IEC 62116:2014

Utility-interconnected photovoltaic inverters - Test procedure of islanding prevention measures

IEC 62116:2014 provides a test procedure to evaluate the performance of islanding prevention measures used with utility-interconnected PV systems. This standard describes a guideline for testing the performance of automatic islanding prevention measures installed in or with single or multi-phase utility interactive PV inverters connected to the utility grid. The test procedure and criteria described are minimum requirements that will allow repeatability. Major changes with respect to the previous edition concern the DC power source and test conditions.

Onduleurs photovoltaïques interconnectés au réseau public - Procédure d'essai des mesures de prévention contre l'îlotage

L'IEC 62116:2014 fournit une méthode d'essai pour évaluer la performance des mesures de prévention contre l'îlotage utilisées avec des systèmes PV interconnectés au réseau public. Cette norme décrit des lignes directrices pour les essais de performance des mesures de prévention contre l'îlotage automatique installées dans ou avec des onduleurs PV interactifs avec le réseau public monophasés ou multiphasés, connectés au réseau public d'électricité. La procédure et les critères d'essai décrits sont les exigences minimales qui permettent la répétabilité. Les principales modifications par rapport à l'édition précédente concernent la source d'énergie en courant continu et les conditions d'essai.

General Information

• Status: Published
• Publication Date: 25-Feb-2014
• 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: 26-Feb-2014
• Completion Date: 31-Mar-2014

Relations

• Revises: IEC 62116:2008 - Test procedure of islanding prevention measures for utility-interconnected photovoltaic inverters
• Effective Date: 05-Sep-2023

Overview

IEC 62116:2014 is an international standard developed by the International Electrotechnical Commission (IEC) that sets forth the test procedure for islanding prevention measures in utility-interconnected photovoltaic (PV) inverters. Its primary purpose is to ensure the reliability and safety of PV inverter systems connected to the utility grid by verifying their ability to detect and prevent islanding conditions. Islanding refers to a scenario where a portion of the electrical grid, including distributed generation such as PV systems and local loads, becomes electrically isolated from the utility but continues to be energized by the PV system. This can be hazardous for utility personnel and equipment, hence the necessity for stringent detection and prevention standards.

IEC 62116:2014 provides a well-defined, reproducible test methodology and performance criteria for automatic islanding prevention mechanisms installed in single or multi-phase utility-interactive PV inverters. This second edition includes important updates related to DC power sources and testing conditions to enhance testing accuracy and system safety.

Key Topics

• Islanding Prevention: The standard focuses on automatic islanding detection and prevention measures that ensure the inverter disconnects or ceases to energize the grid promptly when utility power is lost.
• Test Circuit and Equipment: Detailed configurations for testing circuits, including DC power sources, AC power sources, and AC loads, are provided to simulate real-world conditions.
• Test Procedure: Step-by-step guidelines enable consistent evaluation of islanding detection in various load and generating conditions.
• Pass/Fail Criteria: Minimum requirements define acceptable inverter performance to ensure compliance.
• Load Imbalance Testing: Procedures account for real and reactive load variability to assess islanding detection robustness.
• Documentation Requirements: Guidelines ensure manufacturers provide comprehensive test data and inverter specifications.
• Updates from Previous Edition: Enhanced definitions of power input parameters, adjusted input voltage reference levels, and clarified test condition criteria improve testing accuracy.

Applications

IEC 62116:2014 is critical for manufacturers, testing laboratories, certification bodies, and utility companies involved in the design, implementation, verification, and deployment of grid-connected photovoltaic inverters. The standard ensures:

• Safety Compliance: Helps prevent hazardous islanding events on the distribution grid, protecting utility workers and the public.
• Regulatory Approval: Serves as a benchmark for national and international compliance related to photovoltaic inverter interconnection standards.
• Product Quality Assurance: Assists manufacturers in validating inverter anti-islanding functions, enhancing product reliability and customer confidence.
• Grid Stability: Contributes to maintaining power quality and stability by ensuring PV systems disconnect safely during outages or fault conditions.
• Integration with Energy Storage: Applicable when PV inverters operate with DC sources including battery storage, supporting hybrid renewable energy systems.

Related Standards

• IEC 61727 - Photovoltaic (PV) systems - Characteristics of the utility interface: Complementary guidelines for electrical and functional requirements for PV system interfaces.
• IEEE 1547 - Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces: Provides broader grid interconnection criteria relevant to all distributed generation systems.
• UL 1741 - Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources: Addresses product safety and performance in North America.
• IEC 60038 - Standard Voltages: Defines reference voltages applicable in testing and grid interface applications.

---

By adhering to IEC 62116:2014, stakeholders enhance the safety, reliability, and efficiency of utility-connected photovoltaic systems, fostering wider adoption of solar energy aligned with grid operational requirements. This standard is vital for ensuring smooth, secure integration of renewable energy into the electrical distribution network worldwide.

Standards Content (Sample)

IEC 62116 ®
Edition 2.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure of islanding
prevention measures
Onduleurs photovoltaïques interconnectés au réseau public – Procédure d’essai
des mesures de prévention contre l’îlotage

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IEC 62116 ®
Edition 2.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Utility-interconnected photovoltaic inverters – Test procedure of islanding

prevention measures
Onduleurs photovoltaïques interconnectés au réseau public – Procédure

d’essai des mesures de prévention contre l’îlotage

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX U
ICS 27.160 ISBN 978-2-8322-1442-8

– 2 – IEC 62116:2014 © IEC 2014
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Testing circuit . 9
5 Testing equipment . 11
5.1 Measuring instruments . 11
5.2 DC power source . 11
5.2.1 General . 11
5.2.2 PV array simulator . 12
5.2.3 Current and voltage limited DC power supply with series
resistance . 12
5.2.4 PV array . 12
5.3 AC power source . 13
5.4 AC loads . 13
6 Test for single or multi-phase inverter . 13
6.1 Test procedure . 13
6.2 Pass/fail criteria . 17
7 Documentation . 17
Annex A (informative) Islanding as it applies to PV systems . 20
A.1 General . 20
A.2 Impact of distortion on islanding . 21
Annex B (informative) Test for independent islanding detection device (relay) . 22
B.1 General . 22
B.2 Testing circuit . 22
B.3 Testing equipment . 22
B.3.1 General . 22
B.3.2 AC input source . 22
B.4 Testing procedure . 23
B.5 Documentation . 23
Annex C (informative) Gate blocking signal . 24
C.1 General . 24
C.2 Gate blocking signal used in photovoltaic systems . 24
C.3 Monitoring the gate blocking signal . 24
Bibliography . 25

Figure 1 – Test circuit for islanding detection function in a power conditioner (inverter) . 11
Figure B.1 – Test circuit for independent islanding detection device (relay) . 22

Table 1 – Parameters to be measured in real time . 10
Table 2 – Specification of array simulator (test conditions). 12
Table 3 – PV array test conditions . 13
Table 4 – AC power source requirements . 13
Table 5 – Test conditions . 14

Table 6 – Load imbalance (real, reactive load) for test condition A (EUT output =
100 %) . 16
Table 7 – Load imbalance (reactive load) for test condition B (EUT output = 50 % to
66 %) and test condition C (EUT output = 25 % to 33 %) . 16
Table 8 – Specification of the EUT provided by the manufacturer (example) . 17
Table 9 – List of tested condition and run on time (example) . 18
Table 10 – Specification of testing equipment (example) . 19

– 4 – IEC 62116:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS – TEST
PROCEDURE OF ISLANDING PREVENTION MEASURES

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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.
International Standard IEC 62116 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
This second edition cancels and replaces the first edition issued in 2008 and constitutes a
technical revision.
The main technical changes with regard to the previous edition are as follows:

Previous edition Present edition
Clause
3.7
5.1
5.4
6.1 b)
6.1 d)
Real power Active power
6.1 e)
6.1 g)
Table 1
Table 6
Table 7
Table 9
A PV array or PV array simulator (preferred) A DC power source, such as a PV array
may be used. simulator, a PV array, or a current and voltage
If the EUT can operate in utility-interconnected limited DC power supply with series resistance
mode from a storage battery, a DC power may be used.
source may be used in lieu of a battery as long If the EUT can operate in utility-interconnected
5.2
as the DC power source is not the limiting mode from a storage battery, a DC power
device as far as the maximum EUT input source may be used in lieu of a battery as long
current is concerned. as the DC power source shall not be the
limiting device as far as the maximum EUT
input current is concerned.
EUT input voltage 90 % EUT input voltage 75 %
EUT input voltage 10 % EUT input voltage 20 %
Table 5
EUT Trip Settings Manufacturer specified Voltage and frequency trip settings according
voltage and frequency trip settings to National standards and/or local code
Tables 6 &
Percent change in real load, reactive load from Percent change in active load, reactive load
nominal from nominal output power
(Heading)
The text of this standard is based on the following documents:
FDIS Report on voting
82/813/FDIS 82/827/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication 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.
– 6 – IEC 62116:2014 © IEC 2014
INTRODUCTION
Islanding is a condition in which a portion of an electric power grid, containing both load and
generation, is isolated from the remainder of the electric power grid. This situation is one
which electric power providers (utilities) regularly contend with. When an island is created
purposely by the controlling utility – to isolate large sections of the utility grid, for example – it
is called an intentional island. Conversely, an unintentional island can be created when a
segment of the utility grid containing only customer-owned generation and load is isolated
from the utility control.
Normally, the customer-owned generation is required to sense the absence of utility-
controlled generation and cease energizing the grid. However, when the generation and load
within the segment are well balanced prior to the isolation event, the utility is providing little
power to the grid segment, thus making it difficult to detect when the isolation occurs.
Damage can occur to customer equipment if the generation in the island, no longer under
utility control, operates outside of normal voltage and frequency conditions. Customer and
utility equipment can be damaged if the main grid recloses into the island out of
synchronization. Energized lines within the island present a shock hazard to unsuspecting
utility lineworkers who think the lines are dead.
The PV industry has pioneered the development of islanding detection and prevention
measures. To satisfy the concerns of electric power providers, commercially-available utility-
interconnected PV inverters have implemented a variety of islanding detection and prevention
(also called anti-islanding) techniques. The industry has also developed a test procedure to
demonstrate the efficacy of these anti-islanding techniques; that procedure is the subject of
this document.
This standard provides a consensus test procedure to evaluate the efficacy of islanding
prevention measures used by the power conditioner of utility-interconnected PV systems.
Note that while this document specifically addresses inverters for photovoltaic systems, with
some modifications the setup and procedure may also be used to evaluate inverters used with
other generation sources or to evaluate separate anti-islanding devices intended for use in
conjunction with PV inverters or other generation sources acting as or supplementing the anti-
islanding feature of those sources.
Inverters and other devices meeting the requirements of this document can be considered
non-islanding, meaning that under reasonable conditions, the device will detect island
conditions and cease to energize the public electric power grid.

UTILITY-INTERCONNECTED PHOTOVOLTAIC INVERTERS – TEST
PROCEDURE OF ISLANDING PREVENTION MEASURES

1 Scope
The purpose of this International Standard is to provide a test procedure to evaluate the
performance of islanding prevention measures used with utility-interconnected PV systems.
This standard describes a guideline for testing the performance of automatic islanding
prevention measures installed in or with single or multi-phase utility interactive PV inverters
connected to the utility grid. The test procedure and criteria described are minimum
requirements that will allow repeatability. Additional requirements or more stringent criteria
may be specified if demonstrable risk can be shown. Inverters and other devices meeting the
requirements of this standard are considered non-islanding as defined in IEC 61727.
This standard may be applied to other types of utility-interconnected systems (e.g. inverter-
based microturbine and fuel cells, induction and synchronous machines). However, technical
review may be necessary for other than inverter-based PV systems.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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 and definitions
For the purposes of this document, the terms and definitions given in IEC 61836 as well as
the following apply.
3.1
PV array simulator
DC power source used to simulate PV array output
3.2
EUT
equipment under test
inverter or anti-islanding device on which these tests are performed
Note 1 to entry: This note applies to the French language only.
3.3
MPPT
maximum power point tracking
PV array control strategy used to maximize the output of the system under the prevailing
conditions
Note 1 to entry: This note applies to the French language only.

– 8 – IEC 62116:2014 © IEC 2014
3.4
non-islanding inverter
inverter that will cease to energize a utility distribution system that is out of the nominal
operation specifications for voltage and/or frequency
[SOURCE: IEC 61727:2004, 3.8.1]
3.5
island
state in which a portion of the electric utility grid, containing load and generation, continues to
operate isolated from the rest of the grid
Note 1 to entry: The generation and loads may be any combination of customer-owned and utility-owned.
3.6
intentional island
island that is intentionally created, usually to restore or maintain power to a section of the
utility grid affected by a fault
Note 1 to entry: The generation and loads may be any combination of customer-owned and utility-owned, but there
is an implicit or explicit agreement between the controlling utility and the operators of customer-owned generation
for this situation.
3.7
quality factor
Q
f
a measure of the strength of resonance of the islanding test load
Note 1 to entry: In a parallel resonant circuit, such as a load on a power system
C
Q = R
f
L
where
Q is quality factor
f
R is effective load resistance
C is reactive load capacitance (including shunt capacitors)
L is reactive load inductance
With C and L tuned to the power system fundamental frequency, Q for the resonant circuit drawing active power, P,
f
reactive powers Q , for inductive load and Q for capacitive load, Q can be determined by
L C f
Q = (1 P) Q ⋅ Q
f L C
where
P is active power, in W
Q is inductive load, in VAr
L L
Q is capacitive load, in VAr
C C
3.8
run-on time
t
R
amount of time that an unintentional island condition exists, calculated as the interval
between the opening of the switch S1 (Figure 1) and the cessation of EUT output current

3.9
stopping signal
signal provided by the inverter indicating it has ceased energizing its utility grid-connected
output terminals
SEE: Annex C.
3.10
unintentional island
islanding condition in which the generation within the island that is supposed to cease
energizing the utility grid instead continues to energize the utility grid
4 Testing circuit
The testing circuit shown in Figure 1 shall be employed. Similar circuits shall be used for
three-phase output.
Parameters to be measured are shown in Table 1 and Figure 1. Parameters to be recorded in
the test report are discussed in Clause 7.

– 10 – IEC 62116:2014 © IEC 2014
Table 1 – Parameters to be measured in real time
Parameter Symbol Units
a, b
EUT DC input
DC voltage V V
DC
DC current I A
DC
DC power P W
DC
c 2
Irradiance G W/m
EUT AC output
b, d, e
AC voltage V V
EUT
b, d, e
I
AC current A
EUT
b
Active power P W
EUT
b
Reactive power Q VAr
EUT
d, e, f, g
Voltage waveform
d, e, f, g
Current waveform
d
EUT (relay) output control signal
Run-on time t s
R
h
Stopping signal SS --
b
Test load
Resistive load current I A
R
Inductive load current I A
L
Capacitive load current I A
C
AC (utility) power source
i
Utility active power P W
AC
i
Utility reactive power Q VAr
AC
i
I
Utility current A
AC
a
If applicable.
b
Record values measured before switch S1 is opened.
c
Recorded when the test is carried out using a PV array. Pyranometer should be fast response silicon-type
not thermopile-type.
d
The response time of voltage and current transducer shall be suitable for the sampling rate used.

e
The waveform, AC voltage and current shall be measured on all phases.
f
The waveform data shall be recorded from the beginning of the islanding test until the EUT ceases output.
The measurement of time shall have an accuracy and resolution of better than 1 ms.
g
When the waveform is recorded, the synchronizing signal of the S1 opening and stopping signal may be
simultaneously recorded.
h
If available from the EUT.
i
Signal shall be filtered as necessary to provide fundamental (50 Hz or 60 Hz) frequency value. Fundamental
values will ignore incidental harmonics, caused by utility voltage distortion, absorbed by the load and EUT
filtering capacitors.
Trigger
Waveform
monitor
V I V I I
DC power DC DC EUT EUT AC AC power
EUT
source source
(inverter)
(PV)
(utility)
P Q S1
P
EUT EUT
DC P Q
AC AC
S2
I I I
R L C
AC loads
IEC  1567/08
Figure 1 – Test circuit for islanding detection
function in a power conditioner (inverter)
5 Testing equipment
5.1 Measuring instruments
Waveform observation shall be measured by a device with memory function, for example, a
storage or digital oscilloscope or a high speed data acquisition system. The waveform
measurement/capture device shall be able to record the waveform from the beginning of the
islanding test until the EUT ceases to energize the island. For multi-phase EUT, all phases
shall be monitored. A waveform monitor designed to detect and calculate the run-on time may
be used.
For multi-phase EUT, the test and measurement equipment shall record each phase current
and each phase-to-neutral or phase-to-phase voltage, as appropriate, to determine
fundamental frequency active and reactive power flow over the duration of the test. A
sampling rate of 10 kHz or higher is recommended. The minimum measurement accuracy
shall be 1 % or less of rated EUT nominal output voltage and 1 % or less of rated EUT output
current. Current, active power, and reactive power measurements through switch S1 used to
determine the circuit balance conditions shall report the fundamental (50 Hz or 60 Hz)
component.
5.2 DC power source
5.2.1 General
A DC power source, such as a PV array simulator, a PV array, or a current and voltage limited
DC power supply with series resistance may be used.
If the EUT can operate in utility-interconnected mode from a storage battery, a DC power
source may be used in lieu of a battery as long as the DC power source shall not be the
limiting device as far as the maximum EUT input current is concerned.
The DC power source shall provide voltage and current necessary to meet the testing
requirements described in Clause 6.

– 12 – IEC 62116:2014 © IEC 2014
5.2.2 PV array simulator
A unit intended to be energized directly from a photovoltaic source shall be energized from a
supply that simulates the current-voltage characteristics and time response of a photovoltaic
array. The tests shall be conducted at the input voltage defined in Table 2 below, and the
current shall be limited to 1,5 times the rated photovoltaic input current, except when
specified otherwise by the test requirements.
A PV array simulator is recommended, however, any type of power source may be used if it
does not influence the test results.
Table 2 – Specification of array simulator (test conditions)
a
Items Conditions
Output power Sufficient to provide maximum EUT output power and other levels specified by test
conditions of Table 5.
b
Response speed The response time of a simulator to a step in output voltage, due to a 5 % load change,
should result in a settling of the output current to within 10 % of its final value in less than
1 ms.
Stability Excluding the variations caused by the EUT MPPT, simulator output power should remain
stable within 2 % of specified power level over the duration of the test: from the point
where load balance is achieved until the island condition is cleared or the allowable run-on
time is exceeded.
c
Fill factor 0,25 to 0,8.
a
For the purposes of this standard, it is assumed that there is no influence of cell technology on islanding
detection.
b
Response speed is indicated to avoid the influence caused by the MPPT control system, the ripple frequency
on the DC side of a EUT, or the active methods of anti-islanding.
c
Fill factor = (V × I )/(V × I ), where V and I are the maximum power point voltage and current,
mp mp oc sc mp mp
respectively, V is the open circuit voltage, and I is the short circuit current. It should be maintained at one
oc sc
value for all test conditions.

5.2.3 Current and voltage limited DC power supply with series resistance
A DC power source used as the EUT input source shall be capable of EUT maximum input
power (so as to achieve EUT maximum output power) at minimum and maximum EUT input
operating voltage.
The power source should provide adjustable current and voltage limit, set to provide the
desired short circuit current and open circuit voltage when combined with the series and shunt
resistance described below.
A series resistance (and, optionally, a shunt resistance) should be selected to provide a fill
factor within the range shown in Table 2.
5.2.4 PV array
A PV array used as the EUT input source shall be capable of EUT maximum input power at
minimum and maximum EUT input operating voltage (see Table 3). Testing is limited to times
when the irradiance varies by no more than 2 % over the duration of the test as measured by
a silicon-type pyranometer or reference device. It may be necessary to adjust the array
configuration to achieve the input voltage and power levels prescribed in 6.1.

Table 3 – PV array test conditions
Items Conditions
Output power Sufficient to provide maximum EUT output power and other levels specified by test
conditions of Table 5.
Climate condition Irradiance, ambient temperature, etc.
To achieve a balanced load condition, the output of the PV array shall be stable. Thus, it is important to perform
the test only during times of stable irradiance (e.g., clear sky, near solar noon).

5.3 AC power source
The utility grid or other AC power source may be used as long as it meets the conditions
specified in Table 4.
Table 4 – AC power source requirements
Items Conditions
Voltage Nominal ± 2,0 %
Voltage THD < 2,5 %
Frequency
Nominal ± 0,1 Hz
a
Phase angle distance 120° ± 1,5°

a
Three-phase case only.
5.4 AC loads
On the AC side of the EUT, variable resistance, capacitance, and inductance shall be
connected in parallel as loads between the EUT and the AC power source. Other sources of
load, such as electronic loads, may be used if it can be shown that the source does not cause
results that are different than would be obtained with passive resistors, inductors, and
capacitors.
All AC loads shall be rated for and adjustable to all test conditions. The equations for Q are

f
based upon an ideal parallel RLC circuit. For this reason, non-inductive resistors, low loss
(high Q ) inductors, and capacitors with low effective series resistance and effective series
f
inductance shall be utilized in the test circuit. Iron core inductors, if used, shall not exceed a
current THD of 2 % when operated at nominal voltage. Load components should be
conservatively rated for the voltage and power levels expected. Resistor power ratings should
be chosen so as to minimize thermally-induced drift in resistance values during the course of
the test.
Active and reactive power should be calculated (using the measurements provided in Table 1)
in each of the R, L and C legs of the load so that these parasitic parameters (and parasitics
introduced by variacs or autotransformers) are properly accounted for when calculating Q .
f
6 Test for single or multi-phase inverter
6.1 Test procedure
The following test is designed for an EUT consisting of a single or multi-phase inverter . The
test uses an RLC load, resonant at the EUT nominal frequency (50 Hz or 60 Hz) and matched
to the EUT output power. For a multi-phase EUT, the load shall be balanced across all phases
—————————
1 Annex B describes the test for an independent islanding detection device (relay).

– 14 – IEC 62116:2014 © IEC 2014
and the switch S1 as in Figure 1 shall open all phases . This test shall be performed with the
EUT conditions as in Table 5, where power and voltage values are given as a percent of EUT
full output rating.
EUT settings for voltage and frequency trip parameters (magnitude and timing) can affect the
measured run-on time. Passing this test verifies that the unit will provide adequate islanding
protection for the settings tested as well as for tighter settings (e.g., an EUT that passes the
test with frequency trip settings of ± 1,5 Hz of nominal should also trip within the maximum
measured run-on time for settings of, say, ± 0,5 Hz.) Conversely, when adjusted to settings
outside of those tested, the EUT may experience extended run-on times. Frequency settings
of ±1,5 Hz around nominal frequency and voltage settings of ± 15 % around nominal voltage,
for the purposes of this test procedure, should be wide enough to address the majority of
utility requirements. Note that as trip settings are widened, more aggressive active anti-
islanding schemes may be required that could negatively impact power quality.
Table 5 – Test conditions
c d
Condition EUT output power, P EUT input voltage EUT trip settings
EUT
a
A Maximum  Voltage and frequency trip
> 75 % of rated input voltage
range settings according to National
standards and/or local code
B 50 % to 66 % of maximum 50 % of rated input voltage Voltage and frequency trip
range, ±10 % settings according to National
standards and/or local code
b
C 25 % to 33 % of maximum < 20 % of rated input voltage Voltage and frequency trip
range settings according to National
standards and/or local code
a
Maximum EUT output power condition should be achieved using the maximum allowable input power. Actual output
power may exceed nominal rated output.
b
Or minimum allowable EUT output level if greater than 33 %.
c
Based on EUT rated input operating range. For example, if range is between X volts and Y volts, 75 % of range
= X + 0,75 × (Y – X). Y shall not exceed 0,8 × EUT maximum system voltage (i.e., maximum allowable array open
circuit voltage). In any case, the EUT should not be operated outside of its allowable input voltage range.
d
The manufacturer shall specify the applicable standard, code or utility based trip settings with which the unit shall
be tested. The manufacturer may also choose more stringent trip settings to demonstrate compatibility with a
greater number of utility requirements. The recommended settings shown below should address the majority of
utility requirements.
Parameter Magnitude Timing
s
Over voltage 115 % of nominal voltage 2
Under voltage 85 % of nominal voltage 2
Over frequency 1,5 Hz above nominal frequency 1
Under frequency 1,5 Hz below nominal frequency 1

If fast over and under voltage and frequency settings are provided, similarly extended values should also be
specified by the manufacturer.

a) Determine the EUT test output power, P , to be used from Table 5. Test conditions A, B,
EUT
and C may be performed in any order convenient to testing.
b) By adjusting the DC input source, operate the EUT at the selected P and measure EUT
EUT
reactive power output, Q , as follows. The utility disconnect switch S1 should be closed.
EUT
With no local load connected (that is, S2 is open so that the RLC load is not connected at
this time), and the EUT connected to the utility (S1 is closed), turn the EUT on and
—————————
2 A loss of one or two phases in a three-phase system is not considered an islanding phenomenon.

operate it at the output determined in step a). Measure the fundamental frequency (50 Hz
or 60 Hz) active and reactive power flow, P and Q . The active power should equal
AC AC
P . The reactive power, Q measured in this step is designated Q in the following
AC AC, EUT
steps.
NOTE 1 EUT output for condition A is achieved by providing sufficient (excess) input power to allow the unit
to produce its maximum output without causing it to shutdown. Condition B is achieved by adjusting the DC
input power source, if the EUT provides this mode of operation. Condition C is achieved using inverter control
to limit the output power, if the EUT provides this mode of operation.
c) Turn off the EUT and open S1.
When the load component levels are adjusted using real-time measurement of resistive,
inductive, and capacitive power levels, it may be necessary to leave S1 closed.
d) Adjust the RLC circuit to have Q = 1,0 ± 0,05 using the following steps:

f
1) Determine the amount of inductive reactance required in the resonant RLC circuit
= Q × P = 1,0 × P .
using the relation Q
L f EUT EUT
2) Connect an inductor as the first element of the RLC circuit. Adjust the inductance to Q .
L
3) Connect a capacitor in parallel with the inductor. Adjust the capacitive reactance so
that Q + Q = – Q .
C L EUT
4) Connect a resistor that results in the power consumed by the RLC circuit equaling
P .
EUT
NOTE 2 Active and reactive power are calculated (using the measurements provided in Table 1) for each of
the R, L and C legs of the load so that these parasitic parameters (and parasitics introduced by variacs or
autotransformers) are properly accounted for when calculating Q .
f
e) Connect the RLC load configured in step d) to the EUT by closing S2. Close S1 and turn
the EUT on, making certain that the power output is as determined in step a). Adjust R, L,
and C as necessary to ensure that the fundamental (50 Hz or 60 Hz) component of current
I through S1 is 0,0 A with a tolerance of ±1 % of the rated current of the EUT on a
AC
steady state basis in each phase.
The purpose of the procedure up to this point is to zero out the fundamental frequency
components (50 Hz or 60 Hz) of active and reactive power, or to zero out the fundamental
frequency component of current flow, at the utility disconnect switch. System resonance
will typically generate harmonic currents in the test circuit. These harmonic currents will
typically make it impossible to zero out an r.m.s. measurement of power or current flow at
the disconnect switch. Because of test equipment measurement error and some impact
from harmonic currents, it may be necessary to make small adjustments in the test circuit
to achieve worst case islanding behavior. Step h) is performed to make these small
adjustments.
f) Open the utility-disconnect switch S1 to initiate the test. Run-on time, t , shall be recorded
R
as the time between the opening of switch S1 and the point at which the EUT output
current drops and remains below 1 % of its rated output levels. Annex C gives some
information related to the use of a gate blocking signal.
g) For test condition A in Table 5 (100 %), adjust the active load and only one of the reactive
load components (either capacitance, C, or inductance, L, may be chosen) to each of the
load imbalance conditions shown in the shaded portion of Table 6. The values in Table 6
represent changes from the nominal values determined in steps d) and e) as a percentage
of those nominal values. The values in Table 6 show the active and reactive power flow at
S1 in Figure 1, with positive value denoting power flow from the EUT to the AC power
source. After each adjustment, an island test is run and run-on time is recorded. If any of
—————————
The appropriate value for Q was investigated using 723 measurement points in Japan. A value of Q was
f f
calculated as the ratio of the contract demand (kW) at the measurement point to the installed shunt capacitor
(kVAr) needed to make the power factor 1,0 at that point. Based on the variety of load conditions encountered,
Q = 1,0 appears to be suitable test condition.
f
Certain anti-islanding algorithms will sufficiently perturb the fundamental frequency current through S1 such
that the 1 % limit cannot be achieved on a continuous basis. Averaging of the r.m.s. current over a number of
cycles in a manner that captures the quiescent magnitude of this current shall be utilized for the determination
of matched load during this quiescent period.

– 16 – IEC 62116:2014 © IEC 2014
the recorded run-on times are longer than the one recorded for the rated balance condition,
i.e. test f), then the non-shaded parameter combinations also require testing. If no run-on
time exceeds the one of balance condition, then this part of the test sequence is deemed
to be completed.
h) For test conditions B and C, adjust only one of reactive load components (either
capacitance, C, or inductance, L, may be chosen) by approximately 1,0 % per test, within
a total
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