Simulators used for testing of photovoltaic power conversion equipment - Recommendations - Part 2: DC power simulators

IEC TS 63106-2:2022 provides recommendations for Low Voltage (LV) DC power simulators used for testing photovoltaic (PV) power conversion equipment (PCE) to utility interconnection or PV performance standards. This document primarily addresses DC power simulators used for testing of grid-interactive PCE, also referred to as grid-connected power converters (GCPCs). It also addresses some uses of DC power simulators for testing stand-alone and multi-mode PCEs.

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Status
Published
Publication Date
28-Mar-2022
Current Stage
PPUB - Publication issued
Completion Date
29-Mar-2022
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IEC TS 63106-2:2022 - Simulators used for testing of photovoltaic power conversion equipment - Recommendations - Part 2: DC power simulators
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IEC TS 63106-2
Edition 1.0 2022-03
TECHNICAL
SPECIFICATION
colour
inside
Simulators used for testing of photovoltaic power conversion equipment –
Recommendations –
Part 2: DC power simulators
IEC TS 63106-2:2022-03(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 63106-2
Edition 1.0 2022-03
TECHNICAL
SPECIFICATION
colour
inside
Simulators used for testing of photovoltaic power conversion equipment –
Recommendations –
Part 2: DC power simulators
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-1093-5

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 63106-2:2022 © IEC 2022
CONTENTS

FOREWORD .......................................................................................................................... 5

INTRODUCTION .................................................................................................................... 7

1 Scope ............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 9

4 PCE types with respect to DC voltage levels ................................................................. 10

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

4.2 Module level PCE ................................................................................................. 11

4.3 String level PCE ................................................................................................... 11

4.4 Central PCE ......................................................................................................... 11

5 Test setup for utility interactive inverters ....................................................................... 11

5.1 General ................................................................................................................ 11

5.2 Test setup examples ............................................................................................ 11

5.3 System configuration options ................................................................................ 12

5.3.1 General ......................................................................................................... 12

5.3.2 PV array ........................................................................................................ 12

5.3.3 PV array simulator......................................................................................... 13

5.3.4 DC power supply ........................................................................................... 13

6 General recommendations for DC power simulator ........................................................ 13

6.1 General ................................................................................................................ 13

6.2 DC output voltage accuracy and ripple ................................................................. 14

6.3 I-V curve stability for EUT testing ......................................................................... 14

6.3.1 General ......................................................................................................... 14

6.3.2 DC irradiance change rate ............................................................................. 15

6.4 DC power simulator performance and characteristics for utility interaction tests ... 16

6.5 Additional tests conducted with DC power simulators ........................................... 34

6.5.1 General ......................................................................................................... 34

6.5.2 PCE operational stability with sudden irradiance changes (due to

movement of sun between clouds) ................................................................ 35

6.5.3 Automatic start and stop operation with gradual irradiance changes

(representing morning and evening conditions) ............................................. 36

6.5.4 PCE DC to AC power conversion efficiency measurement ............................. 36

6.5.5 PCE maximum power point tracking efficiency measurement ........................ 36

6.5.6 PCE total power conversion efficiency measurement ..................................... 37

6.6 Avoidance measures of transient impact to EUTs ................................................. 37

Annex A (informative) DC I-V curve dynamic accuracy against MPPT control ...................... 38

A.1 General ................................................................................................................ 38

A.2 Example of DC I-V curve stability for MPPT properties ......................................... 38

A.2.1 MPPT control ................................................................................................ 38

A.2.2 Recommended stability of operation on the I-V curve .................................... 39

A.2.3 Recommended I-V curve resolution ............................................................... 39

A.2.4 Use of DC power supply as an input of EUT .................................................. 39

Annex B (informative) DC power simulator stability against utility- frequency ripple

voltage/current ..................................................................................................................... 41

B.1 General ................................................................................................................ 41

B.2 Example of twice the utility- frequency ripple voltage/current ................................ 41

B.2.1 Twice the utility frequency ripple voltage/current ........................................... 41

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IEC TS 63106-2:202 © IEC 2022 – 3 –

B.2.2 Stability of I-V curve for the DC ripple ........................................................... 42

Annex C (informative) PV array simulator I-V curve stability against quick power change

in UVRT test ......................................................................................................................... 44

C.1 General ................................................................................................................ 44

C.2 DC voltage/current shift by withdrawing power change in UVRT test .................... 44

Annex D (informative) DC I-V curve stability against low irradiance at sunrise and sunset ... 47

D.1 General ................................................................................................................ 47

D.2 Example of a DC I-V curve stability against slow irradiance change rate in the

morning and evening – I-V curve with low irradiance periods and EUT input

voltage/current transition ...................................................................................... 47

Annex E (informative) DC I-V curve behaviour in rapidly varying irradiance conditions ........ 49

E.1 General ................................................................................................................ 49

E.2 I-V curve response to varying irradiance ............................................................... 49

E.2.1 Irradiance sudden change on I-V characteristics of the PV array (an

example) ....................................................................................................... 49

E.2.2 Recommendation of irradiance quick change rate for test of the EUT by PV

array simulator .............................................................................................. 49

Bibliography ......................................................................................................................... 52

Figure 1 – Examples of ports .................................................................................................. 9

Figure 2 – Examples of fundamental setup of EUT test system ............................................. 12

Figure A.1 – Voltage and current swing by MPPT control on I-V curve around MPP.............. 38

Figure A.2 – Current and voltage swing by MPPT control on I-V curve below MPP ............... 39

Figure A.3 – Current and voltage swing by MPPT control on I-V characteristic curve of

DC power supply .................................................................................................................. 40

Figure B.1 – DC current and voltage ripple on single-phase GCPC ....................................... 41

Figure B.2 – DC current and voltage ripple on three-phase GCPC with UVRT test ................ 42

Figure B.3 – DC ripple I-V swing on I-V curve of PV array .................................................... 43

Figure C.1 – DC input voltage/current transition on zero-voltage ride through test – AC

voltage sudden reduction ..................................................................................................... 45

Figure C.2 – DC input voltage/current transition on zero-voltage ride through test – AC

voltage sudden recovery ...................................................................................................... 46

Figure C.3 – DC input voltage/current transition on UVRT test – AC voltage sudden

decrease .............................................................................................................................. 46

Figure D.1 – DC input voltage/current transition area in the morning and evening ................ 47

Figure D.2 – DC input voltage transition pattern example in the morning .............................. 48

Figure E.1 – DC input voltage/current quick transition and MPPT ......................................... 50

Figure E.2 – Irradiance quick change example ..................................................................... 50

Figure E.3 – Irradiation change rate for PV array and wind orientation ................................. 51

Table 1 – Grid qualification/Requalification – In-range AC voltage before

connection/reconnection ....................................................................................................... 17

Table 2 – Grid qualification/Requalification – In-range AC frequency before

connection/reconnection ....................................................................................................... 18

Table 3 – Power capability: Nameplate P, Q, S under normal and near-normal grid

conditions ............................................................................................................................. 19

Table 4 – Power capability: Limitation of P/Q/S/PF by setpoint ............................................. 20

Table 5 – Power capability: Ramp rate or soft start time-developing magnitude by set rate . 21

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– 4 – IEC TS 63106-2:2022 © IEC 2022

Table 6 – Grid protection tests – AC over-voltage (OV) and under-voltage (UV) trip tests ..... 22

Table 7 – Grid protection tests: OF/UF trips ......................................................................... 22

Table 8 – Grid protection tests: Anti-islanding ...................................................................... 23

Table 9 – Grid protection tests: Rate of Change of Frequency (ROCOF) trips ....................... 24

Table 10 – Grid protection tests: Open phase ....................................................................... 24

Table 11 – Power quality tests: Current harmonics, inter-harmonics, THDi ........................... 25

Table 12 – Power quality tests: Flicker (continuous) ............................................................. 26

Table 13 – Power quality tests: Current inrush (at connection switch close) ......................... 27

Table 14 – Power quality tests: AC output current imbalance ............................................... 27

Table 15 – Power quality tests: Transient over-voltage (TrOV) on load dump ....................... 28

Table 16 – Grid support tests: UV/OV ride-through with/without Iq injection .......................... 29

Table 17 – Grid support tests: UF/OF ride-through ............................................................... 30

Table 18 – Grid support tests: ROCOF ride-through ............................................................. 30

Table 19 – Grid support tests: Phase-jump ride-through ....................................................... 31

Table 20 – Grid support tests: P (f), PF (P, V), Q (V), P (V) .................................................. 32

Table 21 – External command response tests: Magnitude accuracy for P/Q/S/PF by

setpoint ................................................................................................................................ 33

Table 22 – External command response tests: Response to external setpoint changes

(response time, settling time test) ......................................................................................... 34

Table 23 – Test items and DC power simulators application for PCE .................................... 35

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IEC TS 63106-2:202 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SIMULATORS USED FOR TESTING OF PHOTOVOLTAIC POWER
CONVERSION EQUIPMENT – RECOMMENDATIONS –
Part 2: DC power simulators
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-

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

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

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

IEC TS 63106-2 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
82/1954/DTS 82/1999/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: 7 ----------------------
– 6 – IEC TS 63106-2:2022 © IEC 2022

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 described

in greater detail at www.iec.ch/standardsdev/publications.

A list of all parts in the IEC TS 63106 series, published under the general title Simulators used for

testing of photovoltaic power conversion equipment – Recommendations , can be found on the

IEC web site.

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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it

contains colours which are considered to be useful for the correct understanding of its

contents. Users should therefore print this document using a colour printer.
---------------------- Page: 8 ----------------------
IEC TS 63106-2:202 © IEC 2022 – 7 –
INTRODUCTION

The objective of this document is to establish terminology, create a framework for, and provide

guidance regarding the electrical performance of DC power simulators used to test photovoltaic

(PV) power conversion equipment (PCE) for compliance with grid interconnection or PV

performance standards.

Along with IEC TS 63106-1, it provides guidance for the selection or development of power

simulators used within a test and evaluation system for PV PCEs.

Testing laboratories are responsible for selecting the appropriate test items and procedures as

well as defining the required performance for adequate evaluation of utility interactive PV PCEs,

considering utility power requirements, local codes and regulations.

It is intended for this document to be used in conjunction with parallel PCE standards developed

for specific performance or grid-interaction requirements.
---------------------- Page: 9 ----------------------
– 8 – IEC TS 63106-2:2022 © IEC 2022
SIMULATORS USED FOR TESTING OF PHOTOVOLTAIC POWER
CONVERSION EQUIPMENT – RECOMMENDATIONS –
Part 2: DC power simulators
1 Scope

The purpose of this part of IEC TS 63106 is to provide recommendations for Low Voltage (LV) DC

power simulators used for testing photovoltaic (PV) power conversion equipment (PCE) to utility

interconnection or PV performance standards.
NOTE Low Voltage refers to DC voltage 1 500 V and less.

In this document, the term “DC power simulator” refers to any source that is used during testing to

provide DC power to the Equipment Under Test (EUT). That includes, but is not limited to, PV

array simulators designed to simulate the DC output I-V curve of a photovoltaic array operating in

real-world conditions.

This document primarily addresses DC power simulators used for testing of grid-interactive PCE,

also referred to as grid-connected power converters (GCPCs). It also addresses some uses of DC

power simulators for testing stand-alone and multi-mode PCEs.

There are many types of tests that can be conducted by utilizing a DC power simulator. Certain

tests require the use of a PV array or PV array simulator, such as measurements of the PCE’s PV

input static and dynamic characteristics related to maximum power point tracking, while other tests

may be appropriate to conduct with a static DC power supply. Test requirements and procedures

are specified in IEC standards and local utility grid requirements, selected by the system integrator,

PCE manufacturer, network operator, utility, or third-party inspector.
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 61683, Photovoltaic systems – Power conditioners – Procedure for measuring efficiency

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

IEC 62116, Utility-interconnected photovoltaic inverters – Test procedure of islanding prevention

measures

IEC 62891, Maximum power point tracking efficiency of grid connected photovoltaic inverters

IEC TS 62910:2020, Utility-interconnected photovoltaic inverters – Test procedure for under

voltage ride-through measurements

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

Recommendations – Part 1: AC power simulators
EN 50530, Overall efficiency of grid connected photovoltaic inverters
---------------------- Page: 10 ----------------------
IEC TS 63106-2:202 © IEC 2022 – 9 –
3 Terms and definitions

For the purposes of this document, the terms and definitions given 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
DC power simulator

system or device able to source and/or absorb DC power, for use in testing of PCE

Note 1 to entry: In this document, DC power simulator is the general term including PV array, conventional DC power

supply or PV array simulator.
3.2
PV array simulator

type of DC power simulator that implements the key characteristics of the I-V curve of real

photovoltaic module types, having a maximum power point, operating voltage, and available

current that vary with load and irradiance
3.3
power conversion equipment
PCE

electrical device converting one kind of electrical power from a voltage or current source into

another kind of electrical power with respect to voltage, current and frequency
[SOURCE: IEC 62109-1:2010, 3.66]
3.4
port

terminal or set of terminals where the PCE connects to conductors of an external power, control,

or communications system
Note 1 to entry: See Figure 1 for examples of ports.
Figure 1 – Examples of ports
3.5
equipment under test
EUT
PCE that is tested by connecting and supplying DC and AC power to each port
---------------------- Page: 11 ----------------------
– 10 – IEC TS 63106-2:2022 © IEC 2022
3.6
AC output power port

port used to connect to a public low voltage AC mains power distribution network or other low

voltage AC mains installation
3.7
DC input power port

port used to connect the PCE to the DC power simulator during testing, or a PV array or other DC

source in the installation
3.8
type test
conformity test performed on one or more items representative of the production
[SOURCE: IEC 60050-151:2001, 151-16-16]
3.9
maximum power point
MPP

operational voltage and current point on the output characteristic of photovoltaic module or array

that delivers the largest output power depending on solar irradiance and temperature

3.10
maximum power point tracking
MPPT

PCE control function to survey the maximum input DC power point on the characteristic of

photovoltaic modules power generation
3.11
under voltage ride through
UVRT

PCE operational durability for the situation of low voltage supply by the AC power system

3.12
open circuit voltage

open circuit voltage that appears at the output terminal of photovoltaic module or array under solar

irradiation
3.13
short circuit current

short circuit current that appears at the output terminal of photovoltaic module or array under solar

irradiation
4 PCE types with respect to DC voltage levels
4.1 General
PV PCE may be connected to PV modules or arrays in a variety of ways.

The maximum limit of the operating DC voltage range of PV PCE takes into account the absolute

maximum value of the open circuit voltage of the array under any condition (irradiance,

temperature, etc.).

Therefore, an upper limit of 1 500 V for the DC voltage range of a PCE test system is sufficient.

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IEC TS 63106-2:202 © IEC 2022 – 11 –
4.2 Module level PCE

Module level PCE is connected to a single PV module with operating voltages typically in the DC

voltage 65 V to 100 V range.

However, some DC to DC converters are used in series connection, so it may be necessary for

the DC power simulator to be able to superimpose the system voltage (e.g. DC 1 000 V), with

respect to earth, depending on the test purpose.
4.3 String level PCE

String level PCE is connected to series strings of PV modules, with operating and system voltages

typically from DC voltage 600 V to 1 500 V maximum.
4.4 Central PCE

Central PCE is connected to a large number of series strings of PV modules in parallel, with

operating and system voltages typically from DC voltage 600 V to 1 500 V maximum.

5 Test setup for utility interactive inverters
5.1 General

In order to realize valid and reproducible testing, the DC power source should be appropriate for

the test being performed. This may mean utilizing an actual PV array, a conventional DC power

supply, or a PV array simulator depending on the needs of the specific test under consideration.

In order to realize valid and reproducible testing, the AC power source should also be appropriate

for the test being performed. Recommendations for AC power simulators are addressed in

IEC TS 63106-1.
5.2 Test setup examples

Figure 2 illustrates basic configuration examples for the EUT test system. Here, EUT is the PV

PCE under tes
...

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