IEC TR 61000-3-18:2024

IEC TR 61000-3-18 ®
Edition 1.0 2024-02
TECHNICAL
REPORT
colour
inside
Electromagnetic compatibility (EMC) –
Part 3-18: Limits – Assessment of network characteristics for the application of
harmonic emission limits – Equipment connected to LV distribution systems not
covered by IEC 61000-3-2 and IEC 61000-3-12

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews, graphical symbols and the glossary.
committee, …). It also gives information on projects, replaced With a subscription you will always have access to up to date
and withdrawn publications. content tailored to your needs.

IEC Just Published - webstore.iec.ch/justpublished
Electropedia - www.electropedia.org
Stay up to date on all new IEC publications. Just Published
The world's leading online dictionary on electrotechnology,
details all new publications released. Available online and once
containing more than 22 500 terminological entries in English
a month by email.
and French, with equivalent terms in 25 additional languages.

Also known as the International Electrotechnical Vocabulary
IEC Customer Service Centre - webstore.iec.ch/csc
(IEV) online.
If you wish to give us your feedback on this publication or need

further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TR 61000-3-18 ®
Edition 1.0 2024-02
TECHNICAL
REPORT
colour
inside
Electromagnetic compatibility (EMC) –

Part 3-18: Limits – Assessment of network characteristics for the application of

harmonic emission limits – Equipment connected to LV distribution systems

not covered by IEC 61000-3-2 and IEC 61000-3-12

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10  ISBN 978-2-8322-8219-9

– 2 – IEC TR 61000-3-18:2024 © IEC 2024
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 10
4 General . 10
5 State of existing IEC standards . 12
5.1 Overview of existing standards . 12
5.2 Voltage gaps . 12
5.3 Frequency gaps . 13
5.4 System impedance considerations . 13
6 General approach . 14
7 Detailed implementation of the methodology . 15
7.1 Overview. 15
7.2 European reference network model (RNM) . 15
7.2.1 History . 15
7.2.2 Adjusted RNM for assessing harmonic sensitivity . 16
7.3 Harmonic current model . 18
7.4 Methodology for adapting IEC equipment harmonic emission limits . 20
7.4.1 General . 20
7.4.2 Conversion factor (C ) . 21
fh
7.5 Sensitivity ratio S . 22
R
8 Simulation considerations . 22
8.1 Overview. 22
8.2 Simulation model adjustment . 23
8.3 Studies with only the maximum harmonic distortion of each feeder . 23
8.4 Sampling the feeders of the entire power system . 24
9 Statistical analysis . 24
10 Conclusions . 25
Annex A (informative) Other methods studied for comparing feeder harmonic
sensitivity. 27
A.1 General . 27
A.2 Voltage droop . 27
A.2.1 Explanation . 27
A.2.2 Voltage droop simulation . 27
A.2.3 Concept of the voltage droop approach . 28
A.2.4 Validation of the voltage droop method . 29
A.2.5 Clustering . 30
A.2.6 Feeder parameters . 33
Annex B (informative) Power distribution systems in Canada . 36
B.1 Overview. 36
B.2 Conversion factor . 37
Annex C (informative) Power distribution systems in Japan . 40

C.1 Background for harmonics limits . 40
C.2 Outlook on a typical distribution system in Japan . 40
C.3 Power supply to customers in Japan . 42
C.4 Distribution system impedance in Japan . 42
th
C.5 Case study of 95 percentile and conversion factor in Japan . 43
th
C.6 Comparing the 95 percentile distortion level of Japan vs. EU RNM . 43
Annex D (informative) Example of a Python script used with CYMDIST software . 46
Bibliography . 57

Figure 1 – Reference network medium-voltage power system . 17
Figure 2 – LV network of 153 customers supplied by a 400 kVA transformer . 17
rd th
Figure A.1 – Scatter plot of voltage harmonic levels (3 and 5 ) as function of the
voltage droop . 28
th
Figure A.2 – Comparison of the 95 percentile harmonic levels obtained from
simulation and calculated from the voltage droop . 30
Figure A.3 – q = 1, Manhattan distance . 31
Figure A.4 – q = 2, Euclidian distance . 31
Figure A.5 – Two-parameter k-means clustering example . 32
Figure A.6 – Illustration of SSE . 33
Figure A.7 – Harmonic distortion levels at cluster centroids . 35
Figure B.1 – Low-voltage system in Canada . 36
Figure B.2 – Multi-unit building of 32 customers . 37
Figure B.3 – Buildings with > 1 000 residential customers . 37
Figure C.1 – Overview of the power system in Japan [11] . 41
Figure C.2 – Standard neutral grounding systems for HV and MV distribution system in
Japan . 41
Figure C.3 – Distribution transformer for HV/MV in Japan . 41
Figure C.4 – Popular LV distribution systems in Japan . 42

Table 1 – Modelled RNM voltage distortion compared with compatibility levels . 18
th
Table 2 – 5 harmonic current (h5) per household proposed by [4] . 19
th
Table 3 – 7 harmonic current (h7) per household proposed by [4] . 19
Table 4 – Harmonic load injection at each customer POI in the modelled network . 20
Table 5 – Creating the cumulative data function . 25
Table A.1 – Coefficients of linear regression obtained from the harmonic and droop data . 29
Table B.1 – LV feeder impedance in Canada . 36
Table B.2 – Data for assessing the Canada 240 V limits . 38
Table B.3 – Limits for Class A Equipment . 39
Table C.1 – Impedance survey results for MV distribution lines (Ω) . 42
Table C.2 – Results of long-range survey of MV distribution lines (km) . 43
Table C.3 – Impedance survey results for LV distribution lines (mΩ) . 43
Table C.4 – Data and calculated limits at 100 V in Japan . 44

– 4 – IEC TR 61000-3-18:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 3-18: Limits – Assessment of network characteristics
for the application of harmonic emission limits – Equipment
connected to LV distribution systems not covered
by IEC 61000-3-2 and IEC 61000-3-12

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC
...