IEC TS 63106-2:2022

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.

General Information

• Status: Published
• Publication Date: 28-Mar-2022
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 6 - TC 82/WG 6
• Current Stage: PPUB - Publication issued
• Start Date: 29-Mar-2022
• Completion Date: 28-Apr-2022

Standards Content (Sample)

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
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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
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-1093-5

– 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

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

– 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

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
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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.

– 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
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contents. Users should therefore print this document using a colour printer.

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.

– 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

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

– 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
V
oc
open circuit voltage that appears at the output terminal of photovoltaic module or array under solar
irradiation
3.13
short circuit current
I
sc
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.

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 test. A DC power simulator is connected to the DC input power port. An AC power
simulator is connected to the AC output power port, with other optional impedance and load
equipment.
Figure 2 shows only the main power line connections to DC port, AC port in both sides. An earth
line may be shared between DC side and AC side devices.

– 12 – IEC TS 63106-2:2022 © IEC 2022

Figure 2 – Examples of fundamental setup of EUT test system
5.3 System configuration options
5.3.1 General
DC power simulators may consist of one or more of the following types of equipment. Other
approaches are possible depending on the test(s) under consideration.
As different tests have different power simulator needs, it may be necessary or optimal for a facility
to have more than one type of DC power simulator.
5.3.2 PV array
A PV array provides real-world irradiance variations, etc., which may be useful or necessary for
some types of tests. However, irradiance conditions may make it impractical for tests that need
stable, continuous and full capacity output power, so test feasibility and scheduling are subject to
time and weather conditions.
For module level or very small array level PCE, an indoor array with artificial lighting may be a
viable option.
In all cases where a real PV array is used, the response depends on the module technology
(crystalline, thin film, etc.) and cannot be changed.
A PV array is also used as an option for an evaluation of output voltage/current characteristics of
a PV array simulator or DC power supply, in case the performance of the PV array simulator or DC
power supply has to be compared to a real PV array for the test combined with PCE.

IEC TS 63106-2:202 © IEC 2022 – 13 –
5.3.3 PV array simulator
A PV array simulator is a power supply that has I-V curve characteristics resembling an actual PV
module array.
The I-V curve can be based on information from PV module manufacturers or could be specified
in the standards that the PCE is being tested to (e.g., IEC 62891 or EN 50530).
PV array simulators provide voltage, current and power with the characteristics of real PV modules
but without dependence on time and weather conditions.
They can be configured to simulate different irradiance levels and module technologies (crystalline,
thin film, etc.).
As some aspects of PCE functionality and performance may be critically dependent on, or
influenced by, the I-V curve, use of an PV array simulator may be necessary or preferred for certain
types of tests.
NOTE The I-V curve characteristics examples of crystalline and thin film PV modules used for the EUT testing are
indicated in IEC 62891 and EN 50530.
5.3.4 DC power supply
A DC power supply is a general-purpose AC to DC power converter with no capability for simulating
the I-V curve of a PV module. Such power supplies typically operate their output in constant voltage
or constant current mode and offer stable control over DC voltage and the available current and
power.
However, this square-shaped I-V curve represents a unity fill-factor, which does not occur in real
PV arrays.
The extent to which a DC power supply will work for certain type tests depends on whether or not
the test results rely on or can be affected by the I-V curve of the source. Also, the EUT’s MPPT
control software may not find a stable operating point when the source has a rectangular I-V curve.
The issue may be rectified by applying a series resistance between the DC power supply and the
EUT, creating a roll-off curve and MPP that is easier for the EUT’s control software to locate.
When applying a series resistance, the maximum DC voltage applied to EUT with zero-current
output, should be known and should not exceed the maximum rated voltage of EUT.
However, when the EUT’s power capacity is at MW-scale, the power consumption and heat
dissipation due to series resistance may be prohibitively large.
6 General recommendations for DC power simulator
6.1 General
In this clause, general recommendations for DC power simulators are indicated.
The AC power input frequency and voltage requirements for DC power simulators are specified by
the manufacturer considering the DC output voltage/current accuracy, including dynamic
performance.
– 14 – IEC TS 63106-2:2022 © IEC 2022
6.2 DC output voltage accuracy and ripple
The simulator output voltage accuracy should comply with the accuracy requirements of the
standards in which the tests being performed are specified, and should be adequate to allow proper
and repeatable testing.
This may require attention to accuracy under static conditions, across line and load variations, and
possibly under load ramp or step change conditions.
DC output voltage ripple of DC power simulators should be taken into consideration if required to
comply with standards in which the tests being performed are specified, or for proper and
repeatable testing.
While a real PV array inherently creates ripple-free DC voltage for static operation point of V-I
curve, the connected equipment such as inverters may create significant voltage ripple due to their
topology and/or inherent current ripple. Correct testing may or may not require attention to voltage
ripple. See also 6.3.1.4.
Standards specifying ripple limits for testing of PV equipment should consider this carefully to
avoid unrealistic and onerous requirements.
6.3 I-V curve stability for EUT testing
6.3.1 General
6.3.1.1 Overview
This subclause discusses basic recommendations for the stability of the I-V curve characteristics
of the output of a PV array simulator, which may be affected by the EUT operational state and
state changes, by the PV array simulator’s AC input conditions, and by other factors.
6.3.1.2 Characteristic and performance of PV array simulators for EUT tests
The EUT DC current and voltage fluctuate during MPPT or other characteristics of the PCE
operation including dynamic power change in AC side fluctuation test. The PV array simulator’s I-
V curve is expected to keep stable to simulate the actual photovoltaic array performance.
Recommended current and voltage accuracies for test performance are addressed in Annex A
(informative) DC I-V curve accuracy against MPPT control.
Other recommendations such as static and dynamic characteristics and stability of PV array
simulators are referred to IEC 62891.
6.3.1.3 MPPT power survey oscillation
The DC current from the PV array to the PCE fluctuates due to the maximum power point tracking
control of the PCE. On the I-V curve, the DC voltage induced from PV array to PCE fluctuates in
the opposite direction of the DC current variation.
The MPPT survey speed and current change step width depends on the design of the EUT control.
The PV array simulator output should maintain accurate tracking of the programmed I-V curve
during the rapid load current changes demanded by the MPPT survey of the EUT.
See Annex A.
IEC TS 63106-2:202 © IEC 2022 – 15 –
6.3.1.4 Utility frequency ripple voltage/current
In some PCE topologies, the DC input to the PCE has a ripple superimposed on it based on the
AC line frequency (e.g. twice the line frequency for single phase inverters).
This ripple voltage can be quite large from the PV array to earth (common mode), but there may
also be significant line to line ripple.
The utility-frequency ripple does not appear during the stable operation of three-phase PCE,
because the summation of the balanced three phase power with the time keeps constant, whereas
the single-phase power derived by multiplication of instantaneous voltage and current with the time
fluctuates in twice the utility frequency.
In case of line to line short circuit failure protection or under voltage ride-through test in three
phase system, the AC voltage waveform shifts to single phase operation and there appears the
twice the utility frequency in DC side of the PCE. The PV array simulator output should maintain
accurate tracking of the programmed I-V curve with this ripple voltage applied by the PCE.
See Annex B.
6.3.1.5 Quick power change in the UVRT test
During the UVRT test, AC output power suddenly reduces and then increases due to AC voltage
test conditions.
In that situation, the DC side I-V characteristics should be stable as DC current reduces and DC
voltage increases towards the open circuit voltage along the I-V curve.
The voltage increase rate and set-back rate for UVRT test depends on AC voltage change rate in
the test.
UVRT test procedure is indicated in IEC TS 62910.
See Annex C.
6.3.2 DC irradiance change rate
6.3.2.1 Slow irradiance rising during sunrise
For the test of EUT automatic start in the morning, irradiance rising speed is controlled as slow as
the real-world behavior.
In the early morning, the open circuit voltage of a PV array rises rapidly as irradiance increases.
Depending on the design of residential use or small-sized EUTs, control circuit power is supplied
from the PV array before the interconnection to the utility grid.
Detecting that the DC input voltage rises up to the design threshold of the EUT, the control circuit
begins to operate.
At that moment, the I-V curve voltage rapidly reduces because the irradiance is not enough to
generate and deliver the sufficient EUT control power to make the EUT stand-by.
This causes a number of starts and stops in the PCE control because the I-V curve is unstable
with respect to available current. For tests of the start-up operation characteristics of the EUT,
certain resolution and accuracy of the output voltage for low irradiance is recommended.

– 16 – IEC TS 63106-2:2022 © IEC 2022
For the operation in this area of I-V curve, the PV array simulator should have sufficient resolution
with current stability for quick voltage change to replicate these current/voltage characteristics.
Typically, large EUT use their circuit control power from the utility all the time. In that case, the
automatic start sequence is activated by detecting that the DC input voltage is risen-up to the
design threshold of the EUT, to begin feeding gate signals from the control system to switching
devices.
In that case, the start and stop operation cycle does not occur, but still, open voltage rise-up speed
in the morning should be simulated by the PV array simulator.
For testing the compliance accuracy in the range of morning startup and evening stop down period,
testing condition and sequence are indicated in EN 50530.
As a testing procedure reference for rate of change of irradiance, EN 50530 specifies 0,1 W/m ･s
both for ramp up and ramp down for start-up and shut down sequence measurement as the test
pattern.
See Annex D.
6.3.2.2 Slow irradiance falling during sunset
The open circuit voltage of the PV array decreases rapidly as irradiance falls in the sunset, when
the MPP part of the I-V curve is under the voltage axis. It sometimes causes a repetition of start
and stop in the PCE control, because the I-V curve is unstable to the current rise.
For the testing of PCE stable operation to shut down for the sunset time, irradiance parameter
decreasing sequence is performed in the reverse way for the morning duration,
In the same manner, the PV array simulator should have sufficient resolution with current stability
for quick voltage change to replicate these current/voltage characteristics, in the testing condition
of low irradiance parameter.
See Annex D.
6.3.2.3 Rapid irradiance fluctuation due to cloud cover
Irradiance may change rapidly due to cloud cover or cloud-edge enhancement events. This causes
correspondingly rapid fluctuations in the DC voltage and current from the PV array.
The EUT is expected to operate in that situation and so the DC power simulator should be able to
change the available power to the EUT at similar or faster rates if such conditions are a required
part of a test. For example, for dynamic MPPT testing, IEC 62891 requires the MPP to be changed
at rates of up to 100 W/m per second.
The largest irradiance change rate is estimated to be 0 % to 100 % in 2 s which is sufficiently fast
for known operating conditions and locations. See Annex E.
For transitional irradiance change speed, some numbers are given as examples. Further
measurements for quicker irradiation change may be used as a worst-case scenario.
6.4 DC power simulator performance and characteristics for utility interaction tests
The characteristics and performance of DC power simulators that are important for the correct and
effective application of testing of PCE depend on the specifics of the test being considered.

IEC TS 63106-2:202 © IEC 2022 – 17 –
Recommendations for desired characteristics are indicated in Table 1 through Table 22 for the
same utility interaction tests that are covered in the similar tables in IEC TS 63106-1 for AC
simulators. Tests for which there is no corresponding table for AC simulators in IEC TS 63106-1
are covered in 6.5
The characteristics recommended in Table 1 through Table 22 should be maintained over the full
range of conditions as applicable for the test specification.
NOTE Abbreviations indicated in Table 1 through Table 22 are: P for active power, Q for reactive power, S for apparent
power, PF for power factor, OV for over voltage, UV for under voltage, OF for over frequency, UF for under frequency,
Iq for reactive current and ROCOF for rate of change of frequency.
Table 1 – Grid qualification/Requalification –
In-range AC voltage before connection/reconnection
Short description of test Before starting the test, the DC power simulator operates at the set open
circuit voltage point without current. After increasing/decreasing AC
voltage and crossing the AC voltage threshold for the interconnection,
EUT starts generation and DC current rises relevant to the output power
of the EUT. Typically, not required to be done at full power and often
signal injection methods are allowed.
Important DC power simulator Important aspects of the simulator attribute
attributes for this specific test
Power Simulator power may be signal level, or a small percentage of EUT rated
output, allowing a range of techniques.
Usability of DC power simulator Usability Capabilities and Drawbacks
types benefits
PV array Partial EUT starting and Testing time is limited by
operating behaviour on the weather, with
DC side is real and daytime-stable
reliable. irradiation condition.
I-V characteristic is
limited depending on the
PV module type and
array circu
...