology with
full-bridge topology . 32
Figure 21 – Typical SSOA for the IGBT . 33
Figure 22 – A 2-level VSC bridge with the IGBTs turned off . 33

TR 62543  IEC:2011(E) – 5 –
Figure 23 – Representing a VSC unit as an a.c. voltage of magnitude U and phase

angle δ behind reactance . 40

Figure 24 – Concept of vector control . 41

Figure 25 – VSC power controller . 41

Figure 26 – A.C. voltage controller . 42

Figure 27 – A typical simplified PQ diagram . 44

Figure 28 – Protection concept of a VSC substation. 47

Figure 29 – Waveforms for three-phase 2-level VSC . 49

Figure 30 – Voltage harmonics spectra of a 2-level VSC with carrier frequency at 21st

harmonic . 50
Figure 31 – Phase output voltage for selective harmonic elimination modulation
(SHEM) . 50
Figure 32 – Equivalent circuit at the PCC of the VSC . 51
Figure B.1 – On state voltage of an IGBT or free-wheeling diode . 69
Figure B.2 – Piecewise-linear representation of IGBT or FWD on-state voltage . 70
Figure B.3 – IGBT switching losses as a function of collector current . 73
Figure B.4 – Free-wheeling diode recovery loss as a function of current . 74

– 6 – TR 62543  IEC:2011(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC/TR 62543, which is a technical report, 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 present technical report cancels and replaces IEC/PAS 62543:2008 (Ed.1) which was
published by IEC and CIGRÉ jointly, and combined with engineering experience.
The present IEC/TR 62543 bears the edition number 1.

TR 62543  IEC:2011(E) – 7 –
The text of this technical report is based on the following documents:

Enquiry draft Report on voting

22F/230/DTR 22F/239A/RVC
Full information on the voting for the approval of this technical report 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.

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
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IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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A bilingual version of this publication may be issued at a later date.

– 8 – TR 62543  IEC:2011(E)
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

1 Scope
This technical report gives general guidance on the subject of voltage-sourced converters
used for transmission of power by high voltage direct current (HVDC). It describes converters
that are not only voltage-sourced (containing a capacitive energy storage medium and where

the polarity of d.c. voltage remains fixed) but also self-commutated, using semiconductor
devices which can both be turned on and turned off by control action. The scope includes
2-level and 3-level converters with pulse-width modulation (PWM), along with multi-level
converters, but excludes 2-level and 3-level converters operated without PWM, in square-
wave output mode.
HVDC power transmission using voltage sourced converters is known as “VSC transmission”.
The various types of circuit that can be used for VSC transmission are described in the report,
along with their principal operational characteristics and typical applications. The overall aim
is to provide a guide for purchasers to assist with the task of specifying a VSC transmission
scheme.
Line-commutated and current-sourced converters are specifically excluded from this report.
2 Normative references
The following referenced documents are indispensable for the application 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 60633, Terminology for high-voltage direct-current (HVDC) transmission
IEC 61975, High-voltage direct current (HVDC) installations – System tests
3 Terms and definitions
For the purpose of this document, the following definitions apply.

3.1 General
NOTE This report uses the terminology established by IEC 60633 and IEC 61803 for line-commutated HVDC.
Only terms which are specific to HVDC transmission using voltage sourced converters are defined in this clause.
Those terms that are either identical to or obvious extensions of IEC 60633 or IEC 61803 terminology have not
been defined.
To support the explanations, Figure 1 presents the basic diagram of a VSC system. Dependent on the converter
topology and the requirements in the project, some components can be omitted or can differ.

TR 62543  IEC:2011(E) – 9 –
~
DC line of
j
the second pole
=
k
a b c d e f g h i l m n o
IEC  567/11
Figure 1 – Major components that may be found in a VSC substation
b
a circuit breaker i VSC d.c. capacitor
b line side harmonic filter j d.c. harmonic filter
c
c line side high frequency filter k neutral point grounding branch
d
d interface transformer l d.c. reactor
d
e converter side harmonic filter m common mode blocking reactor
a d
f + g converter side high frequency filter n d.c. side high frequency filter
a b
g phase reactor o d.c. cable or overhead transmission line

h VSC unit
a
In some designs of VSC, the phase reactor may fulfil part of the function of the converter-side high frequency
filter. In addition, in some designs of VSC, part of or all of the phase reactor may be built into the three “Phase
units” of the VSC unit, as “Valve reactors”.
b
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 the d.c. submodule capacitors.
c
The location of the neutral point grounding branch may be different depending on the design of the VSC unit.
d
Not normally required for back-to-back systems.
3.2 Letter symbols
line-to-line a.c. voltage of the converter unit(s), r.m.s. value, including
U
conv
harmonics;
alternating current of the converter unit(s), r.m.s. value, including
I
conv
harmonics;
line-to-line a.c. voltage of the a.c. system, r.m.s. value, including
U
L
harmonics;
I alternating current of the a.c. system, r.m.s. value, including harmonics;
L
U d.c. line-to-line voltage of the d.c. bus of the VSC transmission system;
d
I d.c. current of the d.c. bus of the VSC transmission system.
d
3.3 Power semiconductor terms
NOTE There are several types of switched valve devices which can be used in voltage sourced converters (VSC)
for HVDC and currently the IGBT is the major device used in such converters. The term IGBT is used throughout
this technical report to refer to the switched valve device. However, the technical report is equally applicable to
other types of devices with turn-off capability in most of the parts.

– 10 – TR 62543  IEC:2011(E)
3.3.1
switched valve devices
a controllable valve device which may be turned on and off by a control signal, for example

IGBT
3.3.2
insulated gate bipolar transistor

IGBT
a controllable switch with the capability to turn-on and turn-off a load current. An IGBT has

three terminals: a gate terminal (G) and two load terminals emitter (E) and collector (C).

By applying appropriate gate to emitter voltages, current in one direction can be controlled,
i.e. turned on and turned off.
3.3.3
free-wheeling diode
FWD
power semiconductor device with diode characteristic. A FWD has two terminals: an anode
(A) and a cathode (K). The current through FWDs is in opposite direction to the IGBT current.
FWDs are characterized by the capability to cope with high rates of decrease of current
caused by the switching behaviour of the IGBT.
3.3.4
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.4 VSC topologies
3.4.1
symmetrical monopole
a single VSC converter with symmetrical d.c. voltage output on the two terminals
3.4.2
asymmetrical monopole
a single VSC converter with asymmetrical d.c. voltage output on the two terminals, normally
with one terminal earthed
3.4.3
bipole
two or more VSC asymmetrical monopoles forming a bipolar d.c. circuit

3.4.4
two-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between two
discrete d.c. voltage levels
3.4.5
three-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
three discrete d.c. voltage levels
3.4.6
multi-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
more than three discrete d.c. voltage levels

TR 62543  IEC:2011(E) – 11 –
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve consists of a number of self-contained, single-

phase voltage sourced converters connected in series

3.4.8
VSC unit
three VSC phase units, together with VSC unit control equipment, essential protective and

switching devices, d.c. storage capacitors, valve reactor and auxiliaries, if any, used for
conversion
3.4.9
VSC phase unit
the equipment used to connect the two d.c. busbars to one a.c. terminal
NOTE In the simplest implementation, the VSC phase unit consists of two VSC valves. In some case, it consists
of two VSC valves and valve reactors. The VSC phase unit may also include control and protection equipment, and
other components.
3.4.10
VSC valve
complete controllable device assembly, which represents a functional unit as part of a VSC
phase unit and characterized by switching actions of the power electronic devices upon
control signals of the converter base electronics
NOTE Dependent on the converter topology, a valve can either have the function to act like a controllable switch
or to act like a controllable voltage source.
3.4.11
diode valve
a semiconductor valve containing diodes but no switched semiconductor devices, which might
be used in some VSC topologies
3.4.12
valve
refers to VSC valve or diode valve according to the context
3.4.13
VSC valve level
part of a VSC valve comprising a controllable switch and an associated diode, or controllable
switches and diodes connected in parallel, or controllable switches and diodes connected to a
half bridge or full bridge arrangement, together with their immediate auxiliaries, storage
capacitor, if any
NOTE In the context of modular multi-level converters, the term “submodule” is also used to refer to a VSC valve
level.
3.4.14
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.15
redundant levels
the maximum number of VSC valve levels or diode valve levels in a valve that may be short-
circuited externally or internally during service without affecting the safe operation of the
valve as demonstrated by type tests, and which if and when exceeded, would require
shutdown of the valve to replace the failed levels or acceptance of increased risk of failures

– 12 – TR 62543  IEC:2011(E)
3.4.16
valve protective blocking
means of protecting the valve or converter from excessive electrical stress by the emergency

turn-off of all IGBTs in one or more valves

3.4.17
submodule d.c. capacitor
a capacitor (if any) used as part of a certain VSC valve level, which is used as energy storage

d.c. source
3.4.18
valve reactor
a reactor (if any) which is connected in series to the VSC valve. One or more valve reactors
can be associated to one VSC valve and might be connected at different positions within the
valve. According to the definition, valve reactors are not part of the VSC valve. However, it is
also possible to integrate the valve reactors in the structural design of the VSC valve, e.g. into
each valve level.
NOTE At present valve reactors are used in converter topologies with valves acting like a controllable voltage
source only.
3.4.19
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.4.20
valve support
that part of the valve which mechanically supports and electrically insulates the active part of
the valve from earth
NOTE A part of a valve which is clearly identifiable in a discrete form to be a valve support may not exist in all
designs of valves.
3.4.21
multiple valve unit
MVU
mechanical arrangement of 2 or more valves or 1 or more VSC phase units sharing a common
valve support
NOTE A MVU might not exist in all topologies and physical arrangement of converters.
3.4.22
valve section
electrical assembly, composing a number of VSC or diode valve levels and other components,
which exhibits pro-rated electrical properties of a complete valve
3.4.23
valve base electronics
VBE
electronic unit, at earth potential, which is the interface between the converter control system
and the VSC valves
3.5 VSC transmission
3.5.1
VSC substation
part of a VSC transmission scheme, consisting of one or more VSC unit(s) installed in a single
location together with buildings, VSC d.c. capacitors, reactors, transformers, filters, control,
monitoring, protective, measuring and auxiliary equipment, as applicable

TR 62543  IEC:2011(E) – 13 –
3.5.2
interface transformer
transformer (if any) through which power is transmitted between the a.c. system connection

point and one or more VSC units

3.5.3
phase reactor
a reactor connected directly to the a.c. terminal of the VSC phase unit, and combined with

interface transformer leakage reactance (if any), in order to provide the commutating

reactance
3.5.4
VSC d.c. capacitor
capacitor bank (s) (if any) connected between two d.c. terminals of the VSC, used as energy
storage and / or filtering purposes
3.5.5
a.c. system side harmonic filter
a filter (if any) used to prevent harmonics generated by the VSC from penetrating into the a.c.
system. The filter can be located at the point of common coupling (outside the interface
transformer) or/ and on the valve side (inside the interface transformer)
3.5.6
a.c. side radio frequency interference filter (RFI filter)
filters (if any) used to reduce penetration of radio frequency interference (RFI) into the a.c.
system to an acceptable level
3.5.7
HF-blocking filter
filters (if any) used to reduce penetration of high frequency (HF) harmonics into the a.c.
system to an acceptable level
3.5.8
valve side harmonic filter
filters (if any) used to mitigate the HF stresses of the interface transformer
3.5.9
common mode blocking reactor
a reactor (if any) used to reduce common mode harmonic currents flowing into a d.c.
overhead line or cable of a bipolar long distance transmission scheme
3.5.10
d.c. harmonic filter
d.c. filters (if any) used to prevent harmonics generated by VSC valve from penetrating into
the d.c. system. The filter can consist of a tuned shunt branch, smoothing reactor or common
mode blocking reactor or combinations thereof.
3.5.11
d.c. reactor
a reactor (if any) connected in series to a d.c. overhead transmission line or cable used to
reduce harmonic currents flowing in the d.c. line or cable and to detune critical resonances
within the d.c. circuit. A d.c. reactor might also be used for protection purposes.
3.5.12
d.c. side radio frequency interference filter
filters (if any) used to reduce penetration of radio frequency (RF) into the d.c. system to
acceptable limits
– 14 – TR 62543  IEC:2011(E)
3.6 Operating states
NOTE This report only defines some operating states of the components of the VSC system, while the system
operating states are not included.

3.6.1
rectifier operation
operation mode of a VSC unit or a VSC substation when energy is transferred from the a.c.

side to the d.c. side
3.6.2
inverter operation
operation mode of a VSC unit or a VSC substation when energy is transferred from the d.c.
side to the a.c. side
3.6.3
STATCOM operation
mode of operation with reactive power exchange to the a.c. terminals and without energy
transfer on the d.c. line
3.6.4
forward valve direction
direction of current through a VSC valve, when current flows from the positive terminal to the
negative terminal
3.6.5
reverse valve direction
direction of current through a VSC valve, when current flows from the negative terminal to the
positive terminal
3.6.6
forward valve current
current which flows through a VSC valve in forward valve direction
3.6.7
reverse valve current
current which flows through a VSC valve in reverse valve direction
3.6.8
VSC blocking
operation preventing further conversion by a VSC unit by inhibiting valve control signal or
applying a signal to turn off IGBTs

3.6.9
VSC deblocking
operation permitting the start of conversion by a converter by removing blocking action
3.6.10
conducting state
the condition in which load current flows through an IGBT-diode pair. In IGBT-diode pair, both
positive and negative conducting states may exist.
3.6.11
positive conducting state
the condition of an IGBT-diode pair in which load current flows through the IGBT from
collector to emitter
TR 62543  IEC:2011(E) – 15 –
3.6.12
negative conducting state
the condition of an IGBT-diode pair in which load current flows through the free-wheeling

diode from anode to cathode
3.6.13
blocked state
the condition of an IGBT-diode pair in which load current does not flow and a voltage is

applied to the IGBT-diode pair such that a positive voltage exists on the collector of the IGBT

with respect to the emitter
3.6.14
reverse recovery state
the condition in which the FWD carries reverse current during commutation at the specified
conditions, starting at the zero-crossing of the current and ending when the reverse current
has decayed to the reverse off-state current after the tail-current phase
3.6.15
modulation index of PWM converters
M
modulation index M is the ratio of the modulating wave amplitude to the carrier amplitude
V Peak _ of _(V )
control A0 1
(1)
M = =
V (V / 2)
triangle dc
where
(V ) is the fundamental frequency component of V ,
A0 1 A0
V is the output voltage of one VSC phase unit at its a.c. terminal.
A0
NOTE In addition, there are various definitions of modulation index for VSC converters available. All of these
modulation indices represent secondary quantities which are derived from physical properties and operating
principles of VSC converters. It is to be noted that for a specific application any modulation index and its usage
should be defined clearly.
3.7 Type tests
Those tests which are carried out to verify that the components of VSC transmission system
design will meet the requirements specified. In this report, type tests are classified under two
major categories: dielectric tests and operational tests.
3.7.1
dielectric tests
those tests which are carried out to verify the high voltage withstanding capability of the
components of VSC transmission system
3.7.2
operational tests
those tests which are carried out to verify the turn-on (if applicable), turn-off (if applicable),
and current related capabilities of the components o
...

IEC/TR 62543 ®
Edition 1.0 2011-03
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
IEC/TR 62543:2011(E)
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IEC/TR 62543 ®
Edition 1.0 2011-03
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.200; 29.240.99 ISBN 978-2-88912-424-4

– 2 – TR 62543  IEC:2011(E)
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
3.1 General . 8
3.2 Letter symbols . 9
3.3 Power semiconductor terms . 9
3.4 VSC topologies . 10
submodule d.c. capacitor . 12
3.5 VSC transmission . 12
3.6 Operating states . 14
3.7 Type tests . 15
3.8 Production tests . 15
3.9 Sample tests . 15
3.10 Insulation co-ordination terms . 16
3.11 Power losses . 16
4 VSC transmission overview . 17
4.1 Basic operating principles of VSC transmission . 17
4.1.1 The voltage sourced converter as a black box . 17
4.1.2 The principles of active and reactive power control . 18
4.1.3 Operating principles of a VSC transmission scheme . 19
4.1.4 Applications of VSC transmission . 20
4.2 Design life . 20
4.3 VSC transmission configurations . 20
4.3.1 General . 20
4.3.2 D.C. circuit configurations . 21
4.3.3 Monopole configuration . 21
4.3.4 Bipolar configuration . 22
4.3.5 Parallel connection of two converters . 22
4.3.6 Series connection of two converters . 23
4.3.7 Parallel and series connection of more than two converters . 23
4.4 Semiconductors for VSC transmission . 23
5 VSC transmission converter topologies . 25
5.1 General . 25
5.2 Converter topologies with VSC valves of “switch” type . 25
5.2.1 General . 25
5.2.2 Operating principle . 26
5.2.3 Topologies . 26
5.3 Converter topologies with VSC valves of the “controllable voltage source”
type . 29
5.3.1 General . 29
5.3.2 MMC topology with VSC levels in half-bridge topology . 30
5.3.3 MMC topology with VSC levels in full-bridge topology . 31
5.4 VSC valve design considerations . 32
5.4.1 Reliability and failure mode . 32
5.4.2 Current rating . 33

TR 62543  IEC:2011(E) – 3 –
5.4.3 Transient current and voltage requirements . 33
5.4.4 Diode requirements . 33
5.4.5 Additional design details . 34
5.5 Other converter topologies . 34
5.6 Other equipment for VSC transmission schemes . 35
5.6.1 General . 35
5.6.2 Power components of a VSC transmission scheme . 35
5.6.3 VSC substation circuit breaker . 35
5.6.4 A.C. system side harmonic filters . 35
5.6.5 Radio frequency interference filters . 36
5.6.6 Interface transformers and phase reactors . 36
5.6.7 Valve reactor . 37
5.6.8 D.C. capacitors . 37
5.6.9 D.C. reactor . 39
5.6.10 Common mode blocking reactor . 39
5.6.11 D.C. filter . 39
6 Overview of VSC controls . 39
6.1 General . 39
6.2 Operational modes and operational options . 40
6.3 Power transfer . 41
6.3.1 General . 41
6.3.2 Telecommunication between converter stations . 42
6.4 Reactive power and a.c. voltage control . 42
6.4.1 A.C. voltage control . 42
6.4.2 Reactive power control . 42
6.5 Black start capability . 43
6.6 Supply from a wind farm . 43
7 Steady state operation . 44
7.1 Steady state capability . 44
7.2 Converter power losses . 45
8 Dynamic performance . 45
8.1 A.C. system disturbances . 45
8.2 D.C. system disturbances . 46
8.2.1 D.C. cable fault . 46
8.2.2 D.C. overhead line fault . 46
8.3 Internal faults . 46
9 HVDC performance requirements . 47
9.1 Harmonic performance . 47
9.2 Wave distortion . 48
9.3 Fundamental and harmonics . 48
9.3.1 Three-phase 2-level VSC . 48
9.3.2 Selective harmonic elimination modulation . 50
9.3.3 Multi-pulse and multi-level converters . 51
9.4 Harmonic voltages on power systems due to VSC operation . 51
9.5 Design considerations for harmonic filters (a.c. side) . 52
9.6 D.C. side filtering . 52
10 Environmental impact . 52
10.1 General . 52

– 4 – TR 62543  IEC:2011(E)
10.2 Audible noise . 52
10.3 Electric and magnetic fields (EMF) . 53
10.4 Electromagnetic compatibility (EMC) . 53
11 Testing and commissioning . 54
11.1 General . 54
11.2 Factory tests . 54
11.2.1 Component tests . 54
11.2.2 Control system tests . 54
11.3 Commissioning tests / System tests . 55
11.3.1 General . 55
11.3.2 Precommissioning tests . 55
11.3.3 Subsystem tests . 55
11.3.4 System tests . 56
Annex A (informative) Functional specification requirements for VSC transmission
systems . 60
Annex B (informative) Determination of VSC valve power losses . 68
Bibliography . 77

Figure 1 – Major components that may be found in a VSC substation . 9
Figure 2 – Diagram of a generic voltage source converter (a.c. filters not shown) . 17
Figure 3 – The principle of active power control . 18
Figure 4 – The principle of reactive power control . 19
Figure 5 – A point-to-point VSC transmission scheme . 19
Figure 6 – VSC transmission with a symmetrical monopole . 21
Figure 7 – VSC transmission with an asymmetrical monopole with metallic return . 22
Figure 8 – VSC transmission with an asymmetrical monopole with earth return . 22
Figure 9 – VSC transmission in bipolar configuration . 22
Figure 10 – Parallel connection of two converter units . 23
Figure 11 – Symbol of a controllable switch and associated free-wheeling diode . 24
Figure 12 – Symbol of an IGBT . 24
Figure 13 – Diagram of a three-phase 2-level converter and associated a.c. waveform
for one phase. 26
Figure 14 – Single-phase a.c. output for 2-level converter with PWM switching at 21
times fundamental frequency . 27
Figure 15 – Diagram of a three-phase 3-level NPC converter and associated a.c.
waveform for one phase . 28
Figure 16 – Single-phase a.c. output for 3-level NPC converter with PWM switching at
21 times fundamental frequency . 29
Figure 17 – Electrical equivalent for a converter with VSC valves acting like a
controllable voltage source . 30
Figure 18 – VSC valve level arrangement and equivalent circuit in MMC topology in
half-bridge topology . 30
Figure 19 – Converter block arrangement with MMC topology in half-bridge topology . 31
Figure 20 – VSC valve level arrangement and equivalent circuit in MMC topology with
full-bridge topology . 32
Figure 21 – Typical SSOA for the IGBT . 33
Figure 22 – A 2-level VSC bridge with the IGBTs turned off . 33

TR 62543  IEC:2011(E) – 5 –
Figure 23 – Representing a VSC unit as an a.c. voltage of magnitude U and phase
angle δ behind reactance . 40
Figure 24 – Concept of vector control . 41
Figure 25 – VSC power controller . 41
Figure 26 – A.C. voltage controller . 42
Figure 27 – A typical simplified PQ diagram . 44
Figure 28 – Protection concept of a VSC substation. 47
Figure 29 – Waveforms for three-phase 2-level VSC . 49
Figure 30 – Voltage harmonics spectra of a 2-level VSC with carrier frequency at 21st
harmonic . 50
Figure 31 – Phase output voltage for selective harmonic elimination modulation
(SHEM) . 50
Figure 32 – Equivalent circuit at the PCC of the VSC . 51
Figure B.1 – On state voltage of an IGBT or free-wheeling diode . 69
Figure B.2 – Piecewise-linear representation of IGBT or FWD on-state voltage . 70
Figure B.3 – IGBT switching losses as a function of collector current . 73
Figure B.4 – Free-wheeling diode recovery loss as a function of current . 74

– 6 – TR 62543  IEC:2011(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION
USING VOLTAGE SOURCED CONVERTERS (VSC)

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC/TR 62543, which is a technical report, 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 present technical report cancels and replaces IEC/PAS 62543:2008 (Ed.1) which was
published by IEC and CIGRÉ jointly, and combined with engineering experience.
The present IEC/TR 62543 bears the edition number 1.

TR 62543  IEC:2011(E) – 7 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
22F/230/DTR 22F/239A/RVC
Full information on the voting for the approval of this technical report 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.
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
understanding of its contents. Users should therefore print this document using a
colour printer.
A bilingual version of this publication may be issued at a later date.

– 8 – TR 62543  IEC:2011(E)
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION
USING VOLTAGE SOURCED CONVERTERS (VSC)

1 Scope
This technical report gives general guidance on the subject of voltage-sourced converters
used for transmission of power by high voltage direct current (HVDC). It describes converters
that are not only voltage-sourced (containing a capacitive energy storage medium and where
the polarity of d.c. voltage remains fixed) but also self-commutated, using semiconductor
devices which can both be turned on and turned off by control action. The scope includes
2-level and 3-level converters with pulse-width modulation (PWM), along with multi-level
converters, but excludes 2-level and 3-level converters operated without PWM, in square-
wave output mode.
HVDC power transmission using voltage sourced converters is known as “VSC transmission”.
The various types of circuit that can be used for VSC transmission are described in the report,
along with their principal operational characteristics and typical applications. The overall aim
is to provide a guide for purchasers to assist with the task of specifying a VSC transmission
scheme.
Line-commutated and current-sourced converters are specifically excluded from this report.
2 Normative references
The following referenced documents are indispensable for the application 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 60633, Terminology for high-voltage direct-current (HVDC) transmission
IEC 61975, High-voltage direct current (HVDC) installations – System tests
3 Terms and definitions
For the purpose of this document, the following definitions apply.
3.1 General
NOTE This report uses the terminology established by IEC 60633 and IEC 61803 for line-commutated HVDC.
Only terms which are specific to HVDC transmission using voltage sourced converters are defined in this clause.
Those terms that are either identical to or obvious extensions of IEC 60633 or IEC 61803 terminology have not
been defined.
To support the explanations, Figure 1 presents the basic diagram of a VSC system. Dependent on the converter
topology and the requirements in the project, some components can be omitted or can differ.

TR 62543  IEC:2011(E) – 9 –
~
DC line of
j
the second pole
=
k
a b c d e f g h i l m n o
IEC  567/11
Figure 1 – Major components that may be found in a VSC substation
b
a circuit breaker i VSC d.c. capacitor
b line side harmonic filter j d.c. harmonic filter
c
c line side high frequency filter k neutral point grounding branch
d
d interface transformer l d.c. reactor
d
e converter side harmonic filter m common mode blocking reactor
a d
f + g converter side high frequency filter n d.c. side high frequency filter
a b
g phase reactor o d.c. cable or overhead transmission line

h VSC unit
a
In some designs of VSC, the phase reactor may fulfil part of the function of the converter-side high frequency
filter. In addition, in some designs of VSC, part of or all of the phase reactor may be built into the three “Phase
units” of the VSC unit, as “Valve reactors”.
b
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 the d.c. submodule capacitors.
c
The location of the neutral point grounding branch may be different depending on the design of the VSC unit.
d
Not normally required for back-to-back systems.
3.2 Letter symbols
line-to-line a.c. voltage of the converter unit(s), r.m.s. value, including
U
conv
harmonics;
alternating current of the converter unit(s), r.m.s. value, including
I
conv
harmonics;
line-to-line a.c. voltage of the a.c. system, r.m.s. value, including
U
L
harmonics;
I alternating current of the a.c. system, r.m.s. value, including harmonics;
L
U d.c. line-to-line voltage of the d.c. bus of the VSC transmission system;
d
I d.c. current of the d.c. bus of the VSC transmission system.
d
3.3 Power semiconductor terms
NOTE There are several types of switched valve devices which can be used in voltage sourced converters (VSC)
for HVDC and currently the IGBT is the major device used in such converters. The term IGBT is used throughout
this technical report to refer to the switched valve device. However, the technical report is equally applicable to
other types of devices with turn-off capability in most of the parts.

– 10 – TR 62543  IEC:2011(E)
3.3.1
switched valve devices
a controllable valve device which may be turned on and off by a control signal, for example
IGBT
3.3.2
insulated gate bipolar transistor
IGBT
a controllable switch with the capability to turn-on and turn-off a load current. An IGBT has
three terminals: a gate terminal (G) and two load terminals emitter (E) and collector (C).
By applying appropriate gate to emitter voltages, current in one direction can be controlled,
i.e. turned on and turned off.
3.3.3
free-wheeling diode
FWD
power semiconductor device with diode characteristic. A FWD has two terminals: an anode
(A) and a cathode (K). The current through FWDs is in opposite direction to the IGBT current.
FWDs are characterized by the capability to cope with high rates of decrease of current
caused by the switching behaviour of the IGBT.
3.3.4
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.4 VSC topologies
3.4.1
symmetrical monopole
a single VSC converter with symmetrical d.c. voltage output on the two terminals
3.4.2
asymmetrical monopole
a single VSC converter with asymmetrical d.c. voltage output on the two terminals, normally
with one terminal earthed
3.4.3
bipole
two or more VSC asymmetrical monopoles forming a bipolar d.c. circuit
3.4.4
two-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between two
discrete d.c. voltage levels
3.4.5
three-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
three discrete d.c. voltage levels
3.4.6
multi-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
more than three discrete d.c. voltage levels

TR 62543  IEC:2011(E) – 11 –
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve consists of a number of self-contained, single-
phase voltage sourced converters connected in series
3.4.8
VSC unit
three VSC phase units, together with VSC unit control equipment, essential protective and
switching devices, d.c. storage capacitors, valve reactor and auxiliaries, if any, used for
conversion
3.4.9
VSC phase unit
the equipment used to connect the two d.c. busbars to one a.c. terminal
NOTE In the simplest implementation, the VSC phase unit consists of two VSC valves. In some case, it consists
of two VSC valves and valve reactors. The VSC phase unit may also include control and protection equipment, and
other components.
3.4.10
VSC valve
complete controllable device assembly, which represents a functional unit as part of a VSC
phase unit and characterized by switching actions of the power electronic devices upon
control signals of the converter base electronics
NOTE Dependent on the converter topology, a valve can either have the function to act like a controllable switch
or to act like a controllable voltage source.
3.4.11
diode valve
a semiconductor valve containing diodes but no switched semiconductor devices, which might
be used in some VSC topologies
3.4.12
valve
refers to VSC valve or diode valve according to the context
3.4.13
VSC valve level
part of a VSC valve comprising a controllable switch and an associated diode, or controllable
switches and diodes connected in parallel, or controllable switches and diodes connected to a
half bridge or full bridge arrangement, together with their immediate auxiliaries, storage
capacitor, if any
NOTE In the context of modular multi-level converters, the term “submodule” is also used to refer to a VSC valve
level.
3.4.14
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.15
redundant levels
the maximum number of VSC valve levels or diode valve levels in a valve that may be short-
circuited externally or internally during service without affecting the safe operation of the
valve as demonstrated by type tests, and which if and when exceeded, would require
shutdown of the valve to replace the failed levels or acceptance of increased risk of failures

– 12 – TR 62543  IEC:2011(E)
3.4.16
valve protective blocking
means of protecting the valve or converter from excessive electrical stress by the emergency
turn-off of all IGBTs in one or more valves
3.4.17
submodule d.c. capacitor
a capacitor (if any) used as part of a certain VSC valve level, which is used as energy storage
d.c. source
3.4.18
valve reactor
a reactor (if any) which is connected in series to the VSC valve. One or more valve reactors
can be associated to one VSC valve and might be connected at different positions within the
valve. According to the definition, valve reactors are not part of the VSC valve. However, it is
also possible to integrate the valve reactors in the structural design of the VSC valve, e.g. into
each valve level.
NOTE At present valve reactors are used in converter topologies with valves acting like a controllable voltage
source only.
3.4.19
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.4.20
valve support
that part of the valve which mechanically supports and electrically insulates the active part of
the valve from earth
NOTE A part of a valve which is clearly identifiable in a discrete form to be a valve support may not exist in all
designs of valves.
3.4.21
multiple valve unit
MVU
mechanical arrangement of 2 or more valves or 1 or more VSC phase units sharing a common
valve support
NOTE A MVU might not exist in all topologies and physical arrangement of converters.
3.4.22
valve section
electrical assembly, composing a number of VSC or diode valve levels and other components,
which exhibits pro-rated electrical properties of a complete valve
3.4.23
valve base electronics
VBE
electronic unit, at earth potential, which is the interface between the converter control system
and the VSC valves
3.5 VSC transmission
3.5.1
VSC substation
part of a VSC transmission scheme, consisting of one or more VSC unit(s) installed in a single
location together with buildings, VSC d.c. capacitors, reactors, transformers, filters, control,
monitoring, protective, measuring and auxiliary equipment, as applicable

TR 62543  IEC:2011(E) – 13 –
3.5.2
interface transformer
transformer (if any) through which power is transmitted between the a.c. system connection
point and one or more VSC units
3.5.3
phase reactor
a reactor connected directly to the a.c. terminal of the VSC phase unit, and combined with
interface transformer leakage reactance (if any), in order to provide the commutating
reactance
3.5.4
VSC d.c. capacitor
capacitor bank (s) (if any) connected between two d.c. terminals of the VSC, used as energy
storage and / or filtering purposes
3.5.5
a.c. system side harmonic filter
a filter (if any) used to prevent harmonics generated by the VSC from penetrating into the a.c.
system. The filter can be located at the point of common coupling (outside the interface
transformer) or/ and on the valve side (inside the interface transformer)
3.5.6
a.c. side radio frequency interference filter (RFI filter)
filters (if any) used to reduce penetration of radio frequency interference (RFI) into the a.c.
system to an acceptable level
3.5.7
HF-blocking filter
filters (if any) used to reduce penetration of high frequency (HF) harmonics into the a.c.
system to an acceptable level
3.5.8
valve side harmonic filter
filters (if any) used to mitigate the HF stresses of the interface transformer
3.5.9
common mode blocking reactor
a reactor (if any) used to reduce common mode harmonic currents flowing into a d.c.
overhead line or cable of a bipolar long distance transmission scheme
3.5.10
d.c. harmonic filter
d.c. filters (if any) used to prevent harmonics generated by VSC valve from penetrating into
the d.c. system. The filter can consist of a tuned shunt branch, smoothing reactor or common
mode blocking reactor or combinations thereof.
3.5.11
d.c. reactor
a reactor (if any) connected in series to a d.c. overhead transmission line or cable used to
reduce harmonic currents flowing in the d.c. line or cable and to detune critical resonances
within the d.c. circuit. A d.c. reactor might also be used for protection purposes.
3.5.12
d.c. side radio frequency interference filter
filters (if any) used to reduce penetration of radio frequency (RF) into the d.c. system to
acceptable limits
– 14 – TR 62543  IEC:2011(E)
3.6 Operating states
NOTE This report only defines some operating states of the components of the VSC system, while the system
operating states are not included.
3.6.1
rectifier operation
operation mode of a VSC unit or a VSC substation when energy is transferred from the a.c.
side to the d.c. side
3.6.2
inverter operation
operation mode of a VSC unit or a VSC substation when energy is transferred from the d.c.
side to the a.c. side
3.6.3
STATCOM operation
mode of operation with reactive power exchange to the a.c. terminals and without energy
transfer on the d.c. line
3.6.4
forward valve direction
direction of current through a VSC valve, when current flows from the positive terminal to the
negative terminal
3.6.5
reverse valve direction
direction of current through a VSC valve, when current flows from the negative terminal to the
positive terminal
3.6.6
forward valve current
current which flows through a VSC valve in forward valve direction
3.6.7
reverse valve current
current which flows through a VSC valve in reverse valve direction
3.6.8
VSC blocking
operation preventing further conversion by a VSC unit by inhibiting valve control signal or
applying a signal to turn off IGBTs
3.6.9
VSC deblocking
operation permitting the start of conversion by a converter by removing blocking action
3.6.10
conducting state
the condition in which load current flows through an IGBT-diode pair. In IGBT-diode pair, both
positive and negative conducting states may exist.
3.6.11
positive conducting state
the condition of an IGBT-diode pair in which load current flows through the IGBT from
collector to emitter
TR 62543  IEC:2011(E) – 15 –
3.6.12
negative conducting state
the condition of an IGBT-diode pair in which load current flows through the free-wheeling
diode from anode to cathode
3.6.13
blocked state
the condition of an IGBT-diode pair in which load current does not flow and a voltage is
applied to the IGBT-diode pair such that a positive voltage exists on the collector of the IGBT
with respect to the emitter
3.6.14
reverse recovery state
the condition in which the FWD carries reverse current during commutation at the specified
conditions, starting at the zero-crossing of the current and ending when the reverse current
has decayed to the reverse off-state current after the tail-current phase
3.6.15
modulation index of PWM converters
M
modulation index M is the ratio of the modulating wave amplitude to the carrier amplitude
V Peak _ of _(V )
control A0 1
(1)
M = =
V (V / 2)
triangle dc
where
(V ) is the fundamental frequency component of V ,
A0 1 A0
V is the output voltage of one VSC phase unit at its a.c. terminal.
A0
NOTE In addition, there are various definitions of modulation index for VSC converters available. All of these
modulation indices represent secondary quantities which are derived from physical properties and operating
principles of VSC converters. It is to be noted that for a specific application any modulation index and its usage
should be defined clearly.
3.7 Type tests
Those tests which are carried out to verify that the components of VSC transmission system
design will meet the requirements specified. In this report, type tests are classified under two
major categories: dielectric tests and operational tests.
3.7.1
dielectric tests
those tests which are carried out to verify the high voltage withstanding capability of the
components of VSC transmission system
3.7.2
operational tests
those tests which are carried out to verify the turn-on (if applicable), turn-off (if applicable),
and current related capabilities of the components of VSC transmission system
3.8 Production tests
Those tests which are carried out to verify proper manufacture, so that the properties of the
certain component of VSC transmission system correspond to those specified
3.9 Sample tests
Those production tests which are carried out on a small number of certain VSC transmission
components, e.g. valve sections or special components taken at random from a batch
...

IEC/TR 62543 ®
Edition 1.1 2013-07
CONSOLIDATED
VERSION
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
IEC/TR 62543:2011+A1:2013
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IEC/TR 62543 ®
Edition 1.1 2013-07
CONSOLIDATED
VERSION
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced

converters (VSC)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200; 29.240.99 ISBN 978-2-8322-1031-4

IEC/TR 62543 ®
Edition 1.1 2013-07
REDLINE VERSION
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
IEC/TR 62543:2011+A1:2013
– 2 – TR 62543  IEC:2011+A1:2013(E)

CONTENTS
FOREWORD . 6

1 Scope . 8

2 Normative references . 8

3 Terms and definitions . 8

3.1 General . 8

3.2 Letter symbols . 9

3.3 Power semiconductor terms . 9

3.4 VSC topologies . 10
3.5 VSC transmission . 13
3.6 Operating states . 14
3.7 Type tests . 16
3.8 Production tests . 17
3.9 Sample tests . 17
3.10 Insulation co-ordination terms . 17
3.11 Power losses . 17
4 VSC transmission overview . 18
4.1 Basic operating principles of VSC transmission . 18
4.1.1 The voltage sourced converter as a black box . 18
4.1.2 The principles of active and reactive power control . 19
4.1.3 Operating principles of a VSC transmission scheme . 21
4.1.4 Applications of VSC transmission . 21
4.2 Design life . 22
4.3 VSC transmission configurations . 22
4.3.1 General . 22
4.3.2 D.C. circuit configurations . 22
4.3.3 Monopole configuration . 22
4.3.4 Bipolar configuration . 23
4.3.5 Parallel connection of two converters . 24
4.3.6 Series connection of two converters . 24
4.3.7 Parallel and series connection of more than two converters . 25
4.4 Semiconductors for VSC transmission . 25
5 VSC transmission converter topologies . 26
5.1 General . 26

5.2 Converter topologies with VSC valves of “switch” type . 27
5.2.1 General . 27
5.2.2 Operating principle . 27
5.2.3 Topologies . 28
5.3 Converter topologies with VSC valves of the “controllable voltage source”
type . 31
5.3.1 General . 31
5.3.2 MMC topology with VSC levels in half-bridge topology . 33
5.3.3 MMC topology with VSC levels in full-bridge topology . 35
5.3.4 CTL topology with VSC cells in half-bridge topology . 33
5.3.5 CTL topology with VSC cells in full-bridge topology . 33
5.4 VSC valve design considerations . 37
5.4.1 Reliability and failure mode . 37
5.4.2 Current rating . 37

TR 62543  IEC:2011+A1:2013(E) – 3 –

5.4.3 Transient current and voltage requirements . 37

5.4.4 Diode requirements . 38

5.4.5 Additional design details . 38

5.5 Other converter topologies . 39

5.6 Other equipment for VSC transmission schemes . 39

5.6.1 General . 39

5.6.2 Power components of a VSC transmission scheme . 39

5.6.3 VSC substation circuit breaker . 40

5.6.4 A.C. system side harmonic filters . 40

5.6.5 Radio frequency interference filters . 40

5.6.6 Interface transformers and phase reactors . 40
5.6.7 Valve reactor . 41
5.6.8 D.C. capacitors . 41
5.6.9 D.C. reactor . 43
5.6.10 Common mode blocking reactor . 43
5.6.11 D.C. filter . 44
5.6.12 Dynamic braking system. . 44
6 Overview of VSC controls . 44
6.1 General . 44
6.2 Operational modes and operational options . 45
6.3 Power transfer . 46
6.3.1 General . 46
6.3.2 Telecommunication between converter stations . 47
6.4 Reactive power and a.c. voltage control . 47
6.4.1 A.C. voltage control . 47
6.4.2 Reactive power control . 47
6.5 Black start capability . 48
6.6 Supply from a wind farm . 48
7 Steady state operation . 48
7.1 Steady state capability . 48
7.2 Converter power losses . 50
8 Dynamic performance . 50
8.1 A.C. system disturbances . 50
8.2 D.C. system disturbances . 51
8.2.1 D.C. cable fault . 51

8.2.2 D.C. overhead line fault . 51
8.3 Internal faults . 51
9 HVDC performance requirements . 52
9.1 Harmonic performance . 52
9.2 Wave distortion . 53
9.3 Fundamental and harmonics . 53
9.3.1 Three-phase 2-level VSC . 53
9.3.2 Selective harmonic elimination modulation . 55
9.3.3 Multi-pulse and multi-level converters . 56
9.4 Harmonic voltages on power systems due to VSC operation . 56
9.5 Design considerations for harmonic filters (a.c. side) . 57
9.6 D.C. side filtering . 57

– 4 – TR 62543  IEC:2011+A1:2013(E)

10 Environmental impact . 57

10.1 General . 57

10.2 Audible noise . 57

10.3 Electric and magnetic fields (EMF) . 58

10.4 Electromagnetic compatibility (EMC) . 58

11 Testing and commissioning . 59

11.1 General . 59

11.2 Factory tests . 59

11.2.1 Component tests . 59

11.2.2 Control system tests . 59
11.3 Commissioning tests / System tests . 60
11.3.1 General . 60
11.3.2 Precommissioning tests . 60
11.3.3 Subsystem tests . 60
11.3.4 System tests . 61
Annex A (informative) Functional specification requirements for VSC transmission
systems . 65
Annex B (informative) Determination of VSC valve power losses . 73
Bibliography . 82

Figure 1 – Major components that may be found in a VSC substation . 9
Figure 2 – Diagram of a generic voltage source converter (a.c. filters not shown) . 18
Figure 3 – The principle of active power control . 19
Figure 4 – The principle of reactive power control . 20
Figure 5 – A point-to-point VSC transmission scheme . 21
Figure 6 – VSC transmission with a symmetrical monopole . 23
Figure 7 – VSC transmission with an asymmetrical monopole with metallic return . 23
Figure 8 – VSC transmission with an asymmetrical monopole with earth return . 23
Figure 9 – VSC transmission in bipolar configuration . 24
Figure 10 – Parallel connection of two converter units . 24
Figure 11 – Symbol of a controllable switch turn-off semi-conductor device and
associated free-wheeling diode . 25
Figure 12 – Symbol of an IGBT and associated free-wheeling diode . 26

Figure 13 – Diagram of a three-phase 2-level converter and associated a.c. waveform
for one phase. 28
Figure 14 – Single-phase a.c. output for 2-level converter with PWM switching at 21
times fundamental frequency . 29
Figure 15 – Diagram of a three-phase 3-level NPC converter and associated a.c.
waveform for one phase . 30
Figure 16 – Single-phase a.c. output for 3-level NPC converter with PWM switching at
21 times fundamental frequency . 31
Figure 17 – Electrical equivalent for a converter with VSC valves acting like a
controllable voltage source . 32
Figure 18 – VSC valve level arrangement and equivalent circuit in MMC topology in
half-bridge topology . 33
Figure 19 – Converter block arrangement with MMC topology in half-bridge topology . 35

TR 62543  IEC:2011+A1:2013(E) – 5 –

Figure 20 – VSC valve level arrangement and equivalent circuit in MMC topology with

full-bridge topology . 36

Figure 21 – Typical SSOA for the IGBT . 37

Figure 22 – A 2-level VSC bridge with the IGBTs turned off . 38

Figure 23 – Representing a VSC unit as an a.c. voltage of magnitude U and phase

angle δ behind reactance . 45

Figure 24 – Concept of vector control . 46

Figure 25 – VSC power controller . 46

Figure 26 – A.C. voltage controller . 47

Figure 27 – A typical simplified PQ diagram . 49
Figure 28 – Protection concept of a VSC substation. 52
Figure 29 – Waveforms for three-phase 2-level VSC . 54
Figure 30 – Voltage harmonics spectra of a 2-level VSC with carrier frequency at 21st
harmonic . 55
Figure 31 – Phase output voltage for selective harmonic elimination modulation
(SHEM) . 55
Figure 32 – Equivalent circuit at the PCC of the VSC . 56
Figure B.1 – On state voltage of an IGBT or free-wheeling diode . 74
Figure B.2 – Piecewise-linear representation of IGBT or FWD on-state voltage . 75
Figure B.3 – IGBT switching losses as a function of collector current . 78
Figure B.4 – Free-wheeling diode recovery loss as a function of current . 79

– 6 – TR 62543  IEC:2011+A1:2013(E)

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

FOREWORD
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This Consolidated version of IEC/TR 62543 bears the edition number 1.1. It consists of

the first edition (2011) [documents 22F/230/DTR and 22F/239A/RVC] and its amendment
1 (2013) [documents 22F/300A/DTR and 22F/307/RVC]. The technical content is identical
to the base edition and its amendment.
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions and deletions are displayed in red, with
deletions being struck through. A separate Final version with all changes accepted is
available in this publication.
This publication has been prepared for user convenience.

TR 62543  IEC:2011+A1:2013(E) – 7 –

The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".
IEC/TR 62543, which is a technical report, has been prepared by subcommittee 22F: Power
electronics for electrical transmission and distribution systems, of IEC technical committee 22:

Power electronic systems and equipment.

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

The committee has decided that the contents of the base publication and its amendment 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.
A bilingual version of this publication may be issued at a later date.
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 understanding
of its contents. Users should therefore print this publication using a colour printer.

– 8 – TR 62543  IEC:2011+A1:2013(E)

HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

1 Scope
This technical report gives general guidance on the subject of voltage-sourced converters
used for transmission of power by high voltage direct current (HVDC). It describes converters
that are not only voltage-sourced (containing a capacitive energy storage medium and where

the polarity of d.c. voltage remains fixed) but also self-commutated, using semiconductor
devices which can both be turned on and turned off by control action. The scope includes
2-level and 3-level converters with pulse-width modulation (PWM), along with multi-level
converters, modular multi-level converters and cascaded two-level converters, but excludes 2-
level and 3-level converters operated without PWM, in square-wave output mode.
HVDC power transmission using voltage sourced converters is known as “VSC transmission”.
The various types of circuit that can be used for VSC transmission are described in the report,
along with their principal operational characteristics and typical applications. The overall aim
is to provide a guide for purchasers to assist with the task of specifying a VSC transmission
scheme.
Line-commutated and current-sourced converters are specifically excluded from this report.
2 Normative references
The following referenced documents are indispensable for the application 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 60633, Terminology for high-voltage direct-current (HVDC) transmission
IEC 61975, High-voltage direct current (HVDC) installations – System tests
3 Terms and definitions
For the purpose of this document, the following definitions apply.

3.1 General
NOTE This report uses the terminology established by IEC 60633 and IEC 61803 for line-commutated HVDC.
Only terms which are specific to HVDC transmission using voltage sourced converters are defined in this clause.
Those terms that are either identical to or obvious extensions of IEC 60633 or IEC 61803 terminology have not
been defined.
To support the explanations, Figure 1 presents the basic diagram of a VSC system. Dependent on the converter
topology and the requirements in the project, some components can be omitted or can differ.

TR 62543  IEC:2011+A1:2013(E) – 9 –

~
DC line of
j
the second pole
=
k
a b c d e f g h i l m n o
IEC  567/11
Figure 1 – Major components that may be found in a VSC substation
b
a circuit breaker i VSC d.c. capacitor
b line side harmonic filter j d.c. harmonic filter
c
c line side high frequency filter k neutral point grounding branch
d
d interface transformer l d.c. reactor
d
e converter side harmonic filter m common mode blocking reactor
a d
f + g converter side high frequency filter n d.c. side high frequency filter
a b
g phase reactor o d.c. cable or overhead transmission line

h VSC unit
a
In some designs of VSC, the phase reactor may fulfil part of the function of the converter-side high frequency
filter. In addition, in some designs of VSC, part of or all of the phase reactor may be built into the three “Phase
units” of the VSC unit, as “Valve reactors”.
b
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 the d.c. cell or submodule capacitors.
c
The location of the neutral point grounding branch may be different depending on the design of the VSC unit.
d
Not normally required for back-to-back systems.
3.2 Letter symbols
line-to-line a.c. voltage of the converter unit(s), r.m.s. value, including
U
conv
harmonics;
alternating current of the converter unit(s), r.m.s. value, including
I
conv
harmonics;
line-to-line a.c. voltage of the a.c. system, r.m.s. value, including
U
L
harmonics;
I alternating current of the a.c. system, r.m.s. value, including harmonics;
L
U d.c. line-to-line voltage of the d.c. bus of the VSC transmission system;
d
I d.c. current of the d.c. bus of the VSC transmission system.
d
3.3 Power semiconductor terms
NOTE There are several types of switched valve devices which can be used in voltage sourced converters (VSC)
for HVDC and currently the IGBT is the major device used in such converters. The term IGBT is used throughout
this technical report to refer to the switched valve device. However, the technical report is equally applicable to
other types of devices with turn-off capability in most of the parts.

– 10 – TR 62543  IEC:2011+A1:2013(E)

3.3.1
turn-off semiconductor switched valve devices

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

for example IGBT
NOTE There are several types of turn-off semiconductor devices which can be used in voltage sourced converters
(VSC) for HVDC and currently the IGBT is the major device used in such converters. The term IGBT is used
throughout this technical report to refer to the turn-off semiconductor device. However, the technical report is

equally applicable to other types of devices with turn-off capability in most of the parts.

3.3.2
insulated gate bipolar transistor
IGBT
a controllable switch with the capability to turn-on and turn-off a load current. An IGBT has
turn-off semiconductor device with three terminals: a gate terminal (G) and two load terminals
emitter (E) and collector (C).
NOTE By applying appropriate gate to emitter voltages, current in one direction can be controlled, i.e. turned on
and turned off.
3.3.3
free-wheeling diode
FWD
power semiconductor device with diode characteristic.
NOTE 1 A FWD has two terminals: an anode (A) and a cathode (K).
NOTE 2 The current through FWDs is in opposite direction to the IGBT current.
NOTE 3 FWDs are characterized by the capability to cope with high rates of decrease of current caused by the
switching behaviour of the IGBT.
3.3.4
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.4 VSC topologies
3.4.1
symmetrical monopole
a single VSC converter with symmetrical d.c. voltage output on the two terminals
3.4.2
asymmetrical monopole
a single VSC converter with asymmetrical d.c. voltage output on the two terminals, normally

with one terminal earthed
3.4.3
bipole
two or more VSC asymmetrical monopoles forming a bipolar d.c. circuit
3.4.4
two-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between two
discrete d.c. voltage levels
3.4.5
three-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
three discrete d.c. voltage levels

TR 62543  IEC:2011+A1:2013(E) – 11 –

3.4.6
multi-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between

more than three discrete d.c. voltage levels

3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve consists of a number of self-contained, single-

phase voltage sourced converters MMC building blocks connected in series

3.4.8
VSC unit
three VSC phase units, together with VSC unit control equipment, essential protective and
switching devices, d.c. storage capacitors, valve reactor and auxiliaries, if any, used for
conversion
3.4.9
VSC phase unit
the equipment used to connect the two d.c. busbars to one a.c. terminal
NOTE In the simplest implementation, the VSC phase unit consists of two VSC valves. In some case, it consists
of two VSC valves and valve reactors. The VSC phase unit may also include control and protection equipment, and
other components.
3.4.10
VSC valve
complete controllable device assembly, which represents a functional unit as part of a VSC
phase unit and characterized by switching actions of the power electronic devices upon
control signals of the converter base electronics
NOTE Dependent on the converter topology, a valve can either have the function to act like a controllable switch
or to act like a controllable voltage source.
3.4.10.1
switch type VSC valve
arrangement of IGBT-diode pairs connected in series and arranged to be switched
simultaneously as a single function unit
3.4.10.2
controllable voltage source type VSC valve
complete controllable voltage source assembly, which is generally connected between one
a.c. terminal and one d.c. terminal

3.4.11
diode valve
a semiconductor valve containing diodes but no switched as the main semiconductor devices
and associated circuits and components if any, which might be used in some VSC topologies
3.4.12
valve
refers to VSC valve or diode valve according to the context
3.4.13
VSC valve level
part of a VSC valve comprising a controllable switch and an associated diode, or controllable
switches and diodes connected in parallel, or controllable switches and diodes connected to a
half bridge or full bridge arrangement, together with their immediate auxiliaries, storage
capacitor, if any
– 12 – TR 62543  IEC:2011+A1:2013(E)

NOTE In the context of modular multi-level converters, the term “submodule” is also used to refer to a VSC valve

level.
the smallest indivisible functional unit of VSC valve

NOTE 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. For MMC type without IGBT-diode pairs connected in series
one valve level is one submodule together with its auxiliaries.

3.4.14
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any

3.4.15
redundant levels
the maximum number of series connected of VSC valve levels or diode valve levels in a valve
that may be short-circuited externally or internally during service without affecting the safe
operation of the valve as demonstrated by type tests, and which if, and when exceeded,
would require shutdown of the valve to replace the failed levels or acceptance of increased
risk of failures
NOTE In valve designs such as the cascaded two-level converter, which contain two or more conduction paths
within each cell and have series-connected VSC valve levels in each path, redundant levels shall be counted only
in one conduction path in each cell.
3.4.16
valve protective blocking
means of protecting the valve or converter from excessive electrical stress by the emergency
turn-off of all IGBTs in one or more valves
3.4.17
submodule d.c. capacitor
a capacitor (if any) used as part of a certain VSC valve level, which is used as energy storage
d.c. source voltage sourced converter which experiences mainly d.c. voltage between its
terminals
NOTE For valves of the controllable switch type, the d.c. capacitor is usually arranged as a single device between
the d.c. terminals. For valves of the controllable voltage-sourced type, the d.c. capacitor is usually distributed
amongst the MMC building blocks.
3.4.18
valve reactor
a reactor (if any) which is connected in series to the VSC valve of the controllable voltage-
source type.
NOTE At present valve reactors are used in converter topologies with valves acting like a controllable voltage

source only.One or more valve reactors can be associated to one VSC valve and might be connected at different
positions within the valve. According to the definition, valve reactors are not part of the VSC valve. However, it is
also possible to integrate the valve reactors in the structural design of the VSC valve, e.g. into each valve level
3.4.19
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potentialstructural components of a valve, required in order to physically support
the valve modules
3.4.20
valve support
that part of the valve which mechanically supports and electrically insulates the active part of
the valve from earth
NOTE A part of a valve which is clearly identifiable in a discrete form to be a valve support may not exist in all
designs of valves.
TR 62543  IEC:2011+A1:2013(E) – 13 –

3.4.21
multiple valve unit
MVU
mechanical arrangement of 2 or more valves or 1 or more VSC phase units sharing a common

valve support, where applicable

NOTE A MVU might not exist in all topologies and physical arrangement of converters.

3.4.22
valve section
electrical assembly, defined for test purposes, composing a number of VSC or diode valve

levels and other components, which exhibits pro-rated electrical properties of a complete

valve
NOTE For valves of controllable voltage source type, the valve section shall include d.c. capacitor in addition to
VSC valve levels.
3.4.23
valve base electronics
VBE
electronic unit, at earth potential, which is the interface providing the electrical to optical
conversion between the converter control system and the VSC valves
3.4.24
MMC building block
self-contained, two-terminal controllable voltage source together with d.c. capacitor(s) and
immediate auxiliaries, forming part of a MMC
3.4.25
cascaded two-level (CTL) converter
modular multi-level converter in which each switch position consists of more than one IGBT-
diode pair connected in series
3.4.26
submodule
MMC building block where each switch position consists of only one IGBT-diode pair
3.4.27
cell
MMC building block where each switch position consists of more than one IGBT-diode pair
connected in series
3.5 VSC transmission
3.5.1
VSC substation
part of a VSC transmission scheme, consisting of one or more VSC unit(s) installed in a single
location together with buildings, VSC d.c. capacitors, reactors, transformers, filters, control,
monitoring, protective, measuring and auxiliary equipment, as applicable
3.5.2
interface transformer
transformer (if any) through which power is transmitted between the a.c. system connection
point and one or more VSC units
3.5.3
phase reactor
a reactor connected directly to the a.c. terminal of the VSC phase unit, and combined with
interface transformer leakage reactance (if any), in order to provide the commutating
reactance forming part of the coupling inductance

– 14 – TR 62543  IEC:2011+A1:2013(E)

3.5.4
VSC d.c. capacitor
capacitor bank (s) (if any) connected between two d.c. terminals of the VSC, used as energy

storage and / or filtering purposes

3.5.5
a.c. system side harmonic filters

a filter circuits (if any) used to prevent VSC-generated harmonics generated by the VSC – if

applicable – from penetrating into the a.c. system or to prevent amplification of background

harmonics on the a.c. system. The filter can be located at the point of common coupling
(outside the interface transformer) or/ and on the valve side (inside the interface transformer)

NOTE AC harmonic filters can be installed on either the line side or the converter side of the interface
transformer.
3.5.6
a.c. side radio frequency interference filter (RFI filter)
filters (if any) used to reduce penetration of radio frequency interference (RFI) into the a.c.
system to an acceptable level
3.5.7
high frequency filter
HF-blocking filter
filters (if any) used to reduce penetration of circuits to prevent VSC-generated high frequency
(HF) harmonics – if applicable – from penetrating into the a.c. system to an acceptable level
NOTE High frequency filters can be installed on either the line side or the converter side of the interface
transformer.
3.5.8
valve side harmonic filter
filters (if any) used to mitigate the HF stresses of the interface transformer
3.5.9
common mode blocking reactor
a reactor (if any) used to reduce common mode harmonic currents flowing into a d.c.
overhead line or cable of a bipolar long distance an HVDC transmission scheme
3.5.10
d.c. harmonic filter
d.c. filters (if any) used to prevent harmonics generated by VSC valve from penetrating into
the d.c. system.
NOTE The filter can consist of a tuned shunt branch, smoothing reactor or common mode blocking reactor or
combinations thereof.
3.5.11
d.c. reactor
a reactor (if any) connected in series to a d.c. overhead transmission line or cable busbar
NOTE DC reactor is used to reduce harmonic currents flowing
...

IEC TR 62543 ®
Edition 1.2 2017-05
CONSOLIDATED VERSION
TECHNICAL
REPORT
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inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
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IEC TR 62543 ®
Edition 1.2 2017-05
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced

converters (VSC)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200; 29.240.99 ISBN 978-2-8322-4416-6

IEC TR 62543 ®
Edition 1.2 2017-05
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
High-voltage direct current (HVDC) power transmission using voltage sourced
converters (VSC)
– 2 – IEC TR 62543:2011+AMD1:2013

+AMD2:2017 CSV  IEC 2017
CONTENTS
FOREWORD . 6

1 Scope . 8

2 Normative references . 8

3 Terms and definitions . 8

3.1 General . 8

3.2 Letter symbols . 11

3.3 Power semiconductor terms .

3.4 VSC topologies .
3.5 VSC transmission . 14
3.6 Operating states .
3.7 Type tests . 16
3.8 Production tests . 17
3.9 Sample tests . 17
3.10 Insulation co-ordination terms .
3.11 Power losses . 17
4 VSC transmission overview . 18
4.1 Basic operating principles of VSC transmission . 18
4.1.1 The voltage sourced converter as a black box . 18
4.1.2 The principles of active and reactive power control . 19
4.1.3 Operating principles of a VSC transmission scheme . 21
4.1.4 Applications of VSC transmission . 22
4.2 Design life . 22
4.3 VSC transmission configurations . 22
4.3.1 General . 22
4.3.2 D.C. circuit configurations . 23
4.3.3 Monopole configuration . 23
4.3.4 Bipolar configuration . 24
4.3.5 Parallel connection of two converters . 25
4.3.6 Series connection of two converters . 26
4.3.7 Parallel and series connection of more than two converters . 26
4.4 Semiconductors for VSC transmission . 27
5 VSC transmission converter topologies . 28

5.1 General . 28
5.2 Converter topologies with VSC valves of “switch” type . 29
5.2.1 General . 29
5.2.2 Operating principle . 29
5.2.3 Topologies . 30
5.3 Converter topologies with VSC valves of the “controllable voltage source”
type . 33
5.3.1 General . 33
5.3.2 MMC topology with VSC levels in half-bridge topology . 35
5.3.3 MMC topology with VSC levels in full-bridge topology . 37
5.3.4 CTL topology with VSC cells in half-bridge topology . 38
5.3.5 CTL topology with VSC cells in full-bridge topology . 39
5.4 VSC valve design considerations . 39
5.4.1 Reliability and failure mode . 39

+AMD2:2017 CSV  IEC 2017
5.4.2 Current rating . 39

5.4.3 Transient current and voltage requirements . 39

5.4.4 Diode requirements . 40

5.4.5 Additional design details . 41

5.5 Other converter topologies . 41

5.6 Other equipment for VSC transmission schemes . 41

5.6.1 General . 41

5.6.2 Power components of a VSC transmission scheme . 42

5.6.3 VSC substation circuit breaker . 42

5.6.4 A.C. system side harmonic filters . 42

5.6.5 Radio frequency interference filters . 42
5.6.6 Interface transformers and phase reactors . 43
5.6.7 Valve reactor . 43
5.6.8 D.C. capacitors . 44
5.6.9 D.C. reactor . 46
5.6.10 Common mode blocking reactor . 46
5.6.11 D.C. filter . 46
5.6.12 Dynamic braking system . 46
6 Overview of VSC controls . 47
6.1 General . 47
6.2 Operational modes and operational options . 47
6.3 Power transfer . 48
6.3.1 General . 48
6.3.2 Telecommunication between converter stations . 49
6.4 Reactive power and a.c. voltage control . 49
6.4.1 A.C. voltage control . 49
6.4.2 Reactive power control . 50
6.5 Black start capability . 50
6.6 Supply from a wind farm . 51
7 Steady state operation . 51
7.1 Steady state capability . 51
7.2 Converter power losses . 52
8 Dynamic performance . 53
8.1 A.C. system disturbances . 53
8.2 D.C. system disturbances . 54

8.2.1 D.C. cable fault . 54
8.2.2 D.C. overhead line fault . 54
8.3 Internal faults . 54
9 HVDC performance requirements . 55
9.1 Harmonic performance . 55
9.2 Wave distortion . 56
9.3 Fundamental and harmonics . 56
9.3.1 Three-phase 2-level VSC . 56
9.3.3 Multi-pulse and multi-level converters . 59
9.4 Harmonic voltages on power systems due to VSC operation . 59
9.5 Design considerations for harmonic filters (a.c. side) . 60
9.6 D.C. side filtering . 60
10 Environmental impact . 60

– 4 – IEC TR 62543:2011+AMD1:2013

+AMD2:2017 CSV  IEC 2017
10.1 General . 60

10.2 Audible noise . 61

10.3 Electric and magnetic fields (EMF) . 61

10.4 Electromagnetic compatibility (EMC) . 61

11 Testing and commissioning . 62

11.1 General . 62

11.2 Factory tests . 62

11.2.1 Component tests . 62

11.2.2 Control system tests . 63

11.3 Commissioning tests / System tests . 63
11.3.1 General . 63
11.3.2 Precommissioning tests . 63
11.3.3 Subsystem tests . 64
11.3.4 System tests . 64
Annex A (informative) Functional specification requirements for VSC transmission
systems . 69
Annex B (informative) Determination of VSC valve power losses .
Annex B (informative) Modulation strategies for 2-level converters . 86
Bibliography . 89

Figure 1 – Major components that may be found in a VSC substation . 10
Figure 2 – Diagram of a generic voltage source converter (a.c. filters not shown) . 18
Figure 3 – The principle of active power control . 20
Figure 4 – The principle of reactive power control . 21
Figure 5 – A point-to-point VSC transmission scheme . 21
Figure 6 – VSC transmission with a symmetrical monopole . 23
Figure 7 – VSC transmission with an asymmetrical monopole with metallic return . 24
Figure 8 – VSC transmission with an asymmetrical monopole with earth return . 24
Figure 9 – VSC transmission in bipolar configuration . 25
Figure 10 – Parallel connection of two converter units . 26
Figure 11 – Symbol of a controllable switch turn-off semiconductor device and
associated free-wheeling diode . 27
Figure 12 – Symbol of an IGBT and associated free-wheeling diode . 27

Figure 13 – Diagram of a three-phase 2-level converter and associated a.c. waveform
for one phase. 30
Figure 14 – Single-phase a.c. output for 2-level converter with PWM switching at 21
times fundamental frequency . 31
Figure 15 – Diagram of a three-phase 3-level NPC converter and associated a.c.
waveform for one phase . 32
Figure 16 – Single-phase a.c. output for 3-level NPC converter with PWM switching at
21 times fundamental frequency . 33
Figure 17 – Electrical equivalent for a converter with VSC valves acting like a
controllable voltage source . 34
Figure 18 – VSC valve level arrangement and equivalent circuit in MMC topology in
half-bridge topology . 35
Figure 19 – Converter block arrangement with MMC topology in half-bridge topology . 37

+AMD2:2017 CSV  IEC 2017
Figure 20 – VSC valve level arrangement and equivalent circuit in MMC topology with

full-bridge topology . 38

Figure 21 – Typical SSOA for the IGBT . 40

Figure 22 – A 2-level VSC bridge with the IGBTs turned off . 40

Figure 23 – Representing a VSC unit as an a.c. voltage of magnitude U and phase

angle δ behind reactance . 47

Figure 24 – Concept of vector control . 48

Figure 25 – VSC power controller . 49

Figure 26 – A.C. voltage controller . 50

Figure 27 – A typical simplified PQ diagram . 52
Figure 28 – Protection concept of a VSC substation. 55
Figure 29 – Waveforms for three-phase 2-level VSC . 57
Figure 30 – Voltage harmonics spectra of a 2-level VSC with carrier frequency at 21st
harmonic .
Figure 31 – Phase output voltage for selective harmonic elimination modulation
(SHEM) .
Figure 32 – Equivalent circuit at the PCC of the VSC . 60
Figure B.1 – On state voltage of an IGBT or free-wheeling diode .
st
Figure B.1 – Voltage harmonics spectra of a 2-level VSC with carrier frequency at 21
harmonic . 87
Figure B.2 – Piecewise-linear representation of IGBT or FWD on-state voltage .
Figure B.2 – Phase output voltage for selective harmonic elimination modulation
(SHEM) . 88
Figure B.3 – IGBT switching losses as a function of collector current .
Figure B.4 – Free-wheeling diode recovery loss as a function of current .

– 6 – IEC TR 62543:2011+AMD1:2013

+AMD2:2017 CSV  IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

FOREWORD
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This consolidated version of the official IEC Standard and its amendments has been prepared
for user convenience.
IEC TR 62543 edition 1.2 contains the first edition (2011-03) [documents 22F/230/DTR and
22F/239A/RVC], its amendment 1 (2013-07) [documents 22F/300A/DTR and 22F/307/RVC] and its
amendment 2 (2017-05) [documents 22F/440/DTR and 22F/450/RVDTR].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendments 1 and 2. Additions are in green text, deletions are in
strikethrough red text. A separate Final version with all changes accepted is available in this
publication.
+AMD2:2017 CSV  IEC 2017
The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".
IEC/TR 62543, which is a technical report, has been prepared by subcommittee 22F: Power
electronics for electrical transmission and distribution systems, of IEC technical committee 22:

Power electronic systems and equipment.

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

The committee has decided that the contents of the base publication and its amendments 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.
A bilingual version of this publication may be issued at a later date.

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
understanding of its contents. Users should therefore print this document using a
colour printer.
– 8 – IEC TR 62543:2011+AMD1:2013

+AMD2:2017 CSV  IEC 2017
HIGH-VOLTAGE DIRECT CURRENT (HVDC) POWER TRANSMISSION

USING VOLTAGE SOURCED CONVERTERS (VSC)

1 Scope
This technical report gives general guidance on the subject of voltage-sourced converters
used for transmission of power by high voltage direct current (HVDC). It describes converters
that are not only voltage-sourced (containing a capacitive energy storage medium and where

the polarity of d.c. voltage remains fixed) but also self-commutated, using semiconductor
devices which can both be turned on and turned off by control action. The scope includes
2-level and 3-level converters with pulse-width modulation (PWM), along with multi-level
converters, modular multi-level converters and cascaded two-level converters, but excludes 2-
level and 3-level converters operated without PWM, in square-wave output mode.
HVDC power transmission using voltage sourced converters is known as “VSC transmission”.
The various types of circuit that can be used for VSC transmission are described in the report,
along with their principal operational characteristics and typical applications. The overall aim
is to provide a guide for purchasers to assist with the task of specifying a VSC transmission
scheme.
Line-commutated and current-sourced converters are specifically excluded from this report.
2 Normative references
The following referenced documents are indispensable for the application 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 60633, Terminology for high-voltage direct-current (HVDC) transmission
IEC 61975, High-voltage direct current (HVDC) installations – System tests
IEC 62501, Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing
IEC 62747, Terminology for voltage-sourced converters (VSC) for high-voltage direct current

(HVDC) systems
IEC 62751 (all parts), Power losses in voltage sourced converter (VSC) valves for high
voltage direct current (HVDC) systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62747, IEC 62501
and the following apply.
3.1 General
Basic terms and definitions for voltage sourced converters used for HVDC transmission are
given in IEC 62747. Terminology on electrical testing of VSC valves for HVDC transmission is
given in IEC 62501.
+AMD2:2017 CSV  IEC 2017
NOTE This report uses the terminology established by IEC 60633 and IEC 61803 for line-commutated HVDC.

Only terms which are specific to HVDC transmission using voltage sourced converters are defined in this clause.
Those terms that are either identical to or obvious extensions of IEC 60633 or IEC 61803 terminology have not

been defined.
To support the explanations, Figure 1 presents the basic diagram of a VSC system.

Dependent on the converter topology and the requirements in the project, some components

can be omitted or can differ.
~
DC line of
j
the second pole
=
k
a b c d e f g h i l m n o
IEC  567/11
b
a circuit breaker i VSC d.c. capacitor
b line side harmonic filter j d.c. harmonic filter
c
c line side high frequency filter k neutral point grounding branch
d
d interface transformer l d.c. reactor
d
e converter side harmonic filter m common mode blocking reactor
a d
f + g converter side high frequency filter n d.c. side high frequency filter
a b
g phase reactor o d.c. cable or overhead transmission line

h VSC unit
a
In some designs of VSC, the phase reactor may fulfil part of the function of the converter-side high frequency
filter. In addition, in some designs of VSC, part of or all of the phase reactor may be built into the three “Phase
units” of the VSC unit, as “Valve reactors”.
b
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 the d.c. submodule capacitors.
c
The location of the neutral point grounding branch may be different depending on the design of the VSC unit.
d
Not normally required for back-to-back systems.

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IEC
3)
1 circuit breaker 9 VSC unit
4)
2 pre-Insertion Resistor 10 VSC d.c. capacitor

1) 1)
3 line side harmonic filter 11 d.c. harmonic filter
6) 7)
4 line side high frequency filter 12 dynamic braking system
5)
5 interface transformer 13 neutral point grounding branch
1) 8)
6 converter side harmonic filter 14 d.c. reactor
2)
7 + 8 converter side high frequency filter 15 d.c. cable or overhead transmission line
2)
8 phase reactor
1)
In some designs of VSC based on "controllable voltage source" valves, the harmonic filters may not be

required.
2)
In some designs of VSC, the phase reactor may fulfill part of the function of the converter-side high frequency
filter.
3)
In some VSC topologies, each valve of the VSC unit may include a "valve reactor", which may be built into the
valve or provided as a separate component.
4)
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 the d.c. submodule capacitors.

5)
The philosophy and location of the neutral point grounding branch may be different depending on the design of
the VSC unit.
6)
In some designs of VSC, the interface transformer may fulfill part of the function of the line-side high frequency
filter.
7)
Optional.
8)
Optional, if phase reactors are located on the d.c. side of the converter.
Figure 1 – Major components that may be found in a VSC substation

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3.2 Letter symbols
line-to-line a.c. voltage of the converter unit(s), r.m.s. value, including
U
conv
harmonics;
alternating current of the converter unit(s), r.m.s. value, including

I
conv
harmonics;
line-to-line a.c. voltage of the a.c. system, r.m.s. value, including
U
L
harmonics;
I alternating current of the a.c. system, r.m.s. value, including harmonics;
L
U d.c. line-to-line voltage of the d.c. bus of the VSC transmission system;
d
I d.c. current of the d.c. bus of the VSC transmission system.
d
3.3 Power semiconductor terms
NOTE There are several types of switched valve devices which can be used in voltage sourced converters (VSC)
for HVDC and currently the IGBT is the major device used in such converters. The term IGBT is used throughout
this technical report to refer to the switched valve device. However, the technical report is equally applicable to
other types of devices with turn-off capability in most of the parts.
3.3.1
switched valve devices
a controllable valve device which may be turned on and off by a control signal, for example
IGBT
3.3.2
insulated gate bipolar transistor
IGBT
a controllable switch with the capability to turn-on and turn-off a load current. An IGBT has
three terminals: a gate terminal (G) and two load terminals emitter (E) and collector (C).
3.3.3
free-wheeling diode
FWD
power semiconductor device with diode characteristic
3.3.4
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.4 VSC topologies
3.4.1
symmetrical monopole
a single VSC converter with symmetrical d.c. voltage output on the two terminals
3.4.2
asymmetrical monopole
a single VSC converter with asymmetrical d.c. voltage output on the two terminals, normally
with one terminal earthed
3.4.3
bipole
two or more VSC asymmetrical monopoles forming a bipolar d.c. circuit

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3.4.4
two-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between two

discrete d.c. voltage levels
3.4.5
three-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between

three discrete d.c. voltage levels

3.4.6
multi-level converter
a converter in which the voltage at the a.c. terminals of the VSC unit is switched between
more than three discrete d.c. voltage levels
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve consists of a number of self-contained, single-
phase voltage sourced converters connected in series
3.4.8
VSC unit
three VSC phase units, together with VSC unit control equipment, essential protective and
switching devices, d.c. storage capacitors, valve reactor and auxiliaries, if any, used for
conversion
3.4.9
VSC phase unit
the equipment used to connect the two d.c. busbars to one a.c. terminal
NOTE In the simplest implementation, the VSC phase unit consists of two VSC valves. In some case, it consists
of two VSC valves and valve reactors. The VSC phase unit may also include control and protection equipment, and
other components.
3.4.10
VSC valve
complete controllable device assembly, which represents a functional unit as part of a VSC
phase unit and characterized by switching actions of the power electronic devices upon
control signals of the converter base electronics
NOTE Dependent on the converter topology, a valve can either have the function to act like a controllable switch
or to act like a controllable voltage source.

3.4.11
diode valve
a semiconductor valve containing diodes but no switched semiconductor devices, which might
be used in some VSC topologies
3.4.12
valve
refers to VSC valve or diode valve according to the context
3.4.13
VSC valve level
part of a VSC valve comprising a controllable switch and an associated diode, or controllable
switches and diodes connected in parallel, or controllable switches and diodes connected to a
half bridge or full bridge arrangement, together with their immediate auxiliaries, storage
capacitor, if any
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NOTE In the context of modular multi-level converters, the term “submodule” is also used to refer to a VSC valve

level.
3.4.14
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any

3.4.15
redundant levels
the maximum number of VSC valve levels or diode valve levels in a valve that may be short-

circuited externally or internally during service without affecting the safe operation of the

valve as demonstrated by type tests, and which if and when exceeded, would require

shutdown of the valve to replace the failed levels or acceptance of increased risk of failures
3.4.16
valve protective blocking
means of protecting the valve or converter from excessive electrical stress by the emergency
turn-off of all IGBTs in one or more valves
3.4.17
submodule d.c. capacitor
a capacitor (if any) used as part of a certain VSC valve level, which is used as energy storage
d.c. source
3.4.18
valve reactor
a reactor (if any) which is connected in series to the VSC valve. One or more valve reactors
can be associated to one VSC valve and might be connected at different positions within the
valve. According to the definition, valve reactors are not part of the VSC valve. However, it is
also possible to integrate the valve reactors in the structural design of the VSC valve, e.g. into
each valve level.
NOTE At present valve reactors are used in converter topologies with valves acting like a controllable voltage
source only.
3.4.19
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.4.20
valve support
that part of the valve which mechanically supports and electrically insulates the active part of

the valve from earth
NOTE A part of a valve which is clearly identifiable in a discrete form to be a valve support may not exist in all
designs of valves.
3.4.21
multiple valve unit
MVU
mechanical arrangement of 2 or more valves or 1 or more VSC phase units sharing a common
valve support
NOTE A MVU might not exist in all topologies and physical arrangement of converters.
3.4.22
valve section
electrical assembly, composing a number of VSC or diode valve levels and other components,
which exhibits pro-rated electrical properties of a complete valve

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3.4.23
valve base electronics
VBE
electronic unit, at earth potential, which is the interface between the converter control system

and the VSC valves
3.5 VSC transmission
3.5.1
VSC substation
part of a VSC transmission scheme, consisting of one or more VSC unit(s) installed in a single

location together with buildings, VSC d.c. capacitors, reactors, transformers, filters, control,

monitoring, protective, measuring and auxiliary equipment, as applicable
3.5.2
interface transformer
transformer (if any) through which power is transmitted between the a.c. system connection
point and one or more VSC units
3.5.3
phase reactor
reactor connected directly to the a.c. terminal of the VSC phase unit, and combined with
interface transformer leakage reactance (if any), in order to provide the commutating
reactance
3.5.4
VSC d.c. capacitor
capacitor bank (s) (if any) connected between two d.c. terminals of the VSC, used as energy
storage and / or filtering purposes
3.5.5
a.c. system side harmonic filter
filter (if any) used to prevent harmonics generated by the VSC from penetrating into the a.c.
system. The filter can be located at the point of common coupling (outside the interface
transformer) or/ and on the valve side (inside the interface transformer)
3.5.6
a.c. side radio frequency interference filter (RFI filter)
filters (if any) used to reduce penetration of radio frequency interference (RFI) into the a.c.
system to an acceptable level
3.5.7
HF-blocking filter
filters (if any) used to reduce penetration of high frequency (HF) harmonics into the a.c.
system to an acceptable level
3.5.8
valve side harmonic filter
filters (if any) used to mitigate the HF stresses of the interface transformer
3.5.9
common mode blocking reactor
a reactor (if any) used to reduce common mode harmonic currents flowing into a d.c.
overhead line or cable of a bipolar long distance transmission scheme
3.5.10
d.c. harmonic filter
d.c. filters (if any) used to prevent harmonics generated by VSC valve from penetrating into
the d.c. system.
+AMD2:2017 CSV  IEC 2017
NOTE The filter can consist of a tuned shunt branch, smoothing reactor or common mode blocking reactor or

combinations thereof.
3.5.11
d.c. reactor
a reactor (if any) connected in series to a d.c. overhead transmission line or cable busbar

NOTE DC reactor is used to reduce harmonic currents flowing in the d.c. line or cable and to detune critical

resonances within the d.c. circuit. A d.c. reactor might also be used for protection purposes.

3.5.12
d
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