Electromagnetic performance of high voltage direct current (HVDC) overhead transmission lines

IEC TR 62681:2022 is available as IEC TR 62681:2022 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC TR 62681:2022 provides general guidance on the electromagnetic environment issues of HVDC overhead transmission lines. It concerns the major parameters adopted to describe the electromagnetic properties of an HVDC overhead transmission line, including electric fields, ion current, magnetic fields, radio interference, and audible noise generated as a consequence of such effects. If the evaluation method and/or criteria of electromagnetic properties are not yet regulated, engineers in different countries can refer to this document to:
- support/guide the electromagnetic design of HVDC overhead transmission lines,
- limit the influence on the environment within acceptable ranges, and
- optimize engineering costs.

General Information

Status
Published
Publication Date
24-May-2022
Current Stage
PPUB - Publication issued
Completion Date
25-May-2022
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IEC TR 62681
Edition 2.0 2022-05
TECHNICAL
REPORT
colour
inside
Electromagnetic performance of high voltage direct current (HVDC) overhead
transmission lines
IEC TR 62681:2022-05(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 62681
Edition 2.0 2022-05
TECHNICAL
REPORT
colour
inside
Electromagnetic performance of high voltage direct current (HVDC) overhead
transmission lines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.20 ISBN 978-2-8322-3130-2

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 62681:2022 © IEC 2022
CONTENTS

FOREWORD ........................................................................................................................... 6

INTRODUCTION ..................................................................................................................... 8

1 Scope .............................................................................................................................. 9

2 Normative references ...................................................................................................... 9

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

4 Electric field and ion current .......................................................................................... 10

4.1 Description of the physical phenomena ................................................................. 10

4.2 Calculation methods ............................................................................................. 14

4.2.1 General ......................................................................................................... 14

4.2.2 Semi-analytic method .................................................................................... 15

4.2.3 Finite element method ................................................................................... 17

4.2.4 BPA method .................................................................................................. 18

4.2.5 Empirical methods of EPRI ............................................................................ 18

4.2.6 Recent progress ............................................................................................ 19

4.3 Experimental data ................................................................................................. 20

4.3.1 General ......................................................................................................... 20

4.3.2 Instrumentation and measurement methods ................................................... 20

4.3.3 Experimental results for electric field and ion current ..................................... 22

4.3.4 Discussion ..................................................................................................... 22

4.4 Implication for human and nature .......................................................................... 23

4.4.1 General ......................................................................................................... 23

4.4.2 Static electric field ......................................................................................... 23

4.4.3 Research on space charge ............................................................................ 24

4.4.4 Scientific review ............................................................................................ 29

4.5 Design practice of different countries .................................................................... 31

5 Magnetic field ................................................................................................................ 32

5.1 Description of physical phenomena ....................................................................... 32

5.2 Magnetic field of HVDC transmission lines ............................................................ 32

6 Radio interference ......................................................................................................... 33

6.1 Description of radio interference phenomena of HVDC transmission system ......... 33

6.1.1 General ......................................................................................................... 33

6.1.2 Physical aspects of DC corona ...................................................................... 33

6.1.3 Mechanism of formation of a noise field of DC line......................................... 34

6.1.4 Characteristics of radio interference from DC line .......................................... 34

6.1.5 Factors influencing the RI from DC line .......................................................... 35

6.2 Calculation methods ............................................................................................. 37

6.2.1 EPRI empirical formula .................................................................................. 37

6.2.2 IREQ empirical method .................................................................................. 38

6.2.3 CISPR bipolar line RI prediction formula ........................................................ 39

6.3 Experimental data ................................................................................................. 40

6.3.1 Measurement apparatus and methods ........................................................... 40

6.3.2 Experimental results for radio interference ..................................................... 40

6.4 Criteria of different countries ................................................................................. 40

7 Audible noise ................................................................................................................. 41

7.1 Basic principles of audible noise ........................................................................... 41

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IEC TR 62681:2022 © IEC 2022 – 3 –

7.2 Description of physical phenomena ....................................................................... 43

7.2.1 General ......................................................................................................... 43

7.2.2 Lateral profiles ............................................................................................... 44

7.2.3 Statistical distribution .................................................................................... 47

7.2.4 Influencing factors ......................................................................................... 48

7.2.5 Effect of altitude above sea level ................................................................... 50

7.2.6 Concluding remarks ....................................................................................... 50

7.3 Calculation methods ............................................................................................. 50

7.3.1 General ......................................................................................................... 50

7.3.2 Theoretical analysis of audible noise propagation .......................................... 50

7.3.3 Empirical formulas of audible noise ............................................................... 51

7.3.4 Semi-empirical formulas of audible noise ....................................................... 52

7.3.5 Concluding remarks ....................................................................................... 55

7.4 Experimental data ................................................................................................. 55

7.4.1 Measurement techniques and instrumentation ............................................... 55

7.4.2 Experimental results for audible noise ........................................................... 55

7.5 Design practice of different countries .................................................................... 56

7.5.1 General ......................................................................................................... 56

7.5.2 The effect of audible noise on people ............................................................ 56

7.5.3 The audible noise level and induced complaints ............................................ 56

7.5.4 Limit values of audible noise of HVDC transmission lines in different

countries ....................................................................................................... 60

7.5.5 General national noise limits .......................................................................... 60

Annex A (informative) Experimental results for electric field and ion current......................... 62

A.1 Bonneville Power Administration ±500 kV HVDC transmission line ........................ 62

A.2 FURNAS ±600 kV HVDC transmission line ............................................................ 62

A.3 Manitoba Hydro ±450 kV HVDC transmission line ................................................. 63

A.4 Hydro-Québec – New England ±450 kV HVDC transmission line ........................... 65

A.5 IREQ test line study of ±450 kV HVDC line configuration ...................................... 66

A.6 HVTRC test line study of ±400 kV HVDC line configuration ................................... 67

A.7 Test study in China ............................................................................................... 68

Annex B (informative) Experimental results for radio interference ........................................ 71

B.1 Bonneville power administration’s 1 100 kV direct current test project ................... 71

B.1.1 General ......................................................................................................... 71

B.1.2 Lateral profile ................................................................................................ 71

B.1.3 Influence of conductor gradient ...................................................................... 72

B.1.4 Percent cumulative distribution ...................................................................... 73

B.1.5 Influence of wind ........................................................................................... 75

B.1.6 Spectrum ....................................................................................................... 75

B.2 Hydro-Québec institute of research ....................................................................... 77

B.2.1 General ......................................................................................................... 77

B.2.2 Cumulative distribution .................................................................................. 77

B.2.3 Spectrum ....................................................................................................... 78

B.2.4 Lateral profiles ............................................................................................... 78

B.3 DC lines of China .................................................................................................. 79

Annex C (informative) Experimental results for audible noise ............................................... 82

Bibliography .......................................................................................................................... 86

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– 4 – IEC TR 62681:2022 © IEC 2022

Figure 1 – Monopolar and bipolar space charge regions of an HVDC transmission line [1] .... 11

Figure 2 – Lateral profile of magnetic field on the ground of ±800 kV HVDC lines ................. 33

Figure 3 – The corona current I and radio interference magnetic field H ............................... 34

Figure 4 – RI tolerance tests: reception quality as a function of signal-to-noise ratio ............. 41

Figure 5 – Attenuation of different weighting networks used in audible-noise

measurements [16] ............................................................................................................... 42

Figure 6 – Comparison of typical audible noise frequency spectra [131] ................................ 44

Figure 7 – Lateral profiles of the AN ..................................................................................... 45

Figure 8 – Lateral profiles of the AN from a bipolar HVDC-line equipped with

8 × 4,6 cm (8 × 1,8 in) conductor bundles energized with ±1 050 kV [133] ............................ 45

Figure 9 – Lateral profiles of fair-weather A-weighted sound level [131] ................................ 46

Figure 10 – All weather distribution of AN and RI at +15 m lateral distance of the

positive pole from the upgraded Pacific NW/SW HVDC Intertie [34] ...................................... 47

Figure 11 – Statistical distributions of fair weather A-weighted sound level measured at

27 m lateral distance from the line center during spring 1980 ................................................ 48

Figure 12 – Audible noise complaint guidelines [14] in USA .................................................. 57

Figure 13 – Measured lateral profile of audible noise on a 330 kV AC transmission line

[151] ..................................................................................................................................... 57

Figure 14 – Subjective evaluation of DC transmission line audible noise; EPRI test

center study 1974 [14] .......................................................................................................... 58

Figure 15 – Subjective evaluation of DC transmission line audible noise; OSU study

1975 [14] .............................................................................................................................. 58

Figure 16 – Results of the operators’ subjective evaluation of AN from HVDC lines .............. 59

Figure 17 – Results of subjective evaluation of AN from DC lines ......................................... 59

Figure A.1 – Electric field and ion current distributions for Manitoba Hydro ±450 kV

Line [39] ............................................................................................................................... 64

Figure A.2 – Cumulative distribution of electric field for Manitoba Hydro ±450 kV Line [39] ... 64

Figure A.3 – Cumulative distribution of ion current density for Manitoba Hydro ±450 kV

line [39] ................................................................................................................................ 65

Figure A.4 – Test result for total electric field at different humidity [119] ............................... 69

Figure A.5 – Comparison between the calculation result and test result for the total

electric field (minimum conductor height is 18 m) [119] ......................................................... 70

Figure B.1 – Connection for 3-section DC test line [123] ....................................................... 71

Figure B.2 – Typical RI lateral profile at ±600 kV, 4 × 30,5 mm conductor, 11,2 m pole

spacing, 15,2 m average height [14] ..................................................................................... 72

Figure B.3 – Simultaneous RI lateral, midspan, in clear weather and light wind for three

configurations, bipolar ±400 kV [123] .................................................................................... 72

Figure B.4 – RI at 0,834 MHz as a function of bipolar line voltage 4 × 30,5 mm

conductor, 11,2 m pole spacing, 15,2 m average height ........................................................ 73

Figure B.5 – Percent cumulative distribution for fair weather, 2 × 46 mm, 18,3 m pole

spacing, ±600 kV .................................................................................................................. 73

Figure B.6 – Percent cumulative distribution for rainy weather, 2 × 46 mm, 18,3 m pole

spacing, ±600 kV .................................................................................................................. 74

Figure B.7 – Percent cumulative distribution for fair weather, 4 × 30,5 mm, 13,2 m pole

spacing, ±600 kV .................................................................................................................. 74

Figure B.8 – Percent cumulative distribution for rainy weather, 4 × 30,5 mm, 13,2 m

pole spacing, ±600 kV ........................................................................................................... 75

Figure B.9 – Radio interference frequency spectrum ............................................................. 76

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IEC TR 62681:2022 © IEC 2022 – 5 –

Figure B.10 – RI vs. frequency at ±400 kV [123] ................................................................... 76

Figure B.11 – Cumulative distribution of RI measured at 15 m from the positive pole [124] ... 77

Figure B.12 – Conducted RI frequency spectrum measured with the line terminated at

one end [124] ........................................................................................................................ 78

Figure B.13 – Lateral profile of RI [124] ................................................................................ 79

Figure B.14 – Comparison between calculation result and test result for RI lateral

profile [119] .......................................................................................................................... 80

Figure B.15 – The curve with altitude of the RI on positive reduced-scale test lines .............. 81

Figure C.1 – Examples of statistical distributions of fair weather audible noise. dB(A)

measured at 27 m from line center of a bipolar HVDC test line [16] ....................................... 83

Figure C.2 – AN under the positive polar test lines varying with altitude ................................ 85

Table 1 – Electric field and ion current limits of ±800 kV DC lines in China ........................... 31

Table 2 – Electric field limits of DC lines in United States of America [121] ........................... 31

Table 3 – Electric field and ion current limits of DC lines in Canada ...................................... 31

Table 4 – Electric field limits of DC lines in Brazil ................................................................. 31

Table 5 – Parameters of the IREQ excitation function (Monopolar) [122] ............................... 39

Table 6 – Parameters of the IREQ excitation function (Bipolar) [122] .................................... 39

Table 7 – Parameters defining regression equation for generated acoustic power

density [8] ............................................................................................................................. 54

Table 8 – Typical sound attenuation (in decibels) provided by buildings [157] ....................... 61

Table A.1 – BPA ±500 kV line: statistical summary of all-weather ground-level electric

field intensity and ion current density [34] ............................................................................. 62

Table A.2 – FURNAS ±600 kV line: statistical summary of ground-level electric field

intensity and ion current density [38] ..................................................................................... 63

Table A.3 – Hydro-Québec–New England ±450 kV HVDC transmission line. Bath, NH;

1990-1992 (fair weather), 1992 (rain), All-season measurements of static electric E-field

in kV/m [41] .......................................................................................................................... 66

Table A.4 – Hydro-Québec – New England ±450 kV HVDC Transmission Line. Bath,
NH; 1990-1992, All-season fair-weather measurements of ion concentrations in

kions/cm [41] ...................................................................................................................... 66

Table A.5 – IREQ ±450 kV test line: statistical summary of ground-level electric field

intensity and ion current density [43] ..................................................................................... 67

Table A.6 – HVTRC ±400 kV test line: statistical summary of peak electric field and ion

currents [44] ......................................................................................................................... 68

Table A.7 – Statistical results for the test data of total electric field at ground (50 %

value) [119] ........................................................................................................................... 69

Table B.1 – Influence of wind on RI ...................................................................................... 75

Table B.2 – Statistical representation of the long term RI performance of the tested

conductor bundle [124] ......................................................................................................... 78

Table B.3 – RI at 0,5 MHz at lateral 20 m from positive pole (fair weather) ........................... 79

Table B.4 – The parameters of test lines ............................................................................... 80

Table B.5 – Measured results of 0,5 MHz RI for the full-scale test lines at different

altitudes ................................................................................................................................ 81

Table C.1 – Audible Noise Levels of HVDC Lines according to [121] and [152] ..................... 84

Table C.2 – Test results of 50 % AN statistics for full-scale test lines .................................... 85

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– 6 – IEC TR 62681:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC PERFORMANCE OF HIGH VOLTAGE DIRECT
CURRENT (HVDC) OVERHEAD TRANSMISSION LINES
FOREWORD

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IEC TR 62681 has been prepared by IEC technical committee 115: High Voltage Direct Current

(HVDC) transmission for DC voltages above 100 kV. It is a Technical Report.

This second edition cancels and replaces the first edition, published in 2014. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) the limits of total electric field in some countries have been supplemented and improved;

b) the definition of 80 %/80 % criteria of radio interference has been clarified;

c) a table has been added for bipolar excitation which shows the parameters of the IREQ radio

interference excitation function;
d) the clause of CEPRI research results of audible noise has been deleted;
e) the clause of main conclusion of audible noise has been deleted.
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IEC TR 62681:2022 © IEC 2022 – 7 –
The text of this Technical Report is based on the following documents:
Draft Report on voting
115/289/DTR 115/292/RVDTR

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 Report is English.

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