SIST EN 61975:2010

SLOVENSKI STANDARD
01-november-2010
Visokonapetostne enosmerne inštalacije (HVDC) - Sistemski preskusi (IEC
61975:2010)
High-voltage direct current (HVDC) installations - System tests (IEC 61975:2010)
Anlagen zur Hochspannungsgleichstromübertragung (HGÜ) - Systemprüfungen (IEC
61975:2010)
Installations en courant continu à haute tension (CCHT) - Essais système (CEI
61975:2010)
Ta slovenski standard je istoveten z: EN 61975:2010
ICS:
29.130.10 Visokonapetostne stikalne in High voltage switchgear and
krmilne naprave controlgear
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61975
NORME EUROPÉENNE
September 2010
EUROPÄISCHE NORM
ICS 29.130.10; 31.080.01
English version
High-voltage direct current (HVDC) installations -
System tests
(IEC 61975:2010)
Installations en courant continu  Anlagen zur
à haute tension (CCHT) - Hochspannungsgleichstromübertragung
Essais système (HGÜ) -
(CEI 61975:2010) Systemprüfungen
(IEC 61975:2010)
This European Standard was approved by CENELEC on 2010-09-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61975:2010 E
Foreword
The text of document 22F/221/FDIS, future edition 1 of IEC 61975, prepared by SC 22F, Power
electronics for electrical transmission and distribution systems, of IEC TC 22, Power electronic systems
and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 61975 on 2010-09-01.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2011-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2013-09-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61975:2010 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC/TR 60919-1 NOTE  Harmonized as CLC/TR 60919-1.
IEC 61000-4-3 NOTE  Harmonized as EN 61000-4-3.
IEC 61803 NOTE  Harmonized as EN 61803.
__________
- 3 - EN 61975:2010
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60633 1998 Terminology for high-voltage direct current EN 60633 1999
(HVDC) transmission
1)
IEC/TR 60919-2 2008 Performance of high-voltage direct current CLC/TR 60919-2 201X
(HVDC) systems with line-commutated
converters -
Part 2: Faults and switching
1)
At draft stage.
IEC 61975 ®
Edition 1.0 2010-07
INTERNATIONAL
STANDARD
High-voltage direct current (HVDC) installations – System tests

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.130.10; 31.080.01 ISBN 978-2-88912-100-7
– 2 – 61975 © IEC:2010(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references.7
3 Terms and definitions .7
3.1 Test classifications terms .7
3.2 Operation state terms .8
4 General .9
4.1 Purpose.9
4.2 Structure of the HVDC system .10
4.3 Structure of the control and protection system.11
4.4 Logical steps of system test.12
4.5 Structure of system test .13
4.6 Precondition for site test .13
5 Converter station test.16
5.1 General .16
5.2 Converter unit test .17
5.3 Energizing of reactive components.18
5.4 Changing the d.c. system configuration.19
5.5 Electromagnetic compatibility.20
5.6 Trip test.21
5.7 Open line test .22
5.8 Back-to-back test.24
5.9 Short circuit test .25
6 Transmission tests.26
6.1 Low power transmission tests .26
6.2 Operator control mode transfer .34
6.3 Changes of d.c. configuration .40
6.4 Main circuit equipment switching.43
6.5 Dynamic performance testing.47
6.6 AC and d.c. system staged faults .56
6.7 Loss of telecom, auxiliaries or redundant equipment .60
6.8 High power transmission tests .63
6.9 Acceptance tests .67
7 Trial operation .74
7.1 General .74
7.2 Purpose of test .74
7.3 Test precondition.74
7.4 Test procedure .74
7.5 Test acceptance criteria.75
8 System test plan and documentation .75
8.1 General .75
8.2 Plant documentation and operating manual.75
8.3 System study reports and technical specification.75
8.4 Inspection and test plan.76
8.5 System test program.76

61975 © IEC:2010(E) – 3 –
8.6 Test procedure for each test .77
8.7 Documentation of system test results.77
8.8 Deviation report .78
Bibliography .79

Figure 1 – Relation among five major aspects of system test .10
Figure 2 – Structure of the HVDC system .11
Figure 3 – Structure of the HVDC control and protection.11
Figure 4 – Structure of system test .15
Figure 5 – Sequence for low power transmission tests.28
Figure 6 – Step response test of current control at the rectifier .49
Figure 7 – Step response test of extinction angle control at the inverter .50
Figure 8 – Step response test of d.c. voltage control at the inverter .50
Figure 9 – Step response test of current control at the inverter .51
Figure 10 – Step response test of power control at the rectifier .51

– 4 – 61975 © IEC:2010(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE DIRECT CURRENT (HVDC) INSTALLATIONS –
SYSTEM TESTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61975 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 first version of IEC 61975 cancels and replaces IEC/PAS 61975 published jointly in 2004
by IEC and CIGRÉ. It constitutes a technical revision incorporating engineering experience.
The text of this standard is based on the following documents:
FDIS Report on voting
22F/221/FDIS 22F/227/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

61975 © IEC:2010(E) – 5 –
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.
A bilingual version may be issued at a later date.

– 6 – 61975 © IEC:2010(E)
INTRODUCTION
The standard is structured in eight clauses:
a) Clause 1 – Scope
b) Clause 2 – Normative references
c) Clause 3 – Definitions
d) Clause 4 – General
e) This clause addresses the purpose of this standard, the HVDC system structure, the
control and protection structure, the logical steps of commissioning, the structure of the
system test and that of the system commissioning standard.
f) Clause 5 – Converter station test
g) This clause addresses the commissioning of converter units and verifies the steady state
performance of units as well as switching tests.
h) Clause 6 – Power transmission tests
i) This clause concerns the commissioning of the transmission system, and verifies station
coordination, steady-state and dynamic performance, interference, as well as interaction
between the d.c. and a.c. systems.
j) Clause 7 – Trial operation
k) After completion of the system test, the period of trial operation is normally specified to
verify the normal transmission.
l) Clause 8 – System test plan and documentation
Clauses 5 to 7 comprise individual sections providing an introduction and covering objects,
preconditions and procedures and general acceptance criteria as well as detailed descriptions
of the individual tests.
61975 © IEC:2010(E) – 7 –
HIGH-VOLTAGE DIRECT CURRENT (HVDC) INSTALLATIONS –
SYSTEM TESTS
1 Scope
This International Standard applies to system tests for high-voltage direct current (HVDC)
installations which consist of a sending terminal and a receiving terminal, each connected to an
a.c. system.
The tests specified in this standard are based on bidirectional and bipolar high-voltage direct
current (HVDC) installations which consist of a sending terminal and a receiving terminal, each
connected to an a.c. system. The test requirements and acceptance criteria should be agreed
for back-to-back installations, while multi-terminal systems and voltage sourced converters are
not included in this standard. For monopolar HVDC installations, the standard applies except
for bipolar tests.
For the special functions or performances that are claimed by specific projects, some extra test
items not included in this standard should be added according to the technical specification
requirements.
This standard only serves as a guideline to system tests for high-voltage direct current (HVDC)
installations. The standard gives potential users guidance, regarding how to plan
commissioning activities. The tests described in the guide may not be applicable to all projects,
but represent a range of possible tests which should be considered.
Therefore, it is preferable that the project organization establishes the individual test program
based on this standard and in advance assigns responsibilities for various tasks/tests between
involved organisations (e.g. user, supplier, manufacturer, operator, purchaser etc.) for each
specific project.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For updated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60633:1998, Terminology for high-voltage direct current (HVDC) power transmission
IEC/TR 60919-2:2008, Performance of high-voltage direct current (HVDC) systems with line
commutated converters – Part 2: Faults and switching
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60633 as well as the
following terms and definitions apply.
3.1 Test classifications terms
3.1.1
station test
converter system test including items which verify the function of individual equipment of the
converter staton in energized state

– 8 – 61975 © IEC:2010(E)
3.1.2
system test
test verifying functions and performances of HVDC system as a whole as well as the interaction
with adjacent a.c. systems
3.1.3
transmission tests
test verifying functions and performances of HVDC system when transmitting power between
both terminals
NOTE It is also referred to as an “end to end test”.
3.2 Operation state terms
In the d.c. system, there are 5 defined states: earthed, stopped, standby, blocked, de-blocked.
3.2.1
earthed
state in which the pole or converter is isolated and earthed on the a.c. and d.c. sides and no
energizing of the pole or converter equipment is possible
NOTE The earthed state provides the necessary safety for carrying out maintenance work, and is the only one that
permits the pole or converter maintenance. In this state maintenance work is possible on the converter transformers,
the isolated and earthed part of the a.c. high voltage bus equipment, d.c. and valve hall installed equipment of this
pole or converter.
3.2.2
stopped/isolated
state in which the pole or converter is isolated from the a.c. and d.c. side, but all the earthing
switches are open
NOTE In this state the d.c. yard can be prepared for power transmission (earth electrode line, pole and d.c. line
connect).
3.2.3
standby
state which is to be used when the d.c. system is not being utilized but is ready for power
transmission
NOTE In this state the converter transformer is to be ready; tap-changer is automatically brought to the start
position, which ensures that the transformer will be energized with minimum voltage to minimize the inrush current.
The disconnector of the a.c. bay should be closed, but the circuit breakers in the feeding bay of the converter
transformer should be open. In this state the d.c. configuration can still be changed (earth electrode line, pole and
d.c. line connect).
3.2.4
blocked
state in which the pole is prepared to transmit power at a moment’s notice
NOTE The converter transformer is connected to the energized a.c. bus by means of closing of the respective
circuit breaker. The valve cooling system is ready for operation if the cooling water conductivity, flow and
temperature are within the specified limits. A defined d.c. configuration shall have been established. Further
changes are not possible in this state. The thyristor pre-check is carried out after the converter transformer has
been energized. The pre-check is considered as passed when in every valve the redundancy is not lost. To change
the blocked state, the states stopped, standby and de-blocked are selectable.
3.2.5
de-blocked
state representing the following two operating modes: power transmission and open line test
NOTE Power transmission is the normal operating mode. In the de-blocked status the pole transmits power in
normal operating mode if both terminals are in the deblocked stage and there is a voltage difference between the
terminals. A minimum number of a.c. filters should be available.

61975 © IEC:2010(E) – 9 –
3.2.6
off-site tests
tests which are performed before on-site testing
4 General
4.1 Purpose
System test completes the commissioning of an HVDC system.
The supplier can verify the suitability of the station equipment installed and the functional
completeness of the system. Moreover, adjustments and optimizations can be made.
It is shown for the user that the requirements and stipulations in the contract are met and that
there is correlation with studies and previous off-site tests.
For the user, the completion of system test marks the beginning of commercial operation of the
HVDC system.
When adapting the HVDC system to the connected a.c. systems, there may be various
constraints which require coordination within the economic schedules of the a.c. system
operators. System tests prove to the public that tolerable values of phenomena concerning the
public interest are not exceeded.
Five major aspects are subject to system tests:
a) HVDC station equipment and d.c. line/cable/bus including earth electrode, if any;
b) HVDC control and protection equipment and their settings;
c) environmental considerations;
d) a.c./d.c. system interaction;
e) system performance when jointly operated with a connected a.c. system.
The interrelation between these aspects is shown in Figure 1.

– 10 – 61975 © IEC:2010(E)
IEC  1895/10
Figure 1 – Relation among five major aspects of system test
Thorough and complete system test of the above components can be achieved with the tests
described in the standard.
Acceptance tests shall be defined between supplier and user in advance and may be
performed at an appropriate time during the test schedule.
System tests may affect more than the actual contract parties. Those parties shall be informed
in time.
The complexity and the diversified areas concerned during system test require thorough
planning and scheduling, cooperation of all involved parties, as well as complete and organized
documentation.
NOTE The suggested “Test Procedures” are recommendations and alternative test procedures may be used
subject to the agreement between supplier and user.
4.2 Structure of the HVDC system
From a functional point of view an HVDC system consists of a sending terminal and a receiving
terminal, each connected to an a.c. system. The two terminals have one or several converters
connected in series on the d.c. side and in parallel on the a.c. side. The terminals are
connected by a transmission line or cable or a short piece of busbar (back-to-back station).
Multi-terminal systems are not addressed in this standard.
The structure of the HVDC system is shown in Figure 2.

61975 © IEC:2010(E) – 11 –
IEC  1896/10
Figure 2 – Structure of the HVDC system
4.3 Structure of the control and protection system
Each of the converter units can be controlled individually. To make the system function
correctly as a power transmission system, the converter units should be controlled in a
coordinated way by a higher level of the control system. Coordinated controls and protection
are essential for the proper functioning of HVDC systems.
The structure of the HVDC control and protection is shown in Figure 3:

IEC  1897/10
Figure 3 – Structure of the HVDC control and protection

– 12 – 61975 © IEC:2010(E)
4.4 Logical steps of system test
To ensure proper functioning, the type test and functional performance test should be
conducted in factory in order to debug and test the control system before the site test.
In order to provide the power grid data and help to compile the system test plan, the off-line
digital simulation should be conducted before and during the simulation test, especially
analysis on the power flow, stability and overvoltage.
Considering the complexity of the HVDC system, all limiting design cases may be conducted on
the digital simulator in a similar way to those done on site.
Commissioning an HVDC system may affect more than the actual contract parties. The
complexity and the diversified areas concerned during system test require thorough planning
and scheduling, cooperation of all involved parties and complete and structured documentation.
Before a system test can begin on site, the following preconditions should be fulfilled
concerning subsystem tests, operator training and safety instructions, system test plan and test
procedures, and all necessary test equipment.
a) All subsystems should have been tested and commissioned, including a.c. filters and the
converter transformers with special attention to possible transformer or a.c. filter resonance
during energizing.
b) Operating personnel should be sufficiently trained.
c) Operating instructions for the station should be available.
d) Personnel, plant safety and security instructions should be available.
e) System test plan and documentation (Part 8) should be available and agreed upon.
f) AC/d.c. power profiles should have been agreed for each test.
g) Any a.c./d.c. system operating restrictions should have been identified.
h) Operator voice communications should be available
i) All necessary test equipment should have been calibrated and in service.
j) Procedures for the preparation and evaluation of test results should have been agreed
upon.
Site system tests should follow the structure of the HVDC system, starting from the smallest,
least complex operational unit, usually a 12-pulse converter, and shall end with the total system
in operation. The test sequence should be scheduled starting at the local level with simple tests
before involving additional locations and the transmission system and more complex tests.
After all preconditions are fulfilled, converter station tests should be conducted and begin from
the converter unit test, including energizing of a.c. filter and d.c. yard, electrical magnetic
interference，trip test, changing the d.c. system configuration, open line test, and so on.
The power transmission (also called end-to-end) test should start on a monopolar basis, with
bipolar operation, with full power being the final step.
Having the complete system running properly, performance of the steady state can be verified.
With normal operating ramp settings and automatic switching sequences in place, the effect of
a number of disturbances on the d.c. side of the system as well as in the a.c. systems may be
checked, and the transient and fault recovery performances may be verified.
Acceptance tests shall be defined between supplier and user in advance and may be
performed at an appropriate time during the test schedule.
The acceptance tests necessary to verify whether acceptance criteria have been met, may
have been performed wholly or in part during the commissioning period. To avoid unnecessary

61975 © IEC:2010(E) – 13 –
duplication of such tests, careful consideration should be given in advance as to when ac-
ceptance tests are carried out.
If acceptance tests are still outstanding or acceptance tests have to be repeated due to
modifications, they should be performed during the transmission testing, or following trial
operation, if appropriate.
Correct operation of the HVDC system over an extended period of time is checked during the
trial operation.
Complete and organized documentation of the system tests, which benefit both the supplier
and the user, shall form part of the project documentation and contain all necessary data
records, logs, etc, and if necessary a commentary and references.
After all the above HVDC system tests have been completed, all functions have been verified
and the HVDC system can be handed over to the users.
4.5 Structure of system test
The structure of the system test is shown in Figure 4.
4.6 Precondition for site test
4.6.1 Factory system test
This subclause describes site tests and the commissioning of the HVDC controls at the factory,
including real-time simulation test.
Subsequent to the routine test of the HVDC system control and protection equipment, it is
normal practice to check the function of the HVDC control and protection equipment in a
factory system test (= FST) prior to being shipped to site.
The factory system test provides the opportunity to set up the parameters of the control
systems and to obtain a proof on the performance of the equipment relative to the specified
requirements.
Performance of the protective functions of the converter, during various simulated faults, can
also be checked. This enables the equipment to be partly commissioned off-site. It also
provides the opportunity to detect and correct hardware and software errors or deficiencies in
the control and protection systems.
The factory system test may use a real-time simulator and/or software models.
In the factory system test the complete control system shall be tested. Fault recorders and
sequence of event recorders in case they are "stand alone equipment" may be excluded. If
these recorders are not part of the factory system test, the validity of output signals to these
equipment would be checked during the tests.
Finding and correcting hardware and software errors in the control system is an important
function of the off-site test. Such faults are easier to find and correct off-site rather than during
site tests and commissioning. Correcting such faults reduces the probability of disturbing the
customer power system during the site system test.
4.6.2 Additional simulation test before site system test
If the a.c. network condition in commissioning stage is different from that in the HVDC design
stage, the additional simulation test should be conducted, if specified by the user.

– 14 – 61975 © IEC:2010(E)
Off-line simulation software can be used to analyse short circuit capacity, overvoltage and
power flow, while the real-time simulator may be used for the complete functional performance
tests of the control system.
The additional simulations provide opportunities to:
a) set up the parameters of the control systems and obtain a preliminary check on the
performance of the equipment relative to the specified requirements;
b) check performance of the protective functions of the converter during various simulated
faults;
c) find and correct hardware and software errors in the control system which are easier to find
and correct off-site rather than during site tests and commissioning, and can reduce the
probability of disturbing the customer power system during site system tests.

61975 © IEC:2010(E) – 15 –
Tests Configuration
Converter station test
Converter
terminal
1) Converter unit test
2) Energizing of reactive components
Converter unit
• A.c. filters
• Capacitor banks
• Reactors
3) Changing the d.c. system configuration
4) Electromagnetic compatibility
5) Trip test
6) Open line test
7) Back-to-back test
8) Short circuit test
Converter unit
NOTE Tests in Italic are special load tests as per
5.1.2.5.
IEC  1898/10
Power transmission test
1) Basic operation
• Start and stop sequences and steady state
operation
Pole 1
• Protective blocking and tripping sequences
• Power and current ramping A B
2) Operator control mode transfer
Pole 2
• Control location
• Control mode
• Reactive power control mode
IEC  1899/10
• Operation voltage
• D.c. power automatic control
Configuration
3) Changes of d.c. configuration

4) Switching of primary equipment

• Transformers and tap changers
• A.c. filters and the reactive power compensation
Monopole
devices
Bipole
(earth or metallic return)
• D.c. filters
5) Dynamic performance testing
6) A.c. and d.c. system staged faults
7) Loss of telecom, auxiliaries or redundant equipment Pole 1 Pole 2 Pole 1/2
8) Steady state performance
• The measurement of the system parameters
• Reactive power control end performance
A>B B>A A>B B>A A>B B>A
• Overload/Temperature rise
• Harmonic performance and filter components
IEC  1900/10
rating
• Audible noise
• Loading tests
• Electromagnetic interference test
• Earth electrode test
Trial operation
Figure 4 – Structure of system test

– 16 – 61975 © IEC:2010(E)
5 Converter station test
5.1 General
5.1.1 Environmental specifications
This clause describes the test of each converter station as a unit and the verification of the
HVDC transmission line prior to transmitting power. This group of tests precedes the end-to-
end test.
During the test program, conformance with environmental specifications should be included
where applicable. Preliminary observations of audible noise, radio and PLC interference levels
may be made, and temperature rise of major equipment can be monitored as described in
Clause 6. However, the actual measurement of the above mentioned quantities should be
conducted during end-to-end operation.
5.1.2 General purpose
5.1.2.1 General
The converter station test verifies the correct operation of an individual converter station and
the proper insulation of all main circuit equipment before starting the power transmission tests.
The converter station tests may be divided into low voltage energizing, high voltage energizing,
open line test and load tests.
5.1.2.2 Low voltage energizing / Phasing verification
In order to verify the phasing, the converter main circuit connections and the converter firing
control a low voltage energizing test could be conducted prior to high voltage energizing. The
test verifies the electrical phasing through the main circuit and the control system.
5.1.2.3 High voltage energizing
The high voltage energizing verifies that proper voltage insulation is achieved in the a.c. and
d.c. main circuit equipment.
5.1.2.4 Open line test
The open line tests of the d.c. switchyard and d.c. transmission circuit verify that proper
insulation voltage withstand has been achieved and that the converter firing control and the
valve base electronics function properly.
5.1.2.5 Special load test
A load test (back-to-back or short circuit test) may be conducted, if specifically specified by the
user, to get a provisional verification of the control system, the valve cooling capability and the
main circuit with respect to temperature rise, audible noise and radio interference. Final
verification will be made during power transmission test.
5.1.3 General precondition
Before beginning the converter test, the following equipment shall be verified off voltage and be
available:
a) a.c. switchgear;
b) a.c. filters, capacitor banks and shunt reactors;
c) d.c. filters and switchgear;

61975 © IEC:2010(E) – 17 –
d) converter transformers;
e) thyristor valves and cooling system;
f) station auxiliary service;
g) fire protection system;
h) a.c. and d.c. protection systems;
i) control system;
j) d.c. line or cable (for open line test);
k) sequence of event recorder;
l) alarm system;
m) transient fault recorders.
Prior to the converter tests, detailed procedures and plans should be prepared. As the tests
may involve some disturbance or increased risk to the connected a.c. systems, the operators of
the systems should be consulted.
5.2 Converter unit test
5.2.1 Purpose of test
The test verifies that at the first energization of the converter unit the insulation voltage
withstand is achieved, and checks that the electrical phasing is correct.
5.2.2 Test precondition
Test preconditions are the following:
a) All controls and protections associated with the high voltage equipment shall be verified
and in service. A trip test shall be made shortly before high voltage energizing (see 5.6).
b) Monitoring instrumentation shall be connected and ready.
c) All clamp joints shall have been tightened and the insulators wiped clean.
d) The HVDC transmission line disconnect switch shall be opened and locked.
e) All safety procedures shall have been carried out.
f) A final visual inspection of the high voltage equipment shall be performed and the arrester
counter numbers shall be recorded.
g) The low voltage side of the valves shall be earthed.
5.2.3 Test procedure
5.2.3.1 Low voltage energizing
Test conditions are the following:
a) During the test, all the internal reference voltages in the controls and the firing pulses of the
valve control unit (=VCU) are monitored.
b) The test may be performed by applying 0,5 to 10 kV to the primary side or to the valve side
of the converter transformers with all thyristors short-circuited except one or more thyristors
in each valve.
c) An appropriate resistor or reactor may serve as a load on the d.c. side.
d) Each single valve is represented by a single thyristor level. During the low voltage
energizing test, the valves are de-blocked and the converter is operating in normal or open
line test mode.
NOTE An alternative approach to verify the phasing of the converter main circuit connections and the
interconnections to the converter transformers is a thorough visual inspection of the interconnection scheme and

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comparison with the relevant documentation. This will however include verification that the control sends out a firing
pulse to the correct thyristor.
5.2.3.2 High voltage energizing
Test conditions are the following:
a) Energize the converter transformer with the valves blocked and check the electrical phasing
through the control system.
b) Ensure that the converter transformer tap changers initially at highest position （lowest
valve side voltage) and then are stepped to rated voltage.
c) Keep the transformer energized for a minimum of 6 h.
d) Record a.c. voltage, steady-state and inrush-current, and inspect the equipment for
abnormal sounds and corona discharge during the test.
5.2.3.3 Test acceptance criteria
The test acceptance criteria are the following:
a) No abnormal sound or corona discharge shall occur in the energized equipment.
b) No protection shall operate improperly.
c) Parameters, such as voltage, should be as expected.
5.3 Energizing of reactive components
5.3.1 Individual energizing of reactive components
Reactive components, such as a.c. filters, capacitor banks and shunt reactors are energized
for the first time individually. Combined switching of these elements is described in Clause 6.
5.3.2 Purpose of test
Purposes of the test are the following:
a) to verify that proper voltage insulation is achieved;
b) to verify that the a.c. filters, capacitor banks and shunt reactors are balanced between the
three phases;
c) to confirm the no-load currents and voltages of the protections, if any.
5.3.3 Test precondition
Test preconditions are the following:
a) All controls and protections (main and backup) associated with the high voltage equipment
shall be verified and in service. A trip test shall be made shortly before high voltage
energizing.
b) AC filter tuning shall be completed.
c) AC filters and shunt capacitors shall have been balanced.
d) All clamp joints shall have been tightened and the insulators wiped clean.
e) All safety procedures shall have been carried out.
f) A final visual inspection of the h
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