IEC 62927:2017
(Main)Voltage sourced converter (VSC) valves for static synchronous compensator (STATCOM) - Electrical testing
Voltage sourced converter (VSC) valves for static synchronous compensator (STATCOM) - Electrical testing
IEC 62927:2017 applies to self-commutated valves, for use in voltage sourced converter (VSC) for static synchronous compensator (STATCOM). It is restricted to electrical type and production tests.
The tests specified in this document are based on air insulated valves. For other types of valves, the test requirements and acceptance criteria are agreed between the purchaser and the supplier.
The contents of the corrigendum of December 2017 have been included in this copy.
Valves de convertisseur source de tension (VSC) pour compensateur synchrone statique (STATCOM) - Essais électriques
L'IEC 62927:2017 s'applique aux valves autocommutées, conçues pour être utilisées dans un convertisseur source de tension (VSC) pour compensateur synchrone statique (STATCOM). Elle se limite aux essais de type électrique et de production.
Les essais spécifiés dans le présent document sont établis pour des valves isolées à l'air. Pour les autres types de valves, les exigences relatives aux essais et les critères d'acceptation font l'objet d'un accord entre le client et le fournisseur.
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Standards Content (Sample)
IEC 62927 ®
Edition 1.0 2017-07
INTERNATIONAL
STANDARD
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
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IEC 62927 ®
Edition 1.0 2017-07
INTERNATIONAL
STANDARD
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.200; 29.240.99 ISBN 978-2-8322-4521-7
– 2 – IEC 62927:2017 © IEC 2017
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 Insulation co-ordination terms . 7
3.2 Power semiconductor terms . 8
3.3 Operating states of converter . 8
3.4 STATCOM construction terms . 9
3.5 Valve structure terms . 10
4 General requirements . 11
4.1 Guidelines for the performance of type tests . 11
4.1.1 General . 11
4.1.2 Dielectric tests . 11
4.1.3 Operational tests . 11
4.1.4 Electromagnetic interference tests . 11
4.1.5 Evidence in lieu . 11
4.1.6 Test object . 12
4.1.7 Test procedure . 12
4.1.8 Ambient temperature for testing . 12
4.1.9 Frequency for testing . 12
4.1.10 Conditions to be considered in determination of type test parameters . 12
4.1.11 Test reports . 12
4.2 Atmospheric correction factor . 12
4.3 Treatment of redundancy . 13
4.3.1 Operational tests . 13
4.3.2 Dielectric tests . 13
4.4 Permissible component failures during type testing . 14
5 List of tests . 14
6 Operational tests . 15
6.1 Purpose of tests . 15
6.2 Test object . 15
6.3 Test circuit . 16
6.4 Maximum continuous operating duty test . 16
6.5 Maximum temporary overload operating duty test . 17
6.6 Minimum start voltage test . 17
7 Dielectric tests on valve support . 18
7.1 Purpose of tests . 18
7.2 Test object . 18
7.3 Test requirements . 18
7.3.1 Valve support DC voltage test. 18
7.3.2 Valve support AC voltage test . 19
7.3.3 Valve support lightning impulse test . 20
8 Dielectric tests on multiple valve unit (MVU) . 20
8.1 General . 20
8.2 Purpose of tests . 20
8.3 Test object . 20
8.4 Test requirements . 20
8.4.1 MVU AC voltage test . 20
8.4.2 MVU DC voltage test . 21
8.4.3 MVU lightning impulse test . 21
9 Dielectric tests between valve terminals . 21
9.1 Purpose of the test . 21
9.2 Test object . 22
9.3 Test methods . 22
9.3.1 General . 22
9.3.2 Method 1 . 22
9.3.3 Method 2 . 23
9.4 Test requirements . 23
9.4.1 Valve AC voltage or AC-DC voltage test . 23
9.4.2 Valve switching impulse test . 25
10 IGBT overcurrent turn-off test . 26
10.1 Purpose of test . 26
10.2 Test object . 26
10.3 Test requirements . 26
11 Tests for valve insensitivity to electromagnetic disturbance . 27
11.1 Purpose of tests . 27
11.2 Test object . 27
11.3 Test requirements . 27
11.3.1 General . 27
11.3.2 Approach 1 . 27
11.3.3 Approach 2 . 28
11.3.4 Acceptance criteria . 28
12 Short-circuit current test (optional). 28
12.1 Purpose of tests . 28
12.2 Test object . 28
12.3 Test requirements . 29
13 Production tests. 29
13.1 General . 29
13.2 Purpose of tests . 29
13.3 Test object . 29
13.4 Test requirements . 29
13.5 Production test objectives . 30
13.5.1 Visual inspection . 30
13.5.2 Connection check . 30
13.5.3 Voltage-grading circuit check . 30
13.5.4 Control, protection and monitoring circuit checks . 30
13.5.5 Voltage withstand check . 30
13.5.6 Turn-on/turn-off check . 30
13.5.7 Pressure test . 30
14 Presentation of type test results . 30
Annex A (informative) Overview of STATCOM valves . 32
A.1 General . 32
A.2 STATCOM applications and operating limits . 32
A.3 Overview of STATCOM valve types. 33
– 4 – IEC 62927:2017 © IEC 2017
A.4 STATCOMs based on switch type valve . 33
A.4.1 General . 33
A.4.2 Two-level converter . 34
A.4.3 Three-level converters . 34
A.4.4 Multi-level converters. 35
A.5 STATCOMs based on controllable voltage source type valve . 36
A.6 Valve switching principles . 37
Annex B (informative) Valve component fault tolerance. 39
Bibliography . 40
Figure A.1 – STATCOM U-I characteristics . 33
Figure A.2 – Two-level converter . 34
Figure A.3 – Three-level NPC converter . 35
Figure A.4 – Three-level flying capacitor converter . 35
Figure A.5 – Modular multilevel converter . 36
Figure A.6 – Single-phase full-bridge converter. 37
Figure A.7 – Two-level converter output voltage . 37
Figure A.8 – Output voltage shape of three-level converter and modular multi-level
converter . 38
Table 1 – Minimum number of valve levels to be tested as a function of the number of
valve levels per valve . 12
Table 2 – Valve level faults permitted during type tests . 14
Table 3 – List of type tests . 15
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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International Standard IEC 62927 has been prepared by subcommittee 22F: Power
electronics for electrical transmission and distribution systems, of IEC technical committee 22:
Power electronic systems and equipment.
The text of this International Standard is based on the following documents:
CDV Report on voting
22F/412/CDV 22F/431A/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
– 6 – IEC 62927:2017 © IEC 2017
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of December 2017 have been included in this copy.
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.
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
1 Scope
This document applies to self-commutated valves, for use in voltage sourced converter (VSC)
for static synchronous compensator (STATCOM). It is restricted to electrical type and
production tests.
The tests specified in this document are based on air insulated valves. For other types of
valves, the test requirements and acceptance criteria are agreed between the purchaser and
the supplier.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60060 (all parts), High-voltage test techniques
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1:2006, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power transmission
– Part 1: Electrical testing
IEC 62501, Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Insulation co-ordination terms
3.1.1
test withstand voltage
value of a test voltage of standard waveshape at which a new valve, with unimpaired integrity,
does not show any disruptive discharge and meets all other acceptance criteria specified for
the particular test, when subjected to a specified number of applications or a specified
duration of the test voltage, under specified conditions
– 8 – IEC 62927:2017 © IEC 2017
3.1.2
internal insulation
air external to the components and insulating materials of the valve, but contained within the
profile of the valve or multiple valve unit
3.1.3
external insulation
air between the external surface of the valve or multiple valve unit and its surroundings
3.2 Power semiconductor terms
3.2.1
turn-off semiconductor device
controllable semiconductor device which may be turned on and off by a control signal, for
example an IGBT
Note 1 to entry: There are several types of turn-off semiconductor devices, for example IGBT, IGCT and GTO,
which can be used in voltage sourced converters for STATCOM. For convenience, the term IGBT is used
throughout this document to refer to the main, controllable turn-off, semiconductor device. However, this document
is equally applicable to other types of controllable semiconductor switch device.
3.2.2
gate turn-off thyristor
GTO thyristor
turn-off semiconductor device which can be turned on and off by its gate lead
Note 1 to entry: A GTO thyristor is a special type of thyristor, which is a high-power semiconductor device.
Note 2 to entry: Gate commutated thyristor (GCT) and integrated gate commutated thyristor (IGCT) are special
types of GTO thyristor.
3.2.3
insulated gate bipolar transistor
IGBT
transistor provided for power switching having a conduction channel and a PN junction and in
which the current flowing through the channel and the junction is controlled by an electric field
resulting from a voltage applied between the gate and emitter terminals
3.2.4
free-wheeling diode
FWD
power semiconductor device with diode characteristic connected to an insulated gate bipolar
transistor (IGBT) in inverse parallel
Note 1 to entry: An FWD has two terminals: an anode (A) and a cathode (K).
Note 2 to entry: The current through FWDs is in the opposite direction to the IGBT current.
Note 3 to entry: Concepts of "inverse parallel" and "anti-parallel" are identical.
3.2.5
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.3 Operating states of converter
3.3.1
blocking state
condition of the converter, in which a turn-off signal is applied continuously to all IGBTs of the
converter
3.3.2
de-blocked state
condition of the converter, in which turn-on and turn-off signals are applied repetitively to
IGBTs of the converter
3.3.3
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
3.3.4
voltage step level
voltage step caused by switching of a valve or part of a valve during the de-blocked state of
the converter
Note 1 to entry: For a voltage source type valve, one half bridge cell corresponds to one voltage step level and a
full bridge cell has two voltage step levels.
3.4 STATCOM construction terms
3.4.1
STATCOM
shunt connected reactive compensation equipment which is capable of generating and/or
absorbing reactive power, whose capacitive or inductive output current can be controlled
independently of the AC system voltage
Note 1 to entry: Previous alternative terms for the STATCOM have included static var generator (SVG), advanced
static var compensator (ASVC) and static synchronous condenser (STATCON).
3.4.2
STATCOM valve
electrically and mechanically combined assembly of IGBT levels, complete with all
connections, auxiliary components and mechanical structures, which can be connected in
series with each phase of reactor of a STATCOM
Note 1 to entry: Depending 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. For controllable voltage source type converter, the
STATCOM controllable voltage source type valve is a complete controllable voltage source assembly, which is
generally connected between two AC phases. For switch type converter, the STATCOM switch type valve is an
arrangement of IGBTs connected in series and arranged to be switched simultaneously as a single function unit
between one AC phase and one DC terminal of the DC capacitor energy storage.
Note 2 to entry: For convenience, the term "STATCOM valve" is shortened as "valve" in this document.
3.4.3
diode valve
semiconductor valve containing only diodes as the main semiconductor devices, which might
be used in some STATCOM topologies
3.4.4
submodule
part of a valve comprising controllable switches and diodes connected in a half bridge or full
bridge arrangement, together with their immediate auxiliaries, storage capacitor, if any, where
each controllable switch consists of one or more switched valve device(s) connected in series
Note 1 to entry: This definition is only applicable for converters of controllable voltage source type.
3.4.5
switch type valve
arrangement of IGBT-diode pairs connected in series and arranged to be switched
simultaneously as a single function unit
– 10 – IEC 62927:2017 © IEC 2017
3.4.6
controllable voltage source type valve
complete controllable voltage source assembly, which is generally connected between AC
phases or between one AC terminal and one DC terminal
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve (see 3.4.5, 3.4.6) consists of a number of MMC
building blocks (see 3.4.9) connected in series
3.4.8
cascaded two-level converter
CTL
modular multi-level converter in which each switch position consists of more than one
IGBT-diode pair connected in series
3.4.9
MMC building block
self-contained, two-terminal controllable voltage source together with DC capacitor(s) and
immediate auxiliaries, forming part of a MMC
3.4.10
STATCOM valve level
the smallest indivisible functional unit of valve
Note 1 to entry: For any valve in which switch devices are connected in series and operated simultaneously, one
valve level is one IGBT including its auxiliaries. For modular multilevel converter (MMC) type without IGBT
connected in series, one valve level is one submodule (cell) together with its auxiliaries.
3.4.11
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.12
redundant valve levels
the maximum number of series connected valve levels or diode valve levels in a valve that
may be short-circuited externally or internally 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 1 to entry: In valve designs 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.
3.5 Valve structure terms
3.5.1
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.5.2
valve support
part of the valve which mechanically supports and electrically insulates the active part of the
valve from earth
3.5.3
multiple valve unit
MVU
mechanical arrangement of two or more valves sharing a common valve support, where
applicable
3.5.4
valve section
electrical assembly defined for test purposes, comprising a number of valve levels and other
components, which exhibits pro-rated electrical properties of a complete valve
3.5.5
valve base electronics
electronic unit, at earth potential, which is the interface between the converter control system
and the STATCOM valves
4 General requirements
4.1 Guidelines for the performance of type tests
4.1.1 General
The tests described apply to the valve (or valve sections), the valve structure and those parts
of the coolant distribution system and firing and monitoring circuits which are contained within
the valve structure (internal insulation) or connected between the valve structure and earth
(external insulation). Other equipment, such as valve control and protection and valve base
electronics, can be essential for demonstrating the correct function of the valve during the
tests but are not in themselves the subject of the tests.
4.1.2 Dielectric tests
The purpose of these tests is to verify the valve design for voltage stresses under normal and
abnormal repetitive conditions as well as under transient conditions.
In the interest of standardization with other equipment, lightning impulse tests between valve
terminals and earth and between phases of a multiple valve unit (MVU) are included. For tests
between valve terminals, the only impulse test specified is a switching impulse.
4.1.3 Operational tests
The purpose of these tests is to verify the valve design for combined voltage and current
stresses under normal and abnormal repetitive conditions as well as under transient fault
conditions.
4.1.4 Electromagnetic interference tests
The principal objective of these tests is to demonstrate the immunity of the valve to
electromagnetic interference from within the valve and from outside the valve.
4.1.5 Evidence in lieu
Each design of valve shall be subjected to the type tests specified in this document. If the
valve is demonstrably similar to one previously tested, the supplier may, in lieu of performing
a type test, submit a test report of a previous type test for consideration by the purchaser.
This should be accompanied by a separate report detailing the differences in the design and
demonstrating how the referenced type test satisfies the test objectives for the proposed
design.
– 12 – IEC 62927:2017 © IEC 2017
4.1.6 Test object
4.1.6 does not apply to tests on the valve support and multiple valve units. The test object for
those tests may be a representative separate object including representation of the adjacent
parts of the valve, or may form part of the assembly used for single valve or multiple valve
unit tests.
a) Type tests may be performed either on a complete valve or, in certain circumstances, on
valve sections, as indicated in Table 3.
b) The minimum number of valve levels to be tested, depending on the valve levels in a
single valve, is as shown in Table 1.
Table 1 – Minimum number of valve levels to be tested as a function
of the number of valve levels per valve
Number of valve levels per valve Total number of valve levels to be tested
1 to 10 Number of valve levels in one valve
11 to 50 10 levels
20% of valve levels in one valve
≥ 51
c) Generally, the same valve sections are recommended to be used for all type tests.
However, with the agreement of the purchaser and supplier, different tests may be
performed on different valve sections in parallel, in order to speed up the programme for
executing the tests.
d) Prior to commencement of type tests, the valve, valve sections and/or the components of
them should be demonstrated to have withstood the production tests to ensure proper
manufacture.
4.1.7 Test procedure
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.8 Ambient temperature for testing
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.9 Frequency for testing
AC dielectric tests can be performed at either 50 Hz or 60 Hz. For operational tests, specific
requirements regarding the frequency for testing are given in the relevant clauses.
4.1.10 Conditions to be considered in determination of type test parameters
Type test parameters should be determined based on the worst operating and fault conditions
to which the valve can be subjected, according to system studies.
4.1.11 Test reports
At the completion of the type tests, the supplier shall provide type test reports in accordance
with Clause 14.
4.2 Atmospheric correction factor
When specified in the relevant clause, atmospheric correction shall be applied to the test
voltages in accordance with IEC 60060-1. The reference conditions to which correction shall
be made are the following.
– Pressure
• If the insulation coordination of the tested part of the valve is based on standard rated
withstand voltages according to IEC 60071-1, correction factors for site conditions are
only applied for altitudes exceeding 1 000 m. Hence, if the altitude of the site a at
s
which the equipment will be installed is ≤ 1 000 m, then the standard atmospheric air
pressure (b = 101,3 kPa) shall be used with no correction for altitude. If a > 1 000 m,
0 s
then the standard procedure according to IEC 60060-1 is used except that the
reference atmospheric pressure b is replaced by the atmospheric pressure
corresponding to an altitude of 1 000 m (b ).
1 000 m
• If the insulation coordination of the tested part of the valve is not based on standard
rated withstand voltages according to IEC 60071-1, then the correction factor for site
conditions follows the standard procedure according to IEC 60060-1 with the reference
atmospheric pressure b (b = 101,3 kPa).
0 0
– Temperature: design maximum valve hall air temperature (°C).
– Humidity: design minimum valve hall absolute humidity (g/m ).
Realistic worst case combinations of temperature and humidity which can occur in practice
shall be used for atmospheric correction.
The values to be used shall be specified by the supplier.
4.3 Treatment of redundancy
4.3.1 Operational tests
For operational tests, redundant valve levels shall not be short-circuited. The test voltages
used shall be adjusted by means of a scaling factor k :
n
N
tut
k =
n
N −N
t r
where
N is the number of series valve levels in the test object;
tut
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
4.3.2 Dielectric tests
For all dielectric tests between valve terminals, the redundant valve levels shall be short-
circuited. The location of valve levels to be short-circuited shall be agreed by the purchaser
and supplier.
NOTE Depending on the design, limitations can be imposed upon the distribution of short-circuited valve levels.
For example, there can be an upper limit to the number of short-circuited valve levels in one valve section.
For all dielectric tests on valve section, the test voltages used shall be adjusted by means of a
scaling factor k :
o
N
tu
k =
o
Ν −Ν
t r
where
N is the number of series valve levels not short circuit connected in the test object;
tu
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
– 14 – IEC 62927:2017 © IEC 2017
4.4 Permissible component failures during type testing
Experience in semiconductor application shows that, even with the most careful design of
valves, it is not possible to avoid occasional random failures of valve level components during
service operation. Even though these failures may be stress-related, they are considered
random to the extent that the cause of failure or the relationship between failure rate and
stress cannot be predicted or is not amenable to precise quantitative definition. Type tests
subject valves or valve sections, within a short time, to multiple stresses that generally
correspond to the worst stresses that can be experienced by the equipment not more than a
few times during the life of the valve. Considering the above, the criteria for successful type
testing set out below therefore permit a small number of valve levels to fail during type
testing, providing that the failures are rare and do not show any pattern that is indicative of
inadequate design and providing the failed valve level permits the rest of the valve or valve
section to continue operating without degraded performance.
The valves or valve sections shall be checked before each test, after any preliminary
calibration tests, and again after each type test to determine whether or not any insulated
gate bipolar transistors (IGBTs) or auxiliary components have failed during the test. Failed
IGBTs or auxiliary components found at the end of a type test shall be remedied before
further testing of a valve.
If, following a type test, one valve level (or more according to Table 2) has become short or
open circuited, then the failed level(s) shall be restored and this type test repeated.
The distribution of short-circuited or open-circuited levels and of other IGBT level faults at the
end of all type tests shall be essentially random and it shall not show any pattern indicative of
inadequate design.
Table 2 – Valve level faults permitted during type tests
Number of valve levels Number of valve levels Total number of valve Additional number of
tested permitted to become levels permitted to valve levels, in all type
short or open circuited become short or open tests, which have
in any one type test circuited in all type experienced a fault but
tests have not become short
or open circuited
Up to 33 1 1 1
34 to 67 1 2 2
68 to 100 1 3 3
2 4 4
> 100
5 List of tests
List of tests is given in the middle column of Table 3.
Table 3 – List of type tests
Test Clause or Test object
subclause
Operational type tests
Maximum continuous operating duty test 6.4 Valve or valve section
Maximum temporary overload operating duty test 6.5 Valve or valve section
Minimum start voltage test 6.6 Valve or valve section
Overcurrent turn-off test 10 Valve or valve section
Short-circuit current test (optional) 12 Valve or valve section
Dielectric type tests
Valve support DC voltage test 7.3.1 Valve support
Valve support AC voltage test 7.3.2 Valve support
Valve support lightning impulse test 7.3.3 Valve support
MVU AC voltage test 8.4.1 MVU
MVU DC voltage test 8.4.2 MVU
MVU lightning impulse test 8.4.3 MVU
Valve AC voltage test 9.4.1.2
Valve AC-DC voltage test 9.4.1.3 Valve or valve section
Valve switching impulse test 9.4.2
Test for valve insensitivity to electromagnetic disturbance
Test for valve insensitivity to electromagnetic 11
Valve or valve section
disturbance
Production tests
Visual inspection 13.5.1
Connection check 13.5.2
Voltage-grading circuit check 13.5.3
Control, protection and monitoring circuit checks 13.5.4
Voltage withstand check 13.5.5
Turn-on/turn-off check 13.5.6
Pressure test 13.5.7
6 Operational tests
6.1 Purpose of tests
The principal objectives of the operational tests are
a) to check the adequacy of the IGBT/diode level and associated electrical circuits in a valve
with regard to current, voltage and temperature stresses in the conducting state, blocking
state, de-blocked state, at turn-on and turn-off under the worst repetitive stress conditions,
and
b) to demonstrate correct interaction between valve electronics and power circuits of the
valves.
6.2 Test object
The tests may be performed on either the complete valve or on valve sections. The choice
depends mainly upon the valve design and the test facilities available. For switch type
converter valves, the tests specified in 6.2 are valid for valve sections containing five or more
– 16 – IEC 62927:2017 © IEC 2017
s
...
IEC 62927 ®
Edition 1.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
Valves de convertisseur source de tension (VSC) pour compensateur synchrone
statique (STATCOM) – Essais électriques
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IEC 62927 ®
Edition 1.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
Valves de convertisseur source de tension (VSC) pour compensateur synchrone
statique (STATCOM) – Essais électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.200; 29.240.99 ISBN 978-2-8322-5415-8
– 2 – IEC 62927:2017 © IEC 2017
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 Insulation co-ordination terms . 7
3.2 Power semiconductor terms . 8
3.3 Operating states of converter . 8
3.4 STATCOM construction terms . 9
3.5 Valve structure terms . 10
4 General requirements . 11
4.1 Guidelines for the performance of type tests . 11
4.1.1 General . 11
4.1.2 Dielectric tests . 11
4.1.3 Operational tests . 11
4.1.4 Electromagnetic interference tests . 11
4.1.5 Evidence in lieu . 11
4.1.6 Test object . 12
4.1.7 Test procedure . 12
4.1.8 Ambient temperature for testing . 12
4.1.9 Frequency for testing . 12
4.1.10 Conditions to be considered in determination of type test parameters . 12
4.1.11 Test reports . 12
4.2 Atmospheric correction factor . 12
4.3 Treatment of redundancy . 13
4.3.1 Operational tests . 13
4.3.2 Dielectric tests . 13
4.4 Permissible component failures during type testing . 14
5 List of tests . 14
6 Operational tests . 15
6.1 Purpose of tests . 15
6.2 Test object . 15
6.3 Test circuit . 16
6.4 Maximum continuous operating duty test . 16
6.5 Maximum temporary overload operating duty test . 17
6.6 Minimum start voltage test . 17
7 Dielectric tests on valve support . 18
7.1 Purpose of tests . 18
7.2 Test object . 18
7.3 Test requirements . 18
7.3.1 Valve support DC voltage test. 18
7.3.2 Valve support AC voltage test . 19
7.3.3 Valve support lightning impulse test . 20
8 Dielectric tests on multiple valve unit (MVU) . 20
8.1 General . 20
8.2 Purpose of tests . 20
8.3 Test object . 20
8.4 Test requirements . 20
8.4.1 MVU AC voltage test . 20
8.4.2 MVU DC voltage test . 21
8.4.3 MVU lightning impulse test . 21
9 Dielectric tests between valve terminals . 21
9.1 Purpose of the test . 21
9.2 Test object . 22
9.3 Test methods . 22
9.3.1 General . 22
9.3.2 Method 1 . 22
9.3.3 Method 2 . 23
9.4 Test requirements . 23
9.4.1 Valve AC voltage or AC-DC voltage test . 23
9.4.2 Valve switching impulse test . 25
10 IGBT overcurrent turn-off test . 26
10.1 Purpose of test . 26
10.2 Test object . 26
10.3 Test requirements . 26
11 Tests for valve insensitivity to electromagnetic disturbance . 27
11.1 Purpose of tests . 27
11.2 Test object . 27
11.3 Test requirements . 27
11.3.1 General . 27
11.3.2 Approach 1 . 27
11.3.3 Approach 2 . 28
11.3.4 Acceptance criteria . 28
12 Short-circuit current test (optional). 28
12.1 Purpose of tests . 28
12.2 Test object . 28
12.3 Test requirements . 28
13 Production tests. 29
13.1 General . 29
13.2 Purpose of tests . 29
13.3 Test object . 29
13.4 Test requirements . 29
13.5 Production test objectives . 30
13.5.1 Visual inspection . 30
13.5.2 Connection check . 30
13.5.3 Voltage-grading circuit check . 30
13.5.4 Control, protection and monitoring circuit checks . 30
13.5.5 Voltage withstand check . 30
13.5.6 Turn-on/turn-off check . 30
13.5.7 Pressure test . 30
14 Presentation of type test results . 30
Annex A (informative) Overview of STATCOM valves . 31
A.1 General . 31
A.2 STATCOM applications and operating limits . 31
A.3 Overview of STATCOM valve types. 32
– 4 – IEC 62927:2017 © IEC 2017
A.4 STATCOMs based on switch type valve . 32
A.4.1 General . 32
A.4.2 Two-level converter . 33
A.4.3 Three-level converters . 33
A.4.4 Multi-level converters. 34
A.5 STATCOMs based on controllable voltage source type valve . 35
A.6 Valve switching principles . 36
Annex B (informative) Valve component fault tolerance. 38
Bibliography . 39
Figure A.1 – STATCOM U-I characteristics . 32
Figure A.2 – Two-level converter . 33
Figure A.3 – Three-level NPC converter . 34
Figure A.4 – Three-level flying capacitor converter . 34
Figure A.5 – Modular multilevel converter . 35
Figure A.6 – Single-phase full-bridge converter. 36
Figure A.7 – Two-level converter output voltage . 36
Figure A.8 – Output voltage shape of three-level converter and modular multi-level
converter . 37
Table 1 – Minimum number of valve levels to be tested as a function of the number of
valve levels per valve . 12
Table 2 – Valve level faults permitted during type tests . 14
Table 3 – List of type tests . 15
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62927 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 bilingual version (2018-02) corresponds to the monolingual English version, published in
2017-07.
The text of this International Standard is based on the following documents:
CDV Report on voting
22F/412/CDV 22F/431A/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
– 6 – IEC 62927:2017 © IEC 2017
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
1 Scope
This document applies to self-commutated valves, for use in voltage sourced converter (VSC)
for static synchronous compensator (STATCOM). It is restricted to electrical type and
production tests.
The tests specified in this document are based on air insulated valves. For other types of
valves, the test requirements and acceptance criteria are agreed between the purchaser and
the supplier.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60060 (all parts), High-voltage test techniques
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1:2006, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power transmission
– Part 1: Electrical testing
IEC 62501, Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Insulation co-ordination terms
3.1.1
test withstand voltage
value of a test voltage of standard waveshape at which a new valve, with unimpaired integrity,
does not show any disruptive discharge and meets all other acceptance criteria specified for
the particular test, when subjected to a specified number of applications or a specified
duration of the test voltage, under specified conditions
– 8 – IEC 62927:2017 © IEC 2017
3.1.2
internal insulation
air external to the components and insulating materials of the valve, but contained within the
profile of the valve or multiple valve unit
3.1.3
external insulation
air between the external surface of the valve or multiple valve unit and its surroundings
3.2 Power semiconductor terms
3.2.1
turn-off semiconductor device
controllable semiconductor device which may be turned on and off by a control signal, for
example an IGBT
Note 1 to entry: There are several types of turn-off semiconductor devices, for example IGBT, IGCT and GTO,
which can be used in voltage sourced converters for STATCOM. For convenience, the term IGBT is used
throughout this document to refer to the main, controllable turn-off, semiconductor device. However, this document
is equally applicable to other types of controllable semiconductor switch device.
3.2.2
gate turn-off thyristor
GTO thyristor
turn-off semiconductor device which can be turned on and off by its gate lead
Note 1 to entry: A GTO thyristor is a special type of thyristor, which is a high-power semiconductor device.
Note 2 to entry: Gate commutated thyristor (GCT) and integrated gate commutated thyristor (IGCT) are special
types of GTO thyristor.
3.2.3
insulated gate bipolar transistor
IGBT
transistor provided for power switching having a conduction channel and a PN junction and in
which the current flowing through the channel and the junction is controlled by an electric field
resulting from a voltage applied between the gate and emitter terminals
3.2.4
free-wheeling diode
FWD
power semiconductor device with diode characteristic connected to an insulated gate bipolar
transistor (IGBT) in inverse parallel
Note 1 to entry: An FWD has two terminals: an anode (A) and a cathode (K).
Note 2 to entry: The current through FWDs is in the opposite direction to the IGBT current.
Note 3 to entry: Concepts of "inverse parallel" and "anti-parallel" are identical.
3.2.5
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.3 Operating states of converter
3.3.1
blocking state
condition of the converter, in which a turn-off signal is applied continuously to all IGBTs of the
converter
3.3.2
de-blocked state
condition of the converter, in which turn-on and turn-off signals are applied repetitively to
IGBTs of the converter
3.3.3
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
3.3.4
voltage step level
voltage step caused by switching of a valve or part of a valve during the de-blocked state of
the converter
Note 1 to entry: For a voltage source type valve, one half bridge cell corresponds to one voltage step level and a
full bridge cell has two voltage step levels.
3.4 STATCOM construction terms
3.4.1
STATCOM
shunt connected reactive compensation equipment which is capable of generating and/or
absorbing reactive power, whose capacitive or inductive output current can be controlled
independently of the AC system voltage
Note 1 to entry: Previous alternative terms for the STATCOM have included static var generator (SVG), advanced
static var compensator (ASVC) and static synchronous condenser (STATCON).
3.4.2
STATCOM valve
electrically and mechanically combined assembly of IGBT levels, complete with all
connections, auxiliary components and mechanical structures, which can be connected in
series with each phase of reactor of a STATCOM
Note 1 to entry: Depending 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. For controllable voltage source type converter, the
STATCOM controllable voltage source type valve is a complete controllable voltage source assembly, which is
generally connected between two AC phases. For switch type converter, the STATCOM switch type valve is an
arrangement of IGBTs connected in series and arranged to be switched simultaneously as a single function unit
between one AC phase and one DC terminal of the DC capacitor energy storage.
Note 2 to entry: For convenience, the term "STATCOM valve" is shortened as "valve" in this document.
3.4.3
diode valve
semiconductor valve containing only diodes as the main semiconductor devices, which might
be used in some STATCOM topologies
3.4.4
submodule
part of a valve comprising controllable switches and diodes connected in a half bridge or full
bridge arrangement, together with their immediate auxiliaries, storage capacitor, if any, where
each controllable switch consists of one or more switched valve device(s) connected in series
Note 1 to entry: This definition is only applicable for converters of controllable voltage source type.
3.4.5
switch type valve
arrangement of IGBT-diode pairs connected in series and arranged to be switched
simultaneously as a single function unit
– 10 – IEC 62927:2017 © IEC 2017
3.4.6
controllable voltage source type valve
complete controllable voltage source assembly, which is generally connected between AC
phases or between one AC terminal and one DC terminal
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve (see 3.4.5, 3.4.6) consists of a number of MMC
building blocks (see 3.4.9) connected in series
3.4.8
cascaded two-level converter
CTL
modular multi-level converter in which each switch position consists of more than one
IGBT-diode pair connected in series
3.4.9
MMC building block
self-contained, two-terminal controllable voltage source together with DC capacitor(s) and
immediate auxiliaries, forming part of a MMC
3.4.10
STATCOM valve level
the smallest indivisible functional unit of valve
Note 1 to entry: For any valve in which switch devices are connected in series and operated simultaneously, one
valve level is one IGBT including its auxiliaries. For modular multilevel converter (MMC) type without IGBT
connected in series, one valve level is one submodule (cell) together with its auxiliaries.
3.4.11
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.12
redundant valve levels
the maximum number of series connected valve levels or diode valve levels in a valve that
may be short-circuited externally or internally 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 1 to entry: In valve designs 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.
3.5 Valve structure terms
3.5.1
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.5.2
valve support
part of the valve which mechanically supports and electrically insulates the active part of the
valve from earth
3.5.3
multiple valve unit
MVU
mechanical arrangement of two or more valves sharing a common valve support, where
applicable
3.5.4
valve section
electrical assembly defined for test purposes, comprising a number of valve levels and other
components, which exhibits pro-rated electrical properties of a complete valve
3.5.5
valve base electronics
electronic unit, at earth potential, which is the interface between the converter control system
and the STATCOM valves
4 General requirements
4.1 Guidelines for the performance of type tests
4.1.1 General
The tests described apply to the valve (or valve sections), the valve structure and those parts
of the coolant distribution system and firing and monitoring circuits which are contained within
the valve structure (internal insulation) or connected between the valve structure and earth
(external insulation). Other equipment, such as valve control and protection and valve base
electronics, can be essential for demonstrating the correct function of the valve during the
tests but are not in themselves the subject of the tests.
4.1.2 Dielectric tests
The purpose of these tests is to verify the valve design for voltage stresses under normal and
abnormal repetitive conditions as well as under transient conditions.
In the interest of standardization with other equipment, lightning impulse tests between valve
terminals and earth and between phases of a multiple valve unit (MVU) are included. For tests
between valve terminals, the only impulse test specified is a switching impulse.
4.1.3 Operational tests
The purpose of these tests is to verify the valve design for combined voltage and current
stresses under normal and abnormal repetitive conditions as well as under transient fault
conditions.
4.1.4 Electromagnetic interference tests
The principal objective of these tests is to demonstrate the immunity of the valve to
electromagnetic interference from within the valve and from outside the valve.
4.1.5 Evidence in lieu
Each design of valve shall be subjected to the type tests specified in this document. If the
valve is demonstrably similar to one previously tested, the supplier may, in lieu of performing
a type test, submit a test report of a previous type test for consideration by the purchaser.
This should be accompanied by a separate report detailing the differences in the design and
demonstrating how the referenced type test satisfies the test objectives for the proposed
design.
– 12 – IEC 62927:2017 © IEC 2017
4.1.6 Test object
4.1.6 does not apply to tests on the valve support and multiple valve units. The test object for
those tests may be a representative separate object including representation of the adjacent
parts of the valve, or may form part of the assembly used for single valve or multiple valve
unit tests.
a) Type tests may be performed either on a complete valve or, in certain circumstances, on
valve sections, as indicated in Table 3.
b) The minimum number of valve levels to be tested, depending on the valve levels in a
single valve, is as shown in Table 1.
Table 1 – Minimum number of valve levels to be tested as a function
of the number of valve levels per valve
Number of valve levels per valve Total number of valve levels to be tested
1 to 10 Number of valve levels in one valve
11 to 50 10 levels
20% of valve levels in one valve
≥ 51
c) Generally, the same valve sections are recommended to be used for all type tests.
However, with the agreement of the purchaser and supplier, different tests may be
performed on different valve sections in parallel, in order to speed up the programme for
executing the tests.
d) Prior to commencement of type tests, the valve, valve sections and/or the components of
them should be demonstrated to have withstood the production tests to ensure proper
manufacture.
4.1.7 Test procedure
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.8 Ambient temperature for testing
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.9 Frequency for testing
AC dielectric tests can be performed at either 50 Hz or 60 Hz. For operational tests, specific
requirements regarding the frequency for testing are given in the relevant clauses.
4.1.10 Conditions to be considered in determination of type test parameters
Type test parameters should be determined based on the worst operating and fault conditions
to which the valve can be subjected, according to system studies.
4.1.11 Test reports
At the completion of the type tests, the supplier shall provide type test reports in accordance
with Clause 14.
4.2 Atmospheric correction factor
When specified in the relevant clause, atmospheric correction shall be applied to the test
voltages in accordance with IEC 60060-1. The reference conditions to which correction shall
be made are the following.
– Pressure
• If the insulation coordination of the tested part of the valve is based on standard rated
withstand voltages according to IEC 60071-1, correction factors for site conditions are
only applied for altitudes exceeding 1000 m. Hence, if the altitude of the site a at
s
which the equipment will be installed is ≤ 1 000 m, then the standard atmospheric air
pressure (b = 101,3 kPa) shall be used with no correction for altitude. If a > 1 000 m,
0 s
then the standard procedure according to IEC 60060-1 is used except that the
is replaced by the atmospheric pressure
reference atmospheric pressure b
corresponding to an altitude of 1000 m (b ).
1 000 m
• If the insulation coordination of the tested part of the valve is not based on standard
rated withstand voltages according to IEC 60071-1, then the correction factor for site
conditions follows the standard procedure according to IEC 60060-1 with the reference
atmospheric pressure b (b = 101,3 kPa).
0 0
– Temperature: design maximum valve hall air temperature (°C).
– Humidity: design minimum valve hall absolute humidity (g/m ).
Realistic worst case combinations of temperature and humidity which can occur in practice
shall be used for atmospheric correction.
The values to be used shall be specified by the supplier.
4.3 Treatment of redundancy
4.3.1 Operational tests
For operational tests, redundant valve levels shall not be short-circuited. The test voltages
used shall be adjusted by means of a scaling factor k :
n
N
tut
k =
n
N − N
t r
where
N is the number of series valve levels in the test object;
tut
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
4.3.2 Dielectric tests
For all dielectric tests between valve terminals, the redundant valve levels shall be short-
circuited. The location of valve levels to be short-circuited shall be agreed by the purchaser
and supplier.
NOTE Depending on the design, limitations can be imposed upon the distribution of short-circuited valve levels.
For example, there can be an upper limit to the number of short-circuited valve levels in one valve section.
For all dielectric tests on valve section, the test voltages used shall be adjusted by means of a
scaling factor k :
o
N
tu
k =
o
Ν −Ν
t r
where
N is the number of series valve levels not short circuit connected in the test object;
tu
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
– 14 – IEC 62927:2017 © IEC 2017
4.4 Permissible component failures during type testing
Experience in semiconductor application shows that, even with the most careful design of
valves, it is not possible to avoid occasional random failures of valve level components during
service operation. Even though these failures may be stress-related, they are considered
random to the extent that the cause of failure or the relationship between failure rate and
stress cannot be predicted or is not amenable to precise quantitative definition. Type tests
subject valves or valve sections, within a short time, to multiple stresses that generally
correspond to the worst stresses that can be experienced by the equipment not more than a
few times during the life of the valve. Considering the above, the criteria for successful type
testing set out below therefore permit a small number of valve levels to fail during type
testing, providing that the failures are rare and do not show any pattern that is indicative of
inadequate design and providing the failed valve level permits the rest of the valve or valve
section to continue operating without degraded performance.
The valves or valve sections shall be checked before each test, after any preliminary
calibration tests, and again after each type test to determine whether or not any insulated
gate bipolar transistors (IGBTs) or auxiliary components have failed during the test. Failed
IGBTs or auxiliary components found at the end of a type test shall be remedied before
further testing o
...
IEC 62927 ®
Edition 1.1 2023-05
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
Valves de convertisseur source de tension (VSC) pour compensateur synchrone
statique (STATCOM) – Essais électriques
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IEC 62927 ®
Edition 1.1 2023-05
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
Valves de convertisseur source de tension (VSC) pour compensateur synchrone
statique (STATCOM) – Essais électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.200; 29.240.99 ISBN 978-2-8322-7025-7
IEC 62927 ®
Edition 1.1 2023-05
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Voltage sourced converter (VSC) valves for static synchronous compensator
(STATCOM) – Electrical testing
Valves de convertisseur source de tension (VSC) pour compensateur synchrone
statique (STATCOM) – Essais électriques
– 2 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 Insulation co-ordination terms . 7
3.2 Power semiconductor terms . 8
3.3 Operating states of converter . 8
3.4 STATCOM construction terms . 9
3.5 Valve structure terms . 10
4 General requirements . 11
4.1 Guidelines for the performance of type tests . 11
4.1.1 General . 11
4.1.2 Dielectric tests . 11
4.1.3 Operational tests . 11
4.1.4 Electromagnetic interference tests . 11
4.1.5 Evidence in lieu . 11
4.1.6 Test object . 12
4.1.7 Test procedure . 12
4.1.8 Ambient temperature for testing . 12
4.1.9 Frequency for testing . 12
4.1.10 Conditions to be considered in determination of type test parameters . 12
4.1.11 Test reports . 12
4.2 Atmospheric correction factor . 13
4.3 Treatment of redundancy . 13
4.3.1 Operational tests . 13
4.3.2 Dielectric tests . 13
4.4 Permissible component failures during type testing . 14
5 List of tests . 14
6 Operational tests . 15
6.1 Purpose of tests . 15
6.2 Test object . 15
6.3 Test circuit . 16
6.4 Maximum continuous operating duty test . 16
6.5 Maximum temporary overload operating duty test . 17
6.6 Minimum start voltage test . 17
7 Dielectric tests on valve support . 18
7.1 Purpose of tests . 18
7.2 Test object . 18
7.3 Test requirements . 18
7.3.1 Valve support DC voltage test. 18
7.3.2 Valve support AC voltage test . 19
7.3.3 Valve support lightning impulse test . 20
8 Dielectric tests on multiple valve unit (MVU) . 20
8.1 General . 20
8.2 Purpose of tests . 20
8.3 Test object . 20
© IEC 2023
8.4 Test requirements . 21
8.4.1 MVU AC voltage test . 21
8.4.2 MVU DC voltage test . 21
8.4.3 MVU lightning impulse test . 22
9 Dielectric tests between valve terminals . 22
9.1 Purpose of the test . 22
9.2 Test object . 22
9.3 Test methods . 23
9.3.1 General . 23
9.3.2 Method 1 . 23
9.3.3 Method 2 . 23
9.4 Test requirements . 23
9.4.1 Valve AC voltage or AC-DC voltage test . 23
9.4.2 Valve switching impulse test . 26
10 IGBT overcurrent turn-off test . 27
10.1 Purpose of test . 27
10.2 Test object . 27
10.3 Test requirements . 27
11 Tests for valve insensitivity to electromagnetic disturbance . 27
11.1 Purpose of tests . 27
11.2 Test object . 28
11.3 Test requirements . 28
11.3.1 General . 28
11.3.2 Approach 1 . 28
11.3.3 Approach 2 . 28
11.3.4 Acceptance criteria . 29
12 Short-circuit current test (optional). 29
12.1 Purpose of tests . 29
12.2 Test object . 29
12.3 Test requirements . 29
13 Production tests. 30
13.1 General . 30
13.2 Purpose of tests . 30
13.3 Test object . 30
13.4 Test requirements . 30
13.5 Production test objectives . 30
13.5.1 Visual inspection . 30
13.5.2 Connection check . 31
13.5.3 Voltage-grading circuit check . 31
13.5.4 Control, protection and monitoring circuit checks . 31
13.5.5 Voltage withstand check . 31
13.5.6 Turn-on/turn-off check . 31
13.5.7 Pressure test . 31
14 Presentation of type test results . 31
Annex A (informative) Overview of STATCOM valves . 32
A.1 General . 32
A.2 STATCOM applications and operating limits . 32
A.3 Overview of STATCOM valve types. 33
– 4 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
A.4 STATCOMs based on switch type valve . 33
A.4.1 General . 33
A.4.2 Two-level converter . 34
A.4.3 Three-level converters . 34
A.4.4 Multi-level converters. 35
A.5 STATCOMs based on controllable voltage source type valve . 36
A.6 Valve switching principles . 37
Annex B (informative) Valve component fault tolerance. 39
Bibliography . 40
Figure A.1 – STATCOM U-I characteristics . 33
Figure A.2 – Two-level converter . 34
Figure A.3 – Three-level NPC converter . 35
Figure A.4 – Three-level flying capacitor converter . 35
Figure A.5 – Modular multilevel converter . 36
Figure A.6 – Single-phase full-bridge converter. 37
Figure A.7 – Two-level converter output voltage . 37
Figure A.8 – Output voltage shape of three-level converter and modular multi-level
converter . 38
Table 1 – Minimum number of valve levels to be tested as a function of the number of
valve levels per valve . 12
Table 2 – Valve level faults permitted during type tests . 14
Table 3 – List of type tests . 15
© IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 62927 edition 1.1 contains the first edition (2017-07) [documents 22F/412/CDV and
22F/431A/RVC] and its amendment 1 (2023-05) [documents 22F/699/CDV and
22F/721/RVC].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
– 6 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
International Standard IEC 62927 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 document 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 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.
© IEC 2023
VOLTAGE SOURCED CONVERTER (VSC) VALVES FOR STATIC
SYNCHRONOUS COMPENSATOR (STATCOM) –
ELECTRICAL TESTING
1 Scope
This document applies to self-commutated valves, for use in voltage sourced converter (VSC)
for static synchronous compensator (STATCOM). It is restricted to electrical type and
production tests.
The tests specified in this document are based on air insulated valves. For other types of
valves, the test requirements and acceptance criteria are agreed between the purchaser and
the supplier.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60060 (all parts), High-voltage test techniques
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1:20062019, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power transmission
– Part 1: Electrical testing
IEC 62501, Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Insulation co-ordination terms
3.1.1
test withstand voltage
value of a test voltage of standard waveshape at which a new valve, with unimpaired integrity,
does not show any disruptive discharge and meets all other acceptance criteria specified for
the particular test, when subjected to a specified number of applications or a specified
duration of the test voltage, under specified conditions
– 8 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
3.1.2
internal insulation
air external to the components and insulating materials of the valve, but contained within the
profile of the valve or multiple valve unit
3.1.3
external insulation
air between the external surface of the valve or multiple valve unit and its surroundings
3.2 Power semiconductor terms
3.2.1
turn-off semiconductor device
controllable semiconductor device which may be turned on and off by a control signal, for
example an IGBT
Note 1 to entry: There are several types of turn-off semiconductor devices, for example IGBT, IGCT and GTO,
which can be used in voltage sourced converters for STATCOM. For convenience, the term IGBT is used
throughout this document to refer to the main, controllable turn-off, semiconductor device. However, this document
is equally applicable to other types of controllable semiconductor switch device.
3.2.2
gate turn-off thyristor
GTO thyristor
turn-off semiconductor device which can be turned on and off by its gate lead
Note 1 to entry: A GTO thyristor is a special type of thyristor, which is a high-power semiconductor device.
Note 2 to entry: Gate commutated thyristor (GCT) and integrated gate commutated thyristor (IGCT) are special
types of GTO thyristor.
3.2.3
insulated gate bipolar transistor
IGBT
transistor provided for power switching having a conduction channel and a PN junction and in
which the current flowing through the channel and the junction is controlled by an electric field
resulting from a voltage applied between the gate and emitter terminals
3.2.4
free-wheeling diode
FWD
power semiconductor device with diode characteristic connected to an insulated gate bipolar
transistor (IGBT) in inverse parallel
Note 1 to entry: An FWD has two terminals: an anode (A) and a cathode (K).
Note 2 to entry: The current through FWDs is in the opposite direction to the IGBT current.
Note 3 to entry: Concepts of "inverse parallel" and "anti-parallel" are identical.
3.2.5
IGBT-diode pair
arrangement of IGBT and FWD connected in inverse parallel
3.3 Operating states of converter
3.3.1
blocking state
condition of the converter, in which a turn-off signal is applied continuously to all IGBTs of the
converter
© IEC 2023
3.3.2
de-blocked state
condition of the converter, in which turn-on and turn-off signals are applied repetitively to
IGBTs of the converter
3.3.3
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
3.3.4
voltage step level
voltage step caused by switching of a valve or part of a valve during the de-blocked state of
the converter
Note 1 to entry: For a voltage source type valve, one half bridge cell corresponds to one voltage step level and a
full bridge cell has two voltage step levels.
3.4 STATCOM construction terms
3.4.1
STATCOM
shunt connected reactive compensation equipment which is capable of generating and/or
absorbing reactive power, whose capacitive or inductive output current can be controlled
independently of the AC system voltage
Note 1 to entry: Previous alternative terms for the STATCOM have included static var generator (SVG), advanced
static var compensator (ASVC) and static synchronous condenser (STATCON).
3.4.2
STATCOM valve
electrically and mechanically combined assembly of IGBT levels, complete with all
connections, auxiliary components and mechanical structures, which can be connected in
series with each phase of reactor of a STATCOM
Note 1 to entry: Depending 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. For controllable voltage source type converter, the
STATCOM controllable voltage source type valve is a complete controllable voltage source assembly, which is
generally connected between two AC phases. For switch type converter, the STATCOM switch type valve is an
arrangement of IGBTs connected in series and arranged to be switched simultaneously as a single function unit
between one AC phase and one DC terminal of the DC capacitor energy storage.
Note 2 to entry: For convenience, the term "STATCOM valve" is shortened as "valve" in this document.
3.4.3
diode valve
semiconductor valve containing only diodes as the main semiconductor devices, which might
be used in some STATCOM topologies
3.4.4
submodule
part of a valve comprising controllable switches and diodes connected in a half bridge or full
bridge arrangement, together with their immediate auxiliaries, storage capacitor, if any, where
each controllable switch consists of one or more switched valve device(s) connected in series
Note 1 to entry: This definition is only applicable for converters of controllable voltage source type.
3.4.5
switch type valve
arrangement of IGBT-diode pairs connected in series and arranged to be switched
simultaneously as a single function unit
– 10 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
3.4.6
controllable voltage source type valve
complete controllable voltage source assembly, which is generally connected between AC
phases or between one AC terminal and one DC terminal
3.4.7
modular multi-level converter
MMC
multi-level converter in which each VSC valve (see 3.4.5, 3.4.6) consists of a number of MMC
building blocks (see 3.4.9) connected in series
3.4.8
cascaded two-level converter
CTL
modular multi-level converter in which each switch position consists of more than one
IGBT-diode pair connected in series
3.4.9
MMC building block
self-contained, two-terminal controllable voltage source together with DC capacitor(s) and
immediate auxiliaries, forming part of a MMC
3.4.10
STATCOM valve level
the smallest indivisible functional unit of valve
Note 1 to entry: For any valve in which switch devices are connected in series and operated simultaneously, one
valve level is one IGBT including its auxiliaries. For modular multilevel converter (MMC) type without IGBT
connected in series, one valve level is one submodule (cell) together with its auxiliaries.
3.4.11
diode valve level
part of a diode valve composed of a diode and associated circuits and components, if any
3.4.12
redundant valve levels
the maximum number of series connected valve levels or diode valve levels in a valve that
may be short-circuited externally or internally 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 1 to entry: In valve designs 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.
3.5 Valve structure terms
3.5.1
valve structure
physical structure holding the levels of a valve which is insulated to the appropriate voltage
above earth potential
3.5.2
valve support
part of the valve which mechanically supports and electrically insulates the active part of the
valve from earth
© IEC 2023
3.5.3
multiple valve unit
MVU
mechanical arrangement of two or more valves sharing a common valve support, where
applicable
3.5.4
valve section
electrical assembly defined for test purposes, comprising a number of valve levels and other
components, which exhibits pro-rated electrical properties of a complete valve
3.5.5
valve base electronics
electronic unit, at earth potential, which is the interface between the converter control system
and the STATCOM valves
4 General requirements
4.1 Guidelines for the performance of type tests
4.1.1 General
The tests described apply to the valve (or valve sections), the valve structure and those parts
of the coolant distribution system and firing and monitoring circuits which are contained within
the valve structure (internal insulation) or connected between the valve structure and earth
(external insulation). Other equipment, such as valve control and protection and valve base
electronics, can be essential for demonstrating the correct function of the valve during the
tests but are not in themselves the subject of the tests.
4.1.2 Dielectric tests
The purpose of these tests is to verify the valve design for voltage stresses under normal and
abnormal repetitive conditions as well as under transient conditions.
In the interest of standardization with other equipment, lightning impulse tests between valve
terminals and earth and between phases of a multiple valve unit (MVU) are included. For tests
between valve terminals, the only impulse test specified is a switching impulse.
4.1.3 Operational tests
The purpose of these tests is to verify the valve design for combined voltage and current
stresses under normal and abnormal repetitive conditions as well as under transient fault
conditions.
4.1.4 Electromagnetic interference tests
The principal objective of these tests is to demonstrate the immunity of the valve to
electromagnetic interference from within the valve and from outside the valve.
4.1.5 Evidence in lieu
Each design of valve shall be subjected to the type tests specified in this document. If the
valve is demonstrably similar to one previously tested, the supplier may, in lieu of performing
a type test or individual parts of it, submit a test report of a previous type test for
consideration by the purchaser. This should be accompanied by a separate report detailing
the differences in the design and demonstrating how the referenced type test satisfies the test
objectives for the proposed design.
– 12 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
4.1.6 Test object
4.1.6 does not apply to tests on the valve support and multiple valve units. The test object for
those tests may be a representative separate object including representation of the adjacent
parts of the valve, or may form part of the assembly used for single valve or multiple valve
unit tests.
a) Type tests may be performed either on a complete valve or, in certain circumstances, on
valve sections, as indicated in Table 3.
b) The minimum number of valve levels to be tested, depending on the valve levels in a
single valve, is as shown in Table 1.
Table 1 – Minimum number of valve levels to be tested as a function
of the number of valve levels per valve
Number of valve levels per valve, including Total number of valve levels to be tested
redundant levels
1 to 10 Number of valve levels in one valve
11 to 50 10 valve levels
20% of valve levels in one valve
≥ 51
c) Generally, the same valve sections are recommended to be used for all type tests.
However, with the agreement of the purchaser and supplier, different tests may be
performed on different valve sections in parallel, in order to speed up the programme for
executing the tests.
d) Prior to commencement of type tests, the valve, valve sections and/or the components of
them should shall be demonstrated to have withstood the production tests to ensure
proper manufacture.
Subclause 4.1.6 does not apply to tests on the valve supporting structure and multiple valve
unit. The test object for those tests is defined in 7.2 and 8.3.
4.1.7 Test procedure
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.8 Ambient temperature for testing
The tests shall be performed in accordance with IEC 60060 (all parts), where applicable.
4.1.9 Frequency for testing
AC dielectric tests can be performed at either 50 Hz or 60 Hz. For operational tests, specific
requirements regarding the frequency for testing are given in the relevant clauses.
4.1.10 Conditions to be considered in determination of type test parameters
Type test parameters should shall be determined based on the worst operating and fault
conditions to which the valve can be subjected, according to system studies.
4.1.11 Test reports
At the completion of the type tests, the supplier shall provide type test reports in accordance
with Clause 14.
© IEC 2023
4.2 Atmospheric correction factor
When specified in the relevant clause, atmospheric correction shall be applied to the test
voltages in accordance with IEC 60060-1. The reference conditions to which correction shall
be made are the following.
– Pressure
• If the insulation coordination of the tested part of the valve is based on standard rated
withstand voltages according to IEC 60071-1, correction factors for site conditions are
only applied for altitudes exceeding 1000 m. Hence, if the altitude of the site a at
s
which the equipment will be installed is ≤ 1 000 m, then the standard atmospheric air
pressure (b = 101,3 kPa) shall be used with no correction for altitude. If a > 1 000 m,
0 s
then the standard procedure according to IEC 60060-1 is used except that the
reference atmospheric pressure b is replaced by the atmospheric pressure
corresponding to an altitude of 1000 m (b ).
1 000 m
• If the insulation coordination of the tested part of the valve is not based on standard
rated withstand voltages according to IEC 60071-1, then the correction factor for site
conditions follows the standard procedure according to IEC 60060-1 with the reference
atmospheric pressure b (b = 101,3 kPa).
0 0
– Temperature: design maximum valve hall air temperature (°C).
– Humidity: design minimum valve hall absolute humidity (g/m ).
Realistic worst case combinations of temperature and humidity which can occur in practice
shall be used for atmospheric correction.
The values to be used shall be specified by the supplier.
4.3 Treatment of redundancy
4.3.1 Operational tests
For operational tests, redundant valve levels shall not be short-circuited. The test voltages
used shall be adjusted by means of a scaling factor k :
n
N
tut
k =
n
N − N
t r
where
N is the number of series valve levels in the test object;
tut
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
4.3.2 Dielectric tests
For all dielectric tests between valve terminals, the redundant valve levels shall be short-
circuited. The location of valve levels to be short-circuited shall be agreed by the purchaser
and supplier.
NOTE Depending on the design, limitations can be imposed upon the distribution of short-circuited valve levels.
For example, there can be an upper limit to the number of short-circuited valve levels in one valve section.
For all dielectric tests on valve section, the test voltages used shall be adjusted by means of a
scaling factor k :
o
N
tu
k =
o
Ν −Ν
t r
– 14 – IEC 62927:2017+AMD1:2023 CSV
© IEC 2023
where
N is the number of series valve levels not short circuit connected in the test object;
tu
N is the total number of series valve levels in the valve;
t
N is the total number of redundant series valve levels in the valve.
r
4.4 Permissible component failures during type testing
Experience in semiconductor application shows that, even with the most careful design of
valves, it is not possible to avoid occasional random failures of valve level components during
service operation. Even though these failures may be stress-related, they are considered
random to the extent that the cause of failure or the relationship between failure rate and
stress cannot be predicted or is not amenable to precise quantitative definition. Type tests
subject valves or valve sections, within a short time, to multiple stresses that generally
correspond to the worst stresses that can be experienced by the equipment not more than a
few times during the life of the valve. Considering the above, the criteria for successful type
testing set out below therefore permit a small number of valve levels to fail during type
testing, providing that the failures are rare and do not show any pattern that is indicative of
inadequate design and providing the failed valve level permits the rest of the valve or valve
section to continue operating without degraded performance.
The valves or valve sections shall be checked before each test, after any preliminary
calibrat
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