IEC TR 61000-3-18:2024

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

IEC TR 61000-3-18:2024 which is a technical report, reports on the development of a methodology for adapting IEC equipment emission limits from IEC 61000-3-2 and IEC 61000-3-12 for use in regions not covered by these documents. It identifies gaps in the existing equipment emission limit standards concerning their international applicability and identifies public power system characteristics important for the evaluation of harmonic voltage performance. The purpose of adapting the above-mentioned IEC equipment harmonic emission standards in a particular region is to maintain similar electromagnetic compatibility (EMC) of equipment up to 75 A per phase in the public power systems in those regions.
NOTE The boundaries between the various voltage levels differ amongst different countries (see IEC 60050‑601:1985, 601-01-28). This document uses the following terms when referring to 50 Hz and 60 Hz system voltages:
- low voltage (LV) refers to Un ≤ 1 kV;
- medium voltage (MV) refers to 1 kV  - high voltage (HV) refers to 35 kV  EMC requirements can have economic and societal impacts; these have not been considered in the development of this document. The consideration of these factors generally occurs in the technical committees working on development and maintenance of emission limit standards.

General Information

• Status: Published
• Publication Date: 05-Feb-2024
• ICS: 33.100.10 - Emission
• Technical Committee: SC 77A - EMC - Low frequency phenomena
• Drafting Committee: PT 61000-3-18 - TC 77/SC 77A/PT 61000-3-18
• Current Stage: PPUB - Publication issued
• Start Date: 08-Mar-2024
• Completion Date: 06-Feb-2024

Standards Content (Sample)

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

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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,
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may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC
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