Utility-interconnected photovoltaic inverters - Test procedure for over voltage ride-through measurements

IEC TS 63217:2021 provides a test procedure for evaluating the performance of Over Voltage Ride-Through (OVRT) 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 OVRT requirements include such installations, e.g. single-phase or 3-phase systems. 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 inverters numerical simulation and model validation.

General Information

Status
Published
Publication Date
21-Nov-2021
Current Stage
PPUB - Publication issued
Completion Date
22-Nov-2021
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IEC TS 63217
Edition 1.0 2021-11
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for over voltage
ride-through measurements
IEC TS 63217:2021-11(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 63217
Edition 1.0 2021-11
TECHNICAL
SPECIFICATION
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure for over voltage
ride-through measurements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-1051-2

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 63217:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms, definitions, symbols and abbreviated terms .......................................................... 7

3.1 Terms, definitions and symbols ............................................................................... 7

3.2 Abbreviated terms ................................................................................................. 10

4 Test circuit and equipment ............................................................................................. 10

4.1 General ................................................................................................................. 10

4.2 Test circuit ............................................................................................................ 10

4.3 Test equipment ..................................................................................................... 11

4.3.1 Measuring instruments................................................................................... 11

4.3.2 DC source ..................................................................................................... 11

4.3.3 Multi-tap transformer ..................................................................................... 12

4.3.4 Grid fault simulator ........................................................................................ 12

5 Test ............................................................................................................................... 14

5.1 Test protocol ......................................................................................................... 14

5.2 Test curve ............................................................................................................. 16

5.3 Test procedure ...................................................................................................... 16

5.3.1 Pre-test ......................................................................................................... 16

5.3.2 No-load test ................................................................................................... 16

5.3.3 Tolerance ...................................................................................................... 16

5.3.4 Load test ....................................................................................................... 17

6 Assessment criteria ....................................................................................................... 17

Annex A (informative) Determination of critical performance values in OVRT testing............ 18

A.1 General ................................................................................................................. 18

A.2 Ride-through time ................................................................................................. 18

A.3 Voltage swell ratio ................................................................................................ 18

A.4 Reactive current.................................................................................................... 19

A.5 Active power ......................................................................................................... 19

Annex B (informative) OVRT curve and criteria .................................................................... 20

B.1 General ................................................................................................................. 20

B.2 OVRT curve .......................................................................................................... 20

B.3 Test points ............................................................................................................ 20

B.4 Criteria .................................................................................................................. 21

Bibliography .......................................................................................................................... 22

Figure 1 – Testing circuit diagram ......................................................................................... 11

Figure 2 – RLC-series emulator for three-phase EUT ............................................................ 12

Figure 3 – RLC-series emulator for single-phase EUT ........................................................... 12

Figure 4 – Converter based emulator for three-phase EUT ................................................... 14

Figure 5 – Converter based emulator for single-phase EUT .................................................. 14

Figure 6 – OVRT curve example ........................................................................................... 16

---------------------- Page: 4 ----------------------
IEC TS 63217:2021 © IEC 2021 – 3 –

Figure 7 – Tolerance of voltage swell .................................................................................... 17

Figure A.1 – Critical performance values in OVRT testing ..................................................... 18

Figure B.1 – Typical curve of OVRT ...................................................................................... 20

Table 1 – Accuracy of measurements ................................................................................... 11

Table 2 – Test specification for OVRT (indicative) ................................................................. 15

---------------------- Page: 5 ----------------------
– 4 – IEC TS 63217:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR OVER VOLTAGE RIDE-THROUGH
MEASUREMENTS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC TS 63217 has been prepared by IEC technical committee 82: Solar photovoltaic energy

systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
82/1926/DTS 82/1960/RVDTS

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 Specification is English.

---------------------- Page: 6 ----------------------
IEC TS 63217:2021 © IEC 2021 – 5 –

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

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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,
• replaced by a revised edition, or
• amended.

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– 6 – IEC TS 63217:2021 © IEC 2021
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS –
TEST PROCEDURE FOR OVER VOLTAGE RIDE-THROUGH
MEASUREMENTS
1 Scope

This document provides a test procedure for evaluating the performance of Over Voltage

Ride-Through (OVRT) 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 OVRT requirements include such

installations, e.g. single-phase or 3-phase systems.

Fundamentally, the assessed OVRT 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

OVRT response to behave differently.

The measurement procedures are designed to be as non-site-specific as possible, so that

OVRT 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 inverters

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 61400-21-1:2019, Wind energy generation systems – Part 21-1: Measurement and
assessment of electrical characteristics – Wind turbines

IEC TS 61836:2016, Solar photovoltaic energy systems – Terms, definitions and symbols

IEC TS 63106-1:2020, Simulators used for testing of photovoltaic power conversion

equipment – Recommendations – Part 1: AC power simulators

IEC TS 63106-2:2022, Simulators used for testing of photovoltaic power conversion

equipment – Recommendations – Part 2: DC power simulators
---------------------- Page: 8 ----------------------
IEC TS 63217:2021 © IEC 2021 – 7 –
3 Terms, definitions, symbols and abbreviated terms

For the purposes of this document, the terms, definitions, symbols and abbreviated terms 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
3.1 Terms, definitions and symbols
3.1.1
over voltage ride-through
OVRT

capability of an inverter to continue generating power to connected utility grid during a limited

duration voltage swell (see 3.1.28) of grid voltage
3.1.2
utility grid
grid for which an electrical utility is responsible
[SOURCE: IEC TS 61836:2016, 3.3.29.2]
3.1.3
tap-changer

apparatus or accessory for usually automatically changing transformer taps to regulate

system voltage
3.1.4
inverter

electric energy converter that changes direct electric current to single-phase or polyphase

alternating currents
[SOURCE: IEC TS 61836:2016, 3.2.15]
3.1.5
equipment under test
EUT

equipment on which these tests are performed and refers to the utility-interconnected PV

inverter
3.1.6
EUT
access point of the EUT during the test
3.1.7
rated power of EUT
3.1.8
proportionality constant K
K-factor

setting parameters affecting OVRT behaviour of the EUT regarding reactive current injection

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– 8 – IEC TS 63217:2021 © IEC 2021
3.1.9
photovoltaic array

mechanical and electrical assembly of photovoltaic modules, photovoltaic panels or

photovoltaic sub-arrays and its support structure
[SOURCE: IEC TS 61836:2016, 3.3.59.1]
3.1.10
PV array simulator
simulator that has I-V characteristics equivalent to a PV array
[SOURCE: IEC TS 61836:2016, 3.5.3]
3.1.11
EUT
apparent short-circuit power at N
EUT
S = I × U ,
EUT sc N
I refers to short-circuit current at N during the no-load test
sc EUT
3.1.12
single-phase fault
single-phase grounded fault
3.1.13
two-phase fault
two-phase short circuit fault or two-phase grounded fault
3.1.14
reactive power compensation device
device that is used to improve voltage regulation of the utility grid
3.1.15
grid fault simulator

simulator that has the ability to simulate static and dynamic voltage characteristics of different

grid faults
3.1.16
over voltage fault

situation in which the amplitude of grid voltage is higher than normal working voltage range

3.1.17
AC main power port
point of connection of the AC grid to the EUT
3.1.18
DC main power port
point of connection of the DC power source to the EUT
3.1.19
voltage transformer

instrument transformer in which the secondary voltage in normal conditions of use, is

substantially proportional to the primary voltage and differs in phase from it by an angle which

is approximately zero for an appropriate direction of the connections
[SOURCE: IEC 60050-321:1986, 321-03-01]
---------------------- Page: 10 ----------------------
IEC TS 63217:2021 © IEC 2021 – 9 –
3.1.20
current transformer

instrument transformer in which the secondary current in normal conditions of use, is

substantially proportional to the primary current and differs in phase from it by an angle which

is approximately zero for an appropriate direction of the connections
[SOURCE: IEC 60050-321:1986, 321-02-01]
3.1.21
tap transformer

device employing the principle of mutual induction to obtain different turn ratio, automatically

changing transformer taps to regulate output voltage
3.1.22
short circuit

connection of comparatively low resistance accidentally or intentionally made between points

on a circuit between which the resistance is normally much greater
3.1.23
back-to-back converter

power electronics equipment that converts input AC power to a DC link power with stable

voltage or current, then converts the DC link power back to AC power
3.1.24
mechanical circuit breaker

mechanical switch that automatically interrupts the current of an overloaded electric circuit

3.1.25
step-up transformer

device employing the principle of mutual induction to obtain higher output voltage from low

input voltage
3.1.26
voltage swell ratio
3.1.27
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, connected

Note 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]
3.1.28
voltage swell

temporary increase of the voltage magnitude at a point in the electrical system above a

threshold
[SOURCE: IEC 61000-4-30:2015]
---------------------- Page: 11 ----------------------
– 10 – IEC TS 63217:2021 © IEC 2021
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
MP measurement point
MV middle voltage
OVRT over voltage ride through
PCC point of common coupling
PV photovoltaic
RLC resistor, inductor and capacitor
RMS root mean square
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 over voltage faults, including:
• Single-phase over voltage fault
• Two-phase over voltage fault
• Three-phase over voltage fault
NOTE Only single phase over voltage fault is suitable for
...

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