Design of earth electrode stations for high-voltage direct current (HVDC) links - General guidelines

IEC TS 62344:2022 is available as IEC TS 62344:2022 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC TS 62344:2022 applies to the design of earth electrode stations for high-voltage direct current (HVDC) links. It is intended to provide necessary guidelines, limits, and precautions to be followed during the design of earth electrodes to ensure safety of personnel and earth electrodes, and reduce any significant impacts on DC power transmission systems and the surrounding environment. This edition includes the following significant technical changes with respect to the previous edition:
- Changed the requirement of earthing resistance limit for short-time unipolar earth system in 5.1.3.
- Corrected the coefficient before ρs from 0,015 9 to 0,008 in touch voltage limit calculation formula (3) in 5.1.5.
- Deleted the analytical calculation formulas of earthing resistance for sea and shore electrodes in 6.1.3.
- Changed the current density limit from 100 A/m2 to 40 A/m2 ~ 50 A/m2 for the sea electrodes that are not accessible to human beings or to marine fauna in 6.1.7.
- Extended some detailed technical requirements for the measurement of ground/water soil parameters in 6.2.5.
- Reformulated the types and characteristics of electrode element material for sea and shore electrodes in 6.3.2.
- Added an informative Annex B: Earth electrode design process.
- Added an informative Annex C: Test results of human body resistance.
- Deleted the formula for calculating the average soil resistivity using harmonic mean when processing the measurement data in D.2.6 of Annex D.
- Extended some detailed technical requirements of electrode online monitoring system in Annex H.
- CIGRE 675:2017 is added to the bibliography.
- Terminology and way of expressions are modified using more commonly used terms in the HVDC electrode design industries and English-speaking countries, so as to make the readers understand the content more easily.

General Information

Status
Published
Publication Date
15-May-2022
Current Stage
PPUB - Publication issued
Completion Date
16-May-2022
Ref Project

Buy Standard

Technical specification
IEC TS 62344:2022 - Design of earth electrode stations for high-voltage direct current (HVDC) links - General guidelines
English language
94 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC TS 62344
Edition 2.0 2022-05
TECHNICAL
SPECIFICATION
colour
inside

Design of earth electrode stations for high-voltage direct current (HVDC) links –

General guidelines
IEC TS 62344:2022-05(en)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2022 IEC, Geneva, Switzerland

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. With a subscription you will always

committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.

and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 19 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
---------------------- Page: 2 ----------------------
IEC TS 62344
Edition 2.0 2022-05
TECHNICAL
SPECIFICATION
colour
inside

Design of earth electrode stations for high-voltage direct current (HVDC) links –

General guidelines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.99 ISBN 978-2-8322-1035-2

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 62344:2022 © IEC 2022
CONTENTS

FOREWORD ........................................................................................................................... 9

INTRODUCTION ................................................................................................................... 11

1 Scope ............................................................................................................................ 12

2 Normative references .................................................................................................... 12

3 Terms and definitions .................................................................................................... 12

4 System conditions ......................................................................................................... 16

4.1 General principles ................................................................................................. 16

4.2 System parameters related to earth electrode design ............................................ 16

4.2.1 Amplitude and duration of the current ............................................................ 16

4.2.2 Polarity .......................................................................................................... 16

4.2.3 Designed lifespan .......................................................................................... 16

4.2.4 Common earth electrodes .............................................................................. 17

5 Design of land electrode stations ................................................................................... 17

5.1 Main technical parameters .................................................................................... 17

5.1.1 General principles ......................................................................................... 17

5.1.2 Temperature rise ........................................................................................... 17

5.1.3 Earthing resistance ........................................................................................ 17

5.1.4 Step voltage .................................................................................................. 18

5.1.5 Touch voltage ................................................................................................ 19

5.1.6 Current density .............................................................................................. 19

5.1.7 Field intensity in fish ponds ........................................................................... 19

5.2 Electrode site selection and parameter measurement ........................................... 19

5.2.1 General principles ......................................................................................... 19

5.2.2 Data collection survey ................................................................................... 20

5.2.3 Distance from converter station (substation) .................................................. 20

5.2.4 Environment conditions, terrain and landform ................................................ 20

5.2.5 Geophysical and geological surveys .............................................................. 20

5.2.6 Topographical map ........................................................................................ 20

5.2.7 Values selected during design ....................................................................... 20

5.3 Earth electrode and associated components ......................................................... 21

5.3.1 General principles for material selection ........................................................ 21

5.3.2 Selection of electrode elements and characteristics ....................................... 21

5.3.3 Chemical and physical properties of petroleum coke ...................................... 22

5.3.4 Current-guiding system .................................................................................. 22

5.3.5 Bus ................................................................................................................ 22

5.3.6 Electrode line and its monitoring device ......................................................... 23

5.4 Electrode arrangement .......................................................................................... 23

5.4.1 General principles ......................................................................................... 23

5.4.2 Filling coke .................................................................................................... 23

5.4.3 Selection of earth electrode shape ................................................................. 23

5.4.4 Earth electrode corridor (right of way) ............................................................ 24

5.4.5 Distance between sub-electrodes in the arrangement .................................... 24

5.4.6 Burial depth of the earth electrodes ............................................................... 24

5.4.7 Segmentation of earth electrodes .................................................................. 25

5.5 Minimum size of earth electrode............................................................................ 25

5.5.1 General principles ......................................................................................... 25

---------------------- Page: 4 ----------------------
IEC TS 62344:2022 © IEC 2022 – 3 –

5.5.2 Total earth electrode length ........................................................................... 25

5.5.3 Area of the surface of the coke-soil interface ................................................. 25

5.5.4 Diameter of electrode elements ..................................................................... 26

5.6 Current guiding system ......................................................................................... 26

5.6.1 General principles ......................................................................................... 26

5.6.2 Placement of the current-guiding wire ............................................................ 26

5.6.3 Connection of current-guiding wire ................................................................ 27

5.6.4 Selection of current-guiding wire cross-section .............................................. 27

5.6.5 Insulation of the current-guiding wire ............................................................. 27

5.6.6 Disconnecting switch ..................................................................................... 27

5.6.7 Connection of the feeding cable ..................................................................... 28

5.6.8 Connection of jumper cables .......................................................................... 28

5.6.9 Selection of cable structure ........................................................................... 28

5.6.10 Selection of cable cross-section .................................................................... 28

5.6.11 Selection of cable insulation .......................................................................... 29

5.6.12 Cable welding position ................................................................................... 29

5.6.13 Welding ......................................................................................................... 29

5.6.14 Mechanical protection for cable ..................................................................... 29

5.7 Auxiliary facilities .................................................................................................. 29

5.7.1 Online monitoring .......................................................................................... 29

5.7.2 Moisture replenishment ................................................................................. 29

5.7.3 Exhaust equipment ........................................................................................ 30

5.7.4 Fence ............................................................................................................ 30

5.7.5 Marker ........................................................................................................... 30

6 Design of sea electrode station and shore electrode station .......................................... 30

6.1 Main technical parameters .................................................................................... 30

6.1.1 General ......................................................................................................... 30

6.1.2 Temperature rise ........................................................................................... 30

6.1.3 Earthing resistance ........................................................................................ 30

6.1.4 Step voltage .................................................................................................. 30

6.1.5 Touch voltage ................................................................................................ 30

6.1.6 Voltage gradient in water ............................................................................... 30

6.1.7 Current density .............................................................................................. 31

6.2 Electrode site selection and parameter measurement ........................................... 31

6.2.1 General principles ......................................................................................... 31

6.2.2 Data collection survey ................................................................................... 31

6.2.3 Distance from converter station (substation) .................................................. 31

6.2.4 Environment conditions ................................................................................. 31

6.2.5 Measurement of ground/water parameters ..................................................... 32

6.3 Earth electrode and associated components ......................................................... 32

6.3.1 General principles for material selection ........................................................ 32

6.3.2 Common electrode elements and characteristics ........................................... 32

6.3.3 Chemical properties of petroleum coke .......................................................... 33

6.3.4 Current-guiding system .................................................................................. 33

6.3.5 Bus ................................................................................................................ 33

6.3.6 Electrode line monitoring device .................................................................... 33

6.4 Electrode arrangement .......................................................................................... 33

6.4.1 General principles ......................................................................................... 33

6.4.2 Filling coke .................................................................................................... 33

---------------------- Page: 5 ----------------------
– 4 – IEC TS 62344:2022 © IEC 2022

6.4.3 Selection of earth electrode shape ................................................................. 33

6.4.4 Segmentation of earth electrodes .................................................................. 34

6.5 Current-guiding system ......................................................................................... 34

6.5.1 Placement of the current-guiding wire ............................................................ 34

6.5.2 Connection of current-guiding system ............................................................ 34

6.5.3 Selection of cable cross-section .................................................................... 35

6.5.4 Insulation of the current-guiding system ......................................................... 35

6.5.5 Selection of cable structure ........................................................................... 35

6.5.6 Mechanical protection for cable ..................................................................... 35

6.6 Auxiliary facilities .................................................................................................. 35

7 Impact on surrounding facilities and mitigation measures .............................................. 35

7.1 Impact on insulated metallic structures and mitigation measures........................... 35

7.1.1 General principles ......................................................................................... 35

7.1.2 Relevant limits ............................................................................................... 36

7.1.3 Mitigation measures....................................................................................... 36

7.2 Impact on bare metallic structures ........................................................................ 36

7.2.1 General principles ......................................................................................... 36

7.2.2 Relevant limits ............................................................................................... 36

7.2.3 Mitigation measures....................................................................................... 36

7.3 Impact on the power system (power transformer, grounding network, and

surrounding towers) .............................................................................................. 36

7.3.1 General principles ......................................................................................... 36

7.3.2 Relevant limits ............................................................................................... 37

7.3.3 Mitigation measures....................................................................................... 37

7.4 Impact on electrified railway .................................................................................. 37

7.5 Other facilities (such as greenhouses and water pipes) ......................................... 37

Annex A (informative) Basic concepts of earth electrodes .................................................... 38

A.1 Basic concepts ...................................................................................................... 38

A.2 Operation mode .................................................................................................... 38

A.2.1 General ......................................................................................................... 38

A.2.2 Monopolar system ......................................................................................... 38

A.2.3 Bipolar system ............................................................................................... 39

A.2.4 Symmetric unbalanced system....................................................................... 41

A.2.5 Back-to-back converter station ...................................................................... 41

A.3 Dangerous impact and accumulated impact .......................................................... 41

A.3.1 General ......................................................................................................... 41

A.3.2 Safety risks of DC earth electrode ................................................................. 41

A.3.3 Accumulated effect of DC earth electrodes .................................................... 46

A.4 Impact on an AC grid ............................................................................................ 47

A.4.1 General ......................................................................................................... 47

A.4.2 DC current path to AC system ....................................................................... 48

A.4.3 DC magnetic bias of AC transformer .............................................................. 48

Annex B (informative) Earth electrode design process ......................................................... 50

B.1 Site selection process ........................................................................................... 50

B.2 Earth electrode design process ............................................................................. 51

Annex C (informative) Test results of human body resistance .............................................. 53

C.1 Basic information of test subjects .......................................................................... 53

C.2 Test method .......................................................................................................... 54

C.3 Test results ........................................................................................................... 54

---------------------- Page: 6 ----------------------
IEC TS 62344:2022 © IEC 2022 – 5 –

Annex D (informative) Soil parameter measurement method ................................................ 57

D.1 General requirements ........................................................................................... 57

D.2 Measurement of resistivity of shallow ground ........................................................ 58

D.2.1 Measurement method of resistivity ................................................................. 58

D.2.2 Measurement requirements ........................................................................... 60

D.2.3 Measurement range ....................................................................................... 61

D.2.4 Data accuracy ............................................................................................... 61

D.2.5 Seasonal coefficient ...................................................................................... 61

D.2.6 Processing of measurement data ................................................................... 61

D.3 Measurement of resistivity of deep soil (MT method) ............................................. 61

D.4 Measurement of soil volume thermal capacity ....................................................... 62

D.5 Measurement of soil thermal conductivity .............................................................. 62

D.6 Measurement of maximum natural temperature of soil .......................................... 63

D.7 Measurement of soil moisture and groundwater table ............................................ 63

D.8 Measurement of soil chemical characteristics ....................................................... 63

D.9 Geological exploration .......................................................................................... 63

D.10 Topographical map ............................................................................................... 63

Annex E (informative) Electrode line design ......................................................................... 64

E.1 Overview............................................................................................................... 64

E.2 Main design principles .......................................................................................... 64

E.3 Selection and layout of conductor and earth wire .................................................. 65

E.3.1 Selection of conductor ................................................................................... 65

E.3.2 Selection of earth wire ................................................................................... 65

E.3.3 Layout of conductor and earth wire ................................................................ 65

E.4 Insulation coordination and earthing for lightning protection .................................. 65

E.4.1 Type and number of insulators ....................................................................... 65

E.4.2 Arcing horn gap ............................................................................................. 65

E.4.3 Earthing for lightning protection ..................................................................... 66

E.5 Other considerations ............................................................................................. 66

Annex F (informative) Assessment of measurement method ................................................ 67

F.1 General guidance .................................................................................................. 67

F.2 Experiment (testing) items .................................................................................... 67

F.2.1 Visual inspection of the earth electrode ......................................................... 67

F.2.2 Current guiding system current distribution measurement .............................. 67

F.2.3 Measurement of earthing resistance .............................................................. 68

F.2.4 Measurement of step voltage on the ground and potential gradient in

water near the earth electrode ....................................................................... 68

F.2.5 Measurement of touch voltage ....................................................................... 69

F.2.6 Measurement of soil surface potential profile ................................................. 69

F.2.7 Measurement of earth electrode temperature rise .......................................... 70

Annex G (informative) Earth electrode electrical parameter calculation method.................... 71

G.1 General ................................................................................................................. 71

G.2 Network method calculation model for DC earth electrode .................................... 71

G.3 Moment method calculation model for DC earth electrodes ................................... 71

G.4 Finite element method calculation model for DC earth electrodes ......................... 76

G.5 Calculation of earthing resistance, step voltage, touch voltage, electric field

intensity and current density ................................................................................. 78

G.5.1 General ......................................................................................................... 78

G.5.2 Calculation of earthing resistance .................................................................. 78

---------------------- Page: 7 ----------------------
– 6 – IEC TS 62344:2022 © IEC 2022

G.5.3 Calculation of step voltage ............................................................................. 78

G.5.4 Calculation of touch voltage ........................................................................... 78

G.5.5 Calculation of electric field intensity ............................................................... 78

G.5.6 Calculation of current density ........................................................................ 79

G.6 Application description .......................................................................................... 79

G.6.1 Original parameters ....................................................................................... 79

G.6.2 Example using the moment method ............................................................... 79

Annex H (informative) Thermal time constant ....................................................................... 82

Annex I (informative) Online monitoring system ................................................................... 84

I.1 Schematic diagram of online monitoring system .................................................... 84

I.2 Composition of online monitoring system .............................................................. 84

Annex J (informative) Calculation method for corrosion of nearby metal structures

caused by earth electrodes ............................................................................................ 86

J.1 Consumption of metal structure due to corrosion .................................................. 86

J.2 Estimate of leakage current in metal pipes ............................................................ 86

J.3 Calculation of the leakage current of the metal pipe .............................................. 87

Annex K (informative) Calculation method for DC current flowing through AC

transformer neutral near earth electrodes ............................................................................. 88

Annex L (informative) Chemical processes in sea electrodes ............................................... 91

Annex M (informative) Simple introduction of shore electrodes ............................................ 92

M.1 General ................................................................................................................. 92

M.2 Beach electrodes .................................................................................................. 92

M.3 Pond electrodes .................................................................................................... 92

Bibliography .......................................................................................................................... 94

Figure 1 – Electrode cross-section ........................................................................................ 23

Figure 2 – Vertical arrangement ............................................................................................ 24

Figure 3 – Placement of the current-guiding wire .................................................................. 27

Figure 4 – Feeding cable ...................................................................................................... 28

Figure 5 – Sea electrode ....................................................................................................... 33

Figure 6 – Sea bottom electrode with titanium nets ............................................................... 34

Figure 7 – Titanium net ......................................................................................................... 35

Figure 8 – Impact of earth electrodes on AC systems (transformer, grounding network,

tower) ................................................................................................................................... 37

Figure A.1 – HVDC power transmission system structure ...................................................... 38

Figure A.2 – Schematic diagram of monopolar earth/sea water return system ....................... 39

Figure A.3 – Schematic diagram of monopolar dedicated metallic return system ................... 39

Figure A.4 – Schematic diagram of bipolar earth/sea water system ...
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.