IEC TS 62910:2020
(Main)Utility-interconnected photovoltaic inverters - Test procedure for under voltage ride-through measurements
Utility-interconnected photovoltaic inverters - Test procedure for under voltage ride-through measurements
IEC TS 62910:2020 is available as IEC TS 62910:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC TS 62910:2020 provides a test procedure for evaluating the performance of Under Voltage Ride-Through (UVRT) functions in inverters used in utility-interconnected Photovoltaic (PV) systems. This document is most applicable to large systems where PV inverters are connected to utility high voltage (HV) distribution systems. However, the applicable procedures may also be used for low voltage (LV) installations in locations where evolving UVRT requirements include such installations, e.g. single-phase or 3-phase systems. The assessed UVRT performance is valid only for the specific configuration and operational mode of the inverter under test. Separate assessment is required for the inverter in other factory or user-settable configurations, as these may cause the inverter UVRT response to behave differently. This second edition cancels and replaces the first edition issued in 2015 and constitutes a technical revision.
General Information
Standards Content (sample)
IEC TS 62910
Edition 2.0 2020-07
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for under voltage
ride-through measurements
IEC TS 62910:2020-07(en)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2020 IEC, Geneva, Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary
(IEV) online.IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have beenIEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
---------------------- Page: 2 ----------------------
IEC TS 62910
Edition 2.0 2020-07
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for under voltage
ride-through measurements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-8383-7
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission---------------------- Page: 3 ----------------------
– 2 – IEC TS 62910:2020 © IEC 2020
CONTENTS
FOREWORD ........................................................................................................................... 4
1 Scope .............................................................................................................................. 7
2 Normative references ...................................................................................................... 7
3 Terms, definitions, symbols and abbreviated terms .......................................................... 7
3.1 Terms, definitions and symbols ............................................................................... 7
3.2 Abbreviated terms ................................................................................................... 9
4 Test circuit and equipment ............................................................................................. 10
4.1 General ................................................................................................................. 10
4.2 Test circuit ............................................................................................................ 10
4.3 Test equipment ..................................................................................................... 10
4.3.1 Measuring instruments................................................................................... 10
4.3.2 DC source ..................................................................................................... 11
4.3.3 Short-circuit emulator .................................................................................... 11
4.3.4 Converter based grid simulator ...................................................................... 14
5 Test ............................................................................................................................... 14
5.1 Test protocol ......................................................................................................... 14
5.2 Test curve ............................................................................................................. 16
5.3 Test procedure ...................................................................................................... 17
5.3.1 Pre-test ......................................................................................................... 17
5.3.2 No-load test ................................................................................................... 17
5.3.3 Tolerance ...................................................................................................... 17
5.3.4 Load test ....................................................................................................... 17
6 Assessment criteria ....................................................................................................... 18
Annex A (informative) Circuit faults and voltage drops ......................................................... 19
A.1 Fault types ............................................................................................................ 19
A.2 Voltage drops ....................................................................................................... 21
A.2.1 General ......................................................................................................... 21
A.2.2 Three-phase short-circuit fault ....................................................................... 22
A.2.3 Two-phase short-circuit fault with ground ....................................................... 22
A.2.4 Two-phase short-circuit fault without ground .................................................. 23
A.2.5 Single-phase short-circuit fault with ground ................................................... 24
Annex B (informative) Determination of critical performance values in UVRT testing ............ 26
B.1 General ................................................................................................................. 26
B.2 Drop depth ratio .................................................................................................... 26
B.3 Ride-through time ................................................................................................. 26
B.4 Reactive current.................................................................................................... 26
B.5 Active power ......................................................................................................... 27
Annex C (informative) Requirements of the UVRT curve ...................................................... 28
C.1 General ................................................................................................................. 28
C.2 UVRT curve .......................................................................................................... 28
C.3 Test points ............................................................................................................ 28
Bibliography .......................................................................................................................... 29
Figure 1 – Testing circuit diagram ......................................................................................... 10
Figure 2 – Short-circuit emulator ........................................................................................... 12
---------------------- Page: 4 ----------------------IEC TS 62910:2020 © IEC 2020 – 3 –
Figure 3 – Converter device example .................................................................................... 14
Figure 4 – UVRT curve example ........................................................................................... 16
Figure 5 – Tolerance of voltage drop..................................................................................... 17
Figure A.1 – Grid fault diagram ............................................................................................. 21
Figure A.2 – Diagram of voltage vector for three-phase short-circuit fault ............................. 22
Figure A.3 – Diagram of voltage vector of two-phase (BC) short-circuit fault with
ground .................................................................................................................................. 23
Figure A.4 – Diagram of voltage vector of two-phase (BC) short-circuit fault ......................... 24
Figure A.5 – Diagram of voltage vector of single-phase (A) short-circuit fault with
ground .................................................................................................................................. 25
Figure B.1 – Determination of reactive current output ........................................................... 27
Figure B.2 – Determination of active power recovery ............................................................ 27
Figure C.1 – The typical curve of UVRT ................................................................................ 28
Table 1 – Accuracy of measurements ................................................................................... 11
Table 2 – Fault type and switch status .................................................................................. 13
Table 3 – Test specification for UVRT (Indicative) ................................................................. 15
Table A.1 – Short-circuit paths for different fault types .......................................................... 19
Table A.2 – Amplitude and phase changes in three-phase short-circuit fault ......................... 22
Table A.3 – Amplitude and phase changes in two-phase (BC) ............................................... 23
Table A.4 – Amplitude and phase changes in two-phase (BC) short-circuit fault .................... 24
Table A.5 – Amplitude and phase changes in single-phase (A) ............................................. 25
---------------------- Page: 5 ----------------------– 4 – IEC TS 62910:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
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.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a Technical
Specification when• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.IEC TS 62910, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.---------------------- Page: 6 ----------------------
IEC TS 62910:2020 © IEC 2020 – 5 –
This second edition cancels and replaces the first edition issued in 2015, and constitutes a
technical revision.It remains a TS because it is limited to providing recommended practices for UVRT testing in
the context of non-uniform grid-codes lacking international consensus, and the rapid
development of test technology in recent years.The main technical changes with regard to the previous edition are as follows:
Clause Previous edition Present edition
the voltage support of EUT in accordance with the K-factor is to be supplied by the EUT
the voltage drops. The K-factor is to be manufacturer meeting additional requirements
3.1.12specified by the EUT manufacturer imposed by national standards and/or local codes
Back to Back circuit Back to Back circuitA A
B B
Figure 2
C C
Grid Grid
(optional) (optional)
The test circuit essentially comprises a voltage The test circuit essentially comprises a voltage
4.3.4 source with a low internal resistance combined source with a low internal resistance combined
with broadband amplifiers...... optionally with broadband amplifiers......d The test should be carried out under specified d The test should be carried out under specified
K-factor provided by manufacture meetingK-factor provided by local manufacture.
Table 3
additional requirements imposed by national
standards and/or local codes.
1,2
1,2
1,1
1,1
LVRT curve
LVRT curve
Keep connecting to the grid
Keep connecting to the grid 1,0
1,0
highest point
0,9
0,9
inflection point
0,8 inflection point 0,8
0,7 inflection point 0,7 inflection point
0,6 0,6
0,5 0,5
May cut off from the grid May cut off from the grid
Figure 4
0,4 0,4
0,3 inflection point 0,3 inflection point
0,2
0,2
Lowest point
Lowest point
0,1
0,1
t0 t1 t2 t3 4 t
t t t t 4
0 1 2 3
Time (s)
Time (s)
NOTE The example shows two types of points The example shows three types of points on the
on the UVRT curve: the lowest point and the UVRT curve: the highest point, the lowest point
5.2inflection point. Tests must be carried out at and the inflection point. Tests shall be carried out
both types of points at above types of points.Prior to the fault simulation tests, the EUT Prior to the fault simulation tests, the EUT should
should run in normal operating mode. The run in normal operating mode. The selected
5.3.1 selected UVRT curve should be used to identify UVRT curve should be used to identify voltage
voltage drop points, including the lowest point drop points, including the highest point, the
and the inflection point, ...... lowest point and the inflection point, ......Voltage of PCC ( p.u. )
Voltage of PCC
( p.u. )
---------------------- Page: 7 ----------------------
– 6 – IEC TS 62910:2020 © IEC 2020
The text of this Technical Specificationis based on the following documents:
Draft TS Report on voting
82/1607/DTS 82/1640A/RVDTS
Full information on the voting for the approval of this Technical Specification 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.
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 correctunderstanding of its contents. Users should therefore print this document using a
colour printer.---------------------- Page: 8 ----------------------
IEC TS 62910:2020 © IEC 2020 – 7 –
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR UNDER VOLTAGE
RIDE-THROUGH MEASUREMENTS
1 Scope
This document provides a test procedure for evaluating the performance of Under Voltage
Ride-Through (UVRT) functions in inverters used in utility-interconnected Photovoltaic (PV)
systems.This document is most applicable to large systems where PV inverters are connected to utility
high voltage (HV) distribution systems. However, the applicable procedures may also be used
for low voltage (LV) installations in locations where evolving UVRT requirements include such
installations, e.g. single-phase or 3-phase systems.The assessed UVRT performance is valid only for the specific configuration and operational
mode of the inverter under test. Separate assessment is required for the inverter in other
factory or user-settable configurations, as these may cause the inverter UVRT response to
behave differently.The measurement procedures are designed to be as non-site-specific as possible, so that
UVRT characteristics measured at one test site, for example, can also be considered valid at
other sites.This document is for testing of PV inverters, though it contains information that may also be
useful for testing of a complete PV power plant consisting of multiple inverters connected at a
single point to the utility grid. It further provides a basis for utility-interconnected PV inverter
numerical simulation and model validation.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 TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms, definitions and symbols
For the purposes of this document, the terms and definitions in IEC TS 61836 and the
following 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
---------------------- Page: 9 ----------------------
– 8 – IEC TS 62910:2020 © IEC 2020
3.1.1
drop depth
magnitude of voltage drop during a fault or simulated fault, as a percentage of the nominal
supply voltage3.1.2
double drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of point of
common coupling (PCC), followed after a short time by a voltage recovery, which happens
twiceNote 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.3.1.3
equipment under test
EUT
equipment on which these tests are performed and refers to the utility-interconnected PV
inverter. During test period, EUT is connected with PV simulator instead of real PV modules
on the direct current (DC) side, while alternating current (AC) side is connected with grid
3.1.4output reactive current of EUT
3.1.5
under voltage ride through
UVRT
capability of an inverter to continue generating power to connected loads during a limited
duration loss or drop of grid voltage3.1.6
maximum power point tracking
MPPT
control strategy of operation at maximum power point or nearby
3.1.7
EUT
access point of the EUT during the test
3.1.8
rated power of EUT
3.1.9
point of common coupling
PCC
point of a power supply network, electrically nearest to a particular load, at which other loads
are, or may be, connectedNote 1 to entry: These loads can be either devices, equipment or system, or distinct customer’s installations.
Note 2 to entry: In some applications, the term “point of common coupling” is restricted to public networks.
[SOURCE: IEC 60050-161:1990, 161-07-15]---------------------- Page: 10 ----------------------
IEC TS 62910:2020 © IEC 2020 – 9 –
3.1.10
proportionality constant K
K-factor
the K-factor is to be supplied by the EUT manufacturer meeting additional requirements
imposed by national standards and/or local codes3.1.11
PV array simulator
simulator that has I-V characteristics equivalent to a PV array
3.1.12
EUT
apparent short-circuit power at N
EUT
S = I × U , I refer to short-circuit current at N during the no-load test
EUT sc N sc EUT
3.1.13
single drop
sudden decline of the nominal voltage to a value below 90 % of the voltage of PCC, followed
after a short time by a voltage recovery, which happens onceNote 1 to entry: Voltage changes which do not reduce the voltage to below 90 % of the voltage of PCC are not
considered to be voltage drops.3.1.14
grid
grid short-circuit impedance value of the main point (MP) 1 (see Figure 1)
3.1.15
impedance value between the fault point and PCC
3.1.16
impedance value between the fault point and EUT
3.2 Abbreviated terms
AC alternating current
A/D analog to digital
DC direct current
EUT equipment under test
HV high voltage
LV low voltage
MV middle voltage
PV photovoltaic
RMS root mean square
UVRT under voltage ride through
---------------------- Page: 11 ----------------------
– 10 – IEC TS 62910:2020 © IEC 2020
4 Test circuit and equipment
4.1 General
The circuits and equipment described in this clause are developed to allow tests that simulate
the full range of anticipated grid faults, including:• Single phase to ground fault (any phase).
• Two phase isolated fault, between any two phases.
• Two phase grounded fault, involving any two phases.
• Three phase short-circuit fault.
A full discussion of these faults and the resulting impact on voltage magnitude and phase
angles is included in Annex A.The short circuit emulator and grid simulator described in 4.3.3 and 4.3.4 are informative
examples and are not intended to restrict design flexibility. Other designs may be used to
achieve equivalent test functionality.4.2 Test circuit
The UVRT test circuit includes a DC source, the EUT, a grid fault simulator and the grid. A PV
simulator (or PV array) provides input energy for the EUT. The output of the EUT is connected
to the grid via a grid fault simulator, as shown in Figure 1.NOTE MP1 is the measurement point between the grid and the grid fault simulator; MP2 is the measurement point
at the high voltage side of the transformer; MP3 is the measurement point at the low voltage side of the
transformer.Figure 1 – Testing circuit diagram
4.3 Test equipment
4.3.1 Measuring instruments
Waveforms shall be measured by a device with memory function, for example, a storage or
digital oscilloscope, or a high speed data acquisition device. Accuracy of the oscilloscope or
data acquisition system should be at least 0,2 % of full scale. The analogue to A/D of the
measurement device shall have at least 12 bit resolution (in order to maintain the required
measurement accuracy).Voltage transformers and current transformers are the required sensors for measurement.
The accuracy of the transducers should be 0,5 % of full scale or better. It is necessary to
select the transducer measuring range depending on the normal value of the signal to be
measured. The selected measuring range shall not exceed 150 % of the normal value of the
measured signal. The transducer accuracy requirements are shown in Table 1.---------------------- Page: 12 ----------------------
IEC TS 62910:2020 © IEC 2020 – 11 –
Table 1 – Accuracy of measurements
Measurement device Accuracy
Data acquisition device 0,2 % full scale
Voltage transformer 0,5 % full scale
Current transformer 0,5 % full scale
4.3.2 DC source
A PV array, PV array simulator or controlled DC source with PV characteristics may be used
as the DC power source to supply input energy for the UVRT test. As the EUT input source,
the DC power source shall be capable of supplying the EUT maximum input power and other
power levels during the test, at minimum and maximum input operating voltages of the EUT.
The PV simulator should emulate the current/voltage characteristic of the PV module or PV
array for which the EUT is designed. The response time of a PV simulator should not be
longer than the MPP tracking response time of EUT.For a EUT under test without galvanic isolation between the DC side and AC side, the output
of the PV simulator shall not be earthed.The equivalent capacitance between the output of the PV simulator and earth should be as
low as possible in order to minimize the impact on the EUT.A PV array used as the EUT input source shall be capable of matching the EUT input power
levels specified by the test conditions. It is necessary to select a period of time in which the
solar irradiance is stable and does not vary more than 5 % during the test.4.3.3 Short-circuit emulator
As part of the grid simulator device, the short-circuit emulator is used to create the voltage
drops due to short-circuits between the two or three phases, or between one or two phases to
ground, via the impedance network Z and Z as shown in the test device layout in Figure 2.
1 2---------------------- Page: 13 ----------------------
– 12 – IEC TS 62910:2020 © IEC 2020
Figure 2 – Short-circuit emulator
The impedance Z is used to limit the effect of the short circuit on the utility service that
powers the test circuit. The sizing of Z shall therefore account for all test sequences to be
performed and limit the short-circuit current taken from the grid to values that do not cause an
excessive reduction of the grid voltage. Considering an acceptable voltage reduction of at
most 5 % when performing the test, the minimum value of Z shall be at least 20 × Z ,
1 Gridwhere Z is the grid short-circuit impedance measured at the test circuit connection point.
GridTo ensure that the test is realistic, however, the apparent short-circuit power (S ) available
EUTat the EUT connection node N should be at least equal to 3×Pn, where Pn is the rated
EUTpower of the EUT (minimum value S > 3 × Pn, recommended 5 × Pn < S < 6 × Pn). This
EUT EUTmeans during the shor
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.