IEC TR 63500:2024

IEC TR 63500 ®
Edition 1.0 2024-10
TECHNICAL
REPORT
colour
inside
Unified power flow controller (UPFC) installations – System tests

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IEC TR 63500 ®
Edition 1.0 2024-10
TECHNICAL
REPORT
colour
inside
Unified power flow controller (UPFC) installations – System tests

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.99  ISBN 978-2-8322-9828-2

– 2 – IEC TR 63500:2024 © IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Objectives of system tests . 9
4.1 Purpose . 9
4.2 Basic principles . 9
4.3 Items of system tests . 10
5 Preconditions of system tests . 15
5.1 Basic conditions . 15
5.2 Preconditions of system tests for the UPFC installation . 15
5.3 Preconditions of system tests for the AC grid . 15
6 Converter unit tests . 16
6.1 Trip test . 16
6.1.1 Purpose of test . 16
6.1.2 Test preconditions . 16
6.1.3 Test procedure . 16
6.1.4 Evaluation of test results . 17
6.2 Energizing test of the shunt transformer . 17
6.2.1 Purpose of test . 17
6.2.2 Test preconditions . 17
6.2.3 Test procedure . 17
6.2.4 Evaluation of test result . 17
6.3 Energizing test of the series transformer . 17
6.3.1 Purpose of test . 17
6.3.2 Test preconditions . 18
6.3.3 Test procedure . 18
6.3.4 Evaluation of test results . 19
6.4 Energizing test of the shunt converter . 19
6.4.1 Purpose of test . 19
6.4.2 Test preconditions . 20
6.4.3 Test procedure . 20
6.4.4 Evaluation of test results . 20
6.5 Energizing test of the series converter . 20
6.5.1 Purpose of test . 20
6.5.2 Test preconditions . 20
6.5.3 Test procedure . 21
6.5.4 Evaluation of test results . 21
6.6 Output phase sequence verification test of the shunt converter . 21
6.6.1 Purpose of test . 21
6.6.2 Test preconditions . 21
6.6.3 Test procedure . 22
6.6.4 Evaluation of test results . 23
6.7 Output phase sequence verification test of the series converter . 23
6.7.1 Purpose of test . 23

6.7.2 Test preconditions . 23
6.7.3 Test procedure . 23
6.7.4 Evaluation of test results . 24
7 System function and performance tests . 24
7.1 Initial operation tests . 24
7.1.1 Purpose of test . 24
7.1.2 Test preconditions . 25
7.1.3 Test procedure . 25
7.1.4 Evaluation of test results . 26
7.2 Steady-state performance tests. 26
7.2.1 Purpose of test . 26
7.2.2 Test preconditions . 27
7.2.3 Test procedure . 27
7.2.4 Evaluation of test results . 28
7.3 Dynamic performance tests . 28
7.3.1 Purpose of test . 28
7.3.2 Test preconditions . 28
7.3.3 Test procedure . 29
7.3.4 Evaluation of test results . 30
7.4 Fault switching tests of control system . 30
7.4.1 Purpose of test . 30
7.4.2 Test preconditions . 30
7.4.3 Test procedure . 30
7.4.4 Evaluation of test results . 31
7.5 Transfer tests of auxiliary system . 31
7.5.1 Purpose of test . 31
7.5.2 Test preconditions . 32
7.5.3 Test procedure . 32
7.5.4 Evaluation of test results . 32
7.6 Grid control function tests (optional) . 32
7.6.1 Purpose of test . 32
7.6.2 Test preconditions . 33
7.6.3 Test procedure . 33
7.6.4 Evaluation of test results . 34
7.7 Other operation mode tests . 34
7.7.1 General . 34
7.7.2 STATCOM mode tests . 34
7.7.3 SSSC mode tests . 35
7.8 Heavy load and overload tests . 36
7.8.1 Purpose of test . 36
7.8.2 Test preconditions . 36
7.8.3 Test procedure . 37
7.8.4 Special measurements during the test . 37
7.9 Artificial short circuit test on AC grid (optional). 37
7.9.1 Purpose of test . 37
7.9.2 Test preconditions . 37
7.9.3 Test procedure . 38
7.9.4 Evaluation of test results . 38
8 Trial operation . 38

– 4 – IEC TR 63500:2024 © IEC 2024
8.1 Purpose of test . 38
8.2 Test preconditions . 38
8.3 Test procedure . 39
8.4 Evaluation of test results . 39
Annex A (informative) Artificial short circuit test example of a UPFC installation . 40
A.1 Purpose of test . 40
A.2 Test preconditions . 40
A.2.1 Components and placement of artificial single-phase-to-earth fault
generating device . 40
A.2.2 Instalment of artificial single-phase-to-earth fault generating device . 41
A.3 Test procedure . 42
A.3.1 Testing fire of the artificial transmitting device . 42
A.3.2 Official testing procedure . 42
Bibliography . 43

Figure 1 – Structure diagram of the UPFC installation . 10
Figure 2 – Energizing test of the shunt transformer . 12
Figure 3 – Energizing test of the series transformer . 12
Figure 4 – Energizing test of the shunt converter . 13
Figure 5 – Energizing test of the series converter . 13
Figure 6 – Output phase sequence verification test of the shunt converter . 13
Figure 7 – Output phase sequence verification test of the series converter . 13
Figure 8 – System function and performance tests of UPFC . 14
Figure 9 – Other operation mode tests – STATCOM mode . 14
Figure 10 – Other operation mode tests – SSSC mode . 14
Figure 11 – Trial operation . 14
Figure 12 – Test procedure diagram of series transformer energizing test . 19
Figure 13 – Test procedure diagram of output phase sequence verification test of the
shunt converter . 22
Figure 14 – Test procedure diagram of output phase sequence verification test of the
series converter . 24
Figure A.1 – The artificial single-phase-to-earth fault generating device. 41

Table 1 – Test stage, item and configuration of system tests . 11

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UNIFIED POWER FLOW CONTROLLER (UPFC) INSTALLATIONS –
SYSTEM TESTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC TR 63500 has been prepared by subcommittee 22F: Power electronics for electrical
transmission and distribution systems, of IEC technical committee 22: Power electronic systems
and equipment. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
22F/781/DTR 22F/795/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.

– 6 – IEC TR 63500:2024 © IEC 2024
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
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The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document 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.

INTRODUCTION
IEC TR 63262:2019 introduces the importance of the system tests of unified power flow
controller (UPFC) installations and gives the test items of the system tests. However, the details
of the system tests of UPFC installations, including test methods and test procedures, are not
given. For the commercial use of UPFC installations, this document provides the details of the
system tests of UPFC installations for reference. The system tests are to verify the quality of
UPFC after on-site installation and integration, the coordination between a UPFC installation
and the grid, the fault ride-through performance of the UPFC installation and so on, which make
the commercial operation of the UPFC installation more efficient and safer.
This document summarizes the system test experience of the existing UPFC projects, and the
content has been verified by several years of stable operation of the UPFC projects.

– 8 – IEC TR 63500:2024 © IEC 2024
UNIFIED POWER FLOW CONTROLLER (UPFC) INSTALLATIONS –
SYSTEM TESTS
1 Scope
This document provides the general information, items, conditions, and evaluation of test results
for on-site system tests of unified power flow controller (UPFC) installations based on modular
multi-level converter (MMC) technology. For special functions or performances that are claimed
by specific projects, some extra test items not included in this document can be added according
to the technical specification.
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 TR 63262:2019, Performance of unified power flow controller (UPFC) in electric power
systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TR 63262 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
unified power flow controller
UPFC
equipment which has two (or more) voltage sourced converters (VSCs) sharing common DC
bus connected to the transmission system in parallel and in series, and can control the line
impedance, voltage amplitude and phase angle at the same time
[SOURCE: IEC TR 63262:2019, 3.1.1]
3.2
system test
test verifying functions and performances of UPFC installations as a whole as well as the
interaction with adjacent AC systems
[SOURCE: IEC 61975:2010 and IEC 61975:2010/AMD1:2016, 3.1.2, modified – The words
"HVDC system" have been changed to "UPFC installations".]
3.3
converter unit test
test verifying functions and performances of converter units, including the shunt unit and series
unit
3.4
subsystem test
test verifying functions and performances of subsystems, such as converter system, water
cooling system, relay protection system
3.5
thyristor bypass switch
TBS
power electronic switch with anti-parallel connected thyristors between the converter and the
series transformer valve-side winding
[SOURCE: IEC TR 63262:2019, 3.1.6]
3.6
mechanical bypass switch
MBS
mechanical switch between the grid-side winding terminals of the series transformer
4 Objectives of system tests
4.1 Purpose
The system tests complete the commissioning of a UPFC installation. For the user, the
completion of the system tests marks the beginning of the commercial operation of the UPFC
installation. For the supplier, the system tests verify the suitability of the installed UPFC
equipment and the functional completeness of the UPFC system. Moreover, adjustments and
optimizations of the UPFC installation are made according to the results of system tests.
The system tests are to demonstrate that the requirements and stipulations in the contract are
met.
The system tests consist of five major aspects:
a) UPFC installation equipment;
b) UPFC installation control and protection equipment and their settings;
c) environmental considerations;
d) interaction between the parallel unit and series unit;
e) system performance when the UPFC installation jointly operated with connected AC
systems.
4.2 Basic principles
The basic principles for the system tests of the UPFC installation are as follows.
a) For the safety of the UPFC installation, the system tests are conducted until the completion
of equipment factory tests, equipment on-site tests and on-site subsystem tests;
b) All designed functions and performances are tested to confirm that all technical
requirements are satisfied;
c) The system test plan is agreed between the supplier and the user.

– 10 – IEC TR 63500:2024 © IEC 2024
4.3 Items of system tests
A typical structure of the UPFC installation is illustrated in Figure 1, consisting of the main
circuit (shunt unit and series unit) and a control and protection system. The main circuit consists
of two VSCs connected back-to-back by the DC bus, and the AC terminals are connected to the
AC grid via two transformers: the shunt converter is connected to the transmission line in
parallel via shunt transformer, and the series converter is connected to the transmission line
serially via series transformer. The shunt converter and shunt transformer are the main
components of the shunt unit. The series converter, TBS, MBS and series transformer are the
main components of the series unit. The TBS is connected between the series converter and
the series transformer.
Figure 1 – Structure diagram of the UPFC installation
The typical control structure of the UPFC installation generally includes a system control, a
converter control, and a valve control. The converter control and valve control are equipped
independently for the series converter and shunt converter.
a) System control
Coordinates the control objects and targets of different converters, and mainly achieves the
coordination control among substations and among different converters.
The system control functions include the following:
– power coordination control of power grid;
– power control of transmission interface;
– emergency power control and emergency voltage control of power grid;
– power oscillation damping control, etc.

b) Converter control
Mainly accomplishes the multiple basic control functions of converters.
The shunt converter control includes the following:
– DC voltage control;
– AC voltage control or reactive power control;
– overload limitation control (if applicable).
The series converter control includes the following:
– active power control;
– reactive power control;
– emergency current control;
– impedance control (if applicable);
– overload limitation control of transmission line (if applicable).
c) Valve control
Direct control and monitoring of valves.
The system test items of the UPFC installation are listed in Table 1. For some special functions
or performances required by the user, the system test items can be modified accordingly.
The system tests of the UPFC installation are divided into three stages: stage I involves testing
the converter unit in the UPFC installation, stage II involves testing the system function and
performance of the UPFC installation, and stage III involves trial operation of the UPFC
installation.
The system tests follow the structure of the UPFC installation, starting from the smallest device,
usually a transformer, then the least complex operational unit, usually a converter, and ending
with the entire system in operation. Table 1 illustrates the test objects related to each test item.
Table 1 – Test stage, item and configuration of system tests
Stage No. Test item Configuration
1 Trip test The control and protection systems
2 Energizing test of
the shunt See Figure 2.
transformer
3 Energizing test of
the series See Figure 3.
transformer
4 Energizing test of
See Figure 4.
the shunt converter
Stage I
5 Energizing test of
See Figure 5.
the series converter
6 Output phase
sequence
See Figure 6.
verification test of
the shunt converter
7 Output phase
sequence
See Figure 7.
verification test of
the series converter
– 12 – IEC TR 63500:2024 © IEC 2024
Stage No. Test item Configuration
8 Initial operation
tests
9 Steady-state
performance tests
10 Dynamic
performance tests
11 Fault switching
tests of control See Figure 8.
system
12 Transfer tests of
auxiliary system
Stage II
13 Grid control function
tests (optional)
14 Heavy load and
overload tests
15 Artificial short
circuit test on AC
grid (optional)
16 Other operation See Figure 9.
mode tests
a) STATCOM mode
See Figure 10.
b) SSSC mode
Stage III 17 Trial operation See Figure 11.

Figure 2 – Energizing test of the shunt transformer

Figure 3 – Energizing test of the series transformer

Figure 4 – Energizing test of the shunt converter

Figure 5 – Energizing test of the series converter

Figure 6 – Output phase sequence verification test of the shunt converter

Figure 7 – Output phase sequence verification test of the series converter

– 14 – IEC TR 63500:2024 © IEC 2024

Figure 8 – System function and performance tests of UPFC

Figure 9 – Other operation mode tests – STATCOM mode

Figure 10 – Other operation mode tests – SSSC mode

Figure 11 – Trial operation
5 Preconditions of system tests
5.1 Basic conditions
The commissioning of a UPFC installation involves all the contract parties. The complexity and
diversified aspects regarding the system tests require thorough planning and scheduling, the
cooperation of all involved parties, and complete and structured documentation.
a) Operators are sufficiently trained.
b) Permission for each test procedure is available by the substation manager.
c) Safety and security instructions are made available to all personnel.
d) The system test program is approved.
e) Power profiles for each test are determined by both the supplier and user through
negotiation.
f) Communications between operators and test personnel are established.
g) All necessary testing equipment is calibrated and operational.
5.2 Preconditions of system tests for the UPFC installation
The basic preconditions for the system tests regarding the UPFC installation are listed below,
and other important preconditions are listed in each test.
a) The subsystem tests of the UPFC installation are completed, and all results are satisfied.
The main equipment is ready for operation. The water cooling system of the converter valves
is in service.
b) The temporary ground connection for the on-site high voltage test is removed. Any
temporary structure in the UPFC installation is removed, and the testing sections are
isolated from other sections.
c) All auxiliary systems, including the auxiliary power system, fire prevention system, heating,
ventilation and air conditioning (HVA/C) system as well as lighting, are installed and
operational.
d) Preliminary off-site tests of the control and protection system are conducted before delivery
to verify the functionality of the UPFC control and protection system.
e) The UPFC monitoring and its communication, control and protection system are set correctly
and operational.
5.3 Preconditions of system tests for the AC grid
The basic preconditions for the system tests regarding the AC grid are listed below, and other
important preconditions are listed in each test.
a) The AC grid configuration and power profiles are adjusted according to the system test
program.
b) The transmission lines connected to the UPFC installation in series and their relevant
protections are operational.
c) The relevant safety devices in the grid are set correctly and operational.
d) In order to formulate the system test plan, relevant simulations are conducted to satisfy the
safety and stability requirements for the equipment and system before the system tests,
with an emphasis on power flow, stability and overvoltage.

– 16 – IEC TR 63500:2024 © IEC 2024
6 Converter unit tests
6.1 Trip test
6.1.1 Purpose of test
The test is to verify protection action (especially the functionality of the protective trip circuits
of the equipment in the converter unit) and examine the records of the control system.
6.1.2 Test preconditions
The test preconditions are the following.
a) All the electric equipment in the UPFC installation is disconnected from the AC grid.
b) All control and protection systems (main and backup) associated with high voltage
equipment are operational and their functionality and performance are verified.
c) All alarm and monitoring (including recording sequence of events) systems are verified and
in service.
d) All safety procedures, including a visual inspection of high voltage equipment, are carried
out before the test.
6.1.3 Test procedure
6.1.3.1 General
Trip signals are initiated from different devices, including but not limited to the tests listed in
6.1.3.2 to 6.1.3.7.
6.1.3.2 Protection trip test of converters
Initiate a trip signal from the protection trip terminal of the converter; the AC circuit breaker in
grid side trips in this case.
6.1.3.3 Protection trip test of transformers
Initiate a trip signal from the protection trip terminal of the transformer; the AC circuit breaker
in grid side trips in this case.
6.1.3.4 Protection trip test of the series unit
Initiate a trip signal from the protection trip terminal of the series unit; the TBS and bypass
switch close in this case.
6.1.3.5 Protection trip test of the transmission line
Initiate a trip signal from the protection trip terminal of the transmission line; the line protection
trips. In addition, the TBS and MBS close in this case.
6.1.3.6 Protection trip test of the water cooling system
Initiate a trip signal from the protection trip terminal of the water cooling system; the AC circuit
breaker in grid side trips in this case.
6.1.3.7 Trip test of the emergency switch-off button
Press the emergency switch-off button in the control room; the AC circuit breaker in grid side
trips in this case.
6.1.4 Evaluation of test results
The evaluation of test results includes the following.
a) When activated by either position protection or manually by the emergency switch-off button,
the AC circuit breaker in grid side trips without any fault.
b) No abnormal alarm occurs.
6.2 Energizing test of the shunt transformer
6.2.1 Purpose of test
This test is to verify the insulation strength of the shunt transformer satisfies the designed
requirements and the electrical phasing of the shunt transformer is correct.
6.2.2 Test preconditions
The test preconditions are the following.
a) The on-site test of the shunt transformer is completed.
b) The trip test is completed before high voltage energizing (see 6.1).
c) The position of the voltage tap of the shunt transformer is correct.
d) The cooling system of the shunt transformer is in normal operation.
e) The shunt transformer is disconnected from the AC grid and the shunt converter.
f) The arrestor counter numbers are recorded.
6.2.3 Test procedure
The test procedure is the following.
a) Energize the shunt transformer for a certain time to complete the operational inspection and
live detection, for example in some UPFC projects, no less than 30 min.
b) Record the inrush current and overvoltage.
c) Visually inspect all devices.
ferro-resonance during the
d) Pay special attention to abnormal sounds, corona discharge and
test.
e) Test the voltage tap control function using the manual mode and automatic mode separately.
f) Perform chromatographic analysis of the shunt transformer oil after the test.
g) Deenergize the shunt transformer.
6.2.4 Evaluation of test result
The evaluation of test results includes the following.
a) No protection function is activated during the test.
b) The voltage phasing of shunt transformer is correct.
c) No abnormal sound or corona discharge or ferro-resonance occurs.
d) Measurements, such as the noise, overvoltage and inrush current, meet the requirements.
6.3 Energizing test of the series transformer
6.3.1 Purpose of test
This test is to verify the insulation strength of the series transformer satisfies the designed
requirements and the electrical phasing of the shunt transformer is correct.

– 18 – IEC TR 63500:2024 © IEC 2024
6.3.2 Test preconditions
The test preconditions are the following.
a) The on-site test of the series transformer is completed.
b) The trip test is completed before high voltage energizing (see 6.1).
c) The cooling system of the series transformer is in normal operation.
d) The series transformer is disconnected from the AC grid and the series converter.
e) The windings of the series transformer on both the grid side and valve side are bypassed
f) The arrestor counter numbers are recorded.
6.3.3 Test procedure
There are two methods to conduct this test according to the structure of UPFC installation.
Based on the UPFC structure in Figure 12 a), the test procedure of the first method is the
following.
a) Energize the series transformer through closing the AC circuit breaker in grid side for a
certain time as shown in step 1 to complete the operational inspection and live detection,
for example in some UPFC projects, no less than 30 min.
b) Open the MBS after energizing the series transformer to insert the series transformer to the
transmission line as shown in step 2.
c) Record the inrush current and overvoltage.
d) Close the MBS to bypass the series transformer as shown in step 3.
e) Visually inspect all devices.
f) Pay special attention to abnormal sounds, corona discharge and ferro-resonance during the
test.
g) Deenergize the series transformer.
h) Perform chromatographic analysis of the series transformer oil after the test.
Based on the UPFC structure in Figure 12 b), the test procedure of the second method is the
following.
1) Energize the series transformer through closing the AC circuit breaker in series transformer
side for a certain time as shown in steps 1, 2 and 3 to complete the operational inspection
and live detection, for example in some UPFC projects, no less than 30 min.
2) Open the MBS after energizing the series transformer to insert the series transformer to the
transmission line as shown in step 4.
3) Record the inrush current and overvoltage.
4) Close the MBS to bypass the series transformer.
5) Visually inspect all devices.
6) Pay special attention to abnormal sounds, corona discharge and ferro-resonance during the
test.
7) Deenergize the series transformer.
8) Perform chromatographic analysis of the series transformer oil after the test.

a) Method 1
b) Method 2
Figure 12 – Test procedure diagram of series transformer energizing test
6.3.4 Evaluation of test results
The evaluation of test results includes the following.
a) No protection function is activated during the test.
b) The voltage phasing of series transformer is correct.
c) No abnormal sound or corona discharge or ferro-resonance occurs.
d) Measurements, such as the noise, overvoltage and inrush current, meet the requirements.
6.4 Energizing test of the shunt converter
6.4.1 Purpose of test
This test is to verify that the shunt converter is energized safely and the function of phase
locked loop is correct.
– 20 – IEC TR 63500:2024 © IEC 2024
6.4.2 Test preconditions
The test preconditions are the following.
a) The on-site test of the shunt converter is completed.
b) The trip test is completed before high voltage energizing (see 6.1).
c) The energizing test of shunt transformer is completed (see
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