Guideline for the system design of HVDC converter stations with line-commutated converters

IEC TR 63127:2019(E) focuses on the system design of converter stations. It is applicable to point-­to-­point and back-to-back HVDC systems based on line-commutated converter (LCC) technology. This document provides guidance and supporting information on the procedure for system design and the technical issues involved in the system design of HVDC transmission projects for both purchaser and potential suppliers. It can be used as the basis for drafting a procurement specification and as a guide during project implementation.

General Information

Status
Published
Publication Date
25-Jun-2019
Current Stage
PPUB - Publication issued
Completion Date
26-Jun-2019
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IEC TR 63127:2019 - Guideline for the system design of HVDC converter stations with line-commutated converters
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IEC TR 63127
Edition 1.0 2019-06
TECHNICAL
REPORT
Guideline for the system design of HVDC converter stations with line-
commutated converters
IEC TR 63127:2019-06(en)
---------------------- Page: 1 ----------------------
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IEC TR 63127
Edition 1.0 2019-06
TECHNICAL
REPORT
Guideline for the system design of HVDC converter stations with line-
commutated converters
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.01; 29.240.10 ISBN 978-2-8322-7068-4

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 63127:2019  IEC:2019
CONTENTS

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

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

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

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

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

4 Symbols ........................................................................................................................ 10

4.1 Letter symbols for variables .................................................................................. 10

4.2 Subscripts ............................................................................................................. 11

5 Overview of HVDC system design ................................................................................. 11

5.1 General ................................................................................................................. 11

5.2 Formulation of system design ............................................................................... 13

5.2.1 HVDC system ratings ..................................................................................... 13

5.2.2 HVDC system configuration ........................................................................... 13

5.2.3 Reactive power compensation and control ..................................................... 13

5.2.4 AC/DC interaction and control........................................................................ 13

5.2.5 Insulation coordination ................................................................................... 14

5.2.6 AC/DC harmonic filtering ............................................................................... 14

5.2.7 Environmental considerations ........................................................................ 14

5.3 System studies and simulations ............................................................................ 14

6 Determination of design conditions and requirements .................................................... 16

6.1 Environmental conditions and requirements .......................................................... 16

6.2 DC transmission line (cable) and earth electrode .................................................. 17

6.2.1 Parameters of DC overhead transmission line ............................................... 17

6.2.2 Parameters of DC cable ................................................................................. 18

6.2.3 Parameters of electrode line and ground electrode ........................................ 18

6.3 AC system conditions............................................................................................ 18

6.3.1 Operating scenarios of AC/DC system ........................................................... 18

6.3.2 AC system modelling ..................................................................................... 18

6.3.3 Relevant AC system protection ...................................................................... 19

6.3.4 Reactive power supply and absorption ........................................................... 19

6.3.5 Short-circuit current or capacity ..................................................................... 20

6.3.6 AC bus voltage .............................................................................................. 20

6.3.7 AC system frequency ..................................................................................... 21

6.3.8 Pre-existing harmonic and negative sequence voltage ................................... 21

6.4 Requirements for HVDC systems arising from AC/DC interaction .......................... 22

6.5 AC system equivalents .......................................................................................... 23

6.5.1 General ......................................................................................................... 23

6.5.2 Equivalent for AC/DC system dynamic or transient simulation ....................... 23

6.5.3 Impedance equivalent for AC filter design ...................................................... 24

6.5.4 System equivalent for low order harmonic resonance study ........................... 25

7 Main circuit design ......................................................................................................... 26

7.1 Ratings ................................................................................................................. 26

7.1.1 Rated power .................................................................................................. 26

7.1.2 Rated voltage ................................................................................................ 27

7.1.3 Rated current ................................................................................................. 28

7.2 Configurations ...................................................................................................... 28

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IEC TR 63127:2019  IEC:2019 – 3 –

7.2.1 Pole and return path ...................................................................................... 28

7.2.2 Converter topology ........................................................................................ 29

7.2.3 DC switchyard configuration .......................................................................... 30

7.2.4 Reactive power equipment ............................................................................. 38

7.3 Determination of main circuit parameters .............................................................. 38

7.3.1 General ......................................................................................................... 38

7.3.2 Control strategy ............................................................................................. 39

7.3.3 Tolerances and errors .................................................................................... 40

7.3.4 Determination of converter transformer impedance ........................................ 40

7.3.5 Relative inductive voltage drop (d ) and relative resistive voltage drop

(d ) .............................................................................................................. 40

7.3.6 Ideal no-load DC voltage ............................................................................... 41

7.3.7 DC voltage and DC current ............................................................................ 41

7.3.8 Rated capacity of converter transformer ........................................................ 42

7.3.9 Converter transformer taps ............................................................................ 43

7.3.10 Inductance of smoothing reactor .................................................................... 44

8 Insulation coordination................................................................................................... 44

9 Filter design .................................................................................................................. 45

9.1 General ................................................................................................................. 45

9.2 AC filter design ..................................................................................................... 45

9.3 DC filter design ..................................................................................................... 45

9.4 Power line carrier (PLC) filters .............................................................................. 46

9.5 Radio frequency interference (RFI) ....................................................................... 46

10 Reactive power compensation and control ..................................................................... 47

10.1 General ................................................................................................................. 47

10.2 Reactive power consumption ................................................................................ 47

10.2.1 Reactive power consumption calculation ........................................................ 47

10.2.2 Maximum reactive power consumption ........................................................... 48

10.2.3 Minimum reactive power consumption ........................................................... 48

10.3 Determination of reactive power equipment capacity ............................................. 48

10.3.1 General ......................................................................................................... 48

10.3.2 Capacity of reactive power supply equipment ................................................ 48

10.3.3 Capacity of reactive power absorption equipment .......................................... 48

10.3.4 Sizing of reactive power sub-bank ................................................................. 49

10.3.5 Sizing of reactive power bank ........................................................................ 49

10.4 Reactive power control ......................................................................................... 49

10.4.1 General ......................................................................................................... 49

10.4.2 Reactive power exchange control/voltage control .......................................... 50

10.4.3 Voltage limitation ........................................................................................... 50

10.5 Temporary overvoltage control .............................................................................. 51

11 Basic parameters of main equipment ............................................................................. 51

11.1 General ................................................................................................................. 51

11.2 Converter valves ................................................................................................... 51

11.2.1 General ......................................................................................................... 51

11.2.2 Valve hall environment .................................................................................. 51

11.2.3 Current rating ................................................................................................ 52

11.2.4 Voltage rating ................................................................................................ 52

11.2.5 Losses of converter valves ............................................................................ 53

11.2.6 Testing requirements ..................................................................................... 53

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– 4 – IEC TR 63127:2019  IEC:2019

11.3 Converter transformers ......................................................................................... 53

11.3.1 General ......................................................................................................... 53

11.3.2 Current rating ................................................................................................ 54

11.3.3 Voltage rating ................................................................................................ 54

11.3.4 Other rating ................................................................................................... 54

11.3.5 Rated loss ..................................................................................................... 54

11.3.6 Test requirements .......................................................................................... 55

11.4 Smoothing reactor................................................................................................. 55

11.4.1 General ......................................................................................................... 55

11.4.2 Current ratings............................................................................................... 55

11.4.3 Voltage rating ................................................................................................ 56

11.4.4 Other ratings ................................................................................................. 56

11.4.5 Losses ........................................................................................................... 56

11.4.6 Test requirements .......................................................................................... 56

11.5 Wall bushings ....................................................................................................... 56

11.5.1 General ......................................................................................................... 56

11.5.2 Current rating ................................................................................................ 56

11.5.3 Voltage rating ................................................................................................ 56

11.5.4 Testing requirement ....................................................................................... 56

11.6 AC and DC filter equipment ................................................................................... 57

11.7 PLC filter equipment ............................................................................................. 57

11.8 Other equipment in DC yard .................................................................................. 57

Annex A (informative) Typical control, measurement and equipment manufacturing

tolerance in HVDC systems .................................................................................................. 58

Annex B (informative) Technical parameters for equipment specification ............................. 59

B.1 Converter valve..................................................................................................... 59

B.2 Converter transformer ........................................................................................... 61

B.3 Smoothing reactor................................................................................................. 62

Bibliography .......................................................................................................................... 63

Figure 1 – System design in an HVDC project ....................................................................... 12

Figure 2 – Example of schematic diagram of AC system frequency variation range ............... 21

Figure 3 – Sector diagram of system harmonic impedance .................................................... 24

Figure 4 – Circle diagram of system harmonic impedance ..................................................... 25

Figure 5 – Structure of equivalent network for low order harmonic resonance study .............. 26

Figure 6 – Converter transformer connection topology .......................................................... 30

Figure 7 – Sketch maps of the DC yard switches of HVDC system ........................................ 33

Figure 8 – Schematic diagram of converter parallel connection ............................................. 33

Figure 9 – Schematic diagram of pole line parallel connection .............................................. 34

Figure 10 – Procedure of NBS disconnecting DC fault .......................................................... 34

Figure 11 – Current transfer path of the MRTS...................................................................... 35

Figure 12 – Current transfer path of ERTS ............................................................................ 35

Figure 13 – Connection and function of the NBES ................................................................. 36

Figure 14 – Commutating process of NBES in case of DMR .................................................. 36

Figure 15 – High speed bypass switch .................................................................................. 37

Figure 16 – Converter paralleling switches ............................................................................ 37

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IEC TR 63127:2019  IEC:2019 – 5 –

Table 1 – Studies and simulations in HVDC system design ................................................... 15

Table 2 – Preferred rated voltages for overhead line HVDC power transmission ................... 27

Table 3 – Preferred rated voltages for submarine HVDC power transmission ........................ 27

Table A.1 – Tolerance for main circuit calculation ................................................................. 58

Table A.2 – Control parameters for main circuit calculation ................................................... 58

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– 6 – IEC TR 63127:2019  IEC:2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDELINE FOR THE SYSTEM DESIGN OF HVDC CONVERTER
STATIONS WITH LINE-COMMUTATED CONVERTERS
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,

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with the International Organization for Standardization (ISO) in accordance with conditions determined by

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6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

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.

The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".
IEC TR 63127, which is a Technical Report, has been prepared by IEC technical

committee 115: High Voltage Direct Current (HVDC) transmission for DC voltages above

100 kV.
The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
115/195/DTR 115/203/RVDTR

Full information on the voting for the approval of this Technical Report can be found in the

report on voting indicated in the above table.
---------------------- Page: 8 ----------------------
IEC TR 63127:2019  IEC:2019 – 7 –

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
---------------------- Page: 9 ----------------------
– 8 – IEC TR 63127:2019  IEC:2019
INTRODUCTION

HVDC is an established technology that has been in commercial use for more than 60 years.

With the changes in demands due to evolving environmental needs, installation of HVDC

systems has increased dramatically in the last 30 years and almost half of HVDC projects

were commissioned after the year 2000. HVDC has become a common tool in the design of

future global transmission systems.

HVDC systems transmit more electrical power over longer distances than a similar alternating

current (AC) transmission system, which means fewer transmission lines are needed, saving

both money and land and simplifying permissions. In addition to significantly lowering

electrical losses over long distances, HVDC transmission is also very stable and easily

controlled, and can stabilize and interconnect AC power networks that are otherwise

incompatible. Typically HVDC systems provide unique or superior capabilities in the following

aspects:
• long distance bulk power transmission;
• asynchronous interconnections;
• long distance cable;
• controllability;
• lower losses;
• environmental concerns;
• limitation of short-circuit currents.

Simply due to these technical merits, the market demand for HVDC transmission technology

is spreading widely over the world. There are many HVDC power transmission systems with a

DC voltage from 50 kV up to 660 kV in different countries. In addition, there are several

±800 kV HVDC power transmission systems which have been built or operated or which are

under construction in China, India and Brazil. In 2016, one ±1 100 kV HVDC power
transmission system project was started in China.

The fast development of the HVDC power transmission and distribution industry has been

accompanied by IEC standardization work. More than 40 IEC documents, from DC equipment

to DC systems, have been published. Among these, the IEC TR 60919 series, IEC 60633,

IEC 60071-5, the IEC TR 62001 series and the IEC 60700 series provide essential information

for the design and operation of HVDC power transmission systems.

However, this document provides only a basic guide and refers to typical numbers and

examples. Other points and values may also be valid in particular cases and should also be

considered accordingly.
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IEC TR 63127:2019  IEC:2019 – 9 –
GUIDELINE FOR THE SYSTEM DESIGN OF HVDC CONVERTER
STATIONS WITH LINE-COMMUTATED CONVERTERS
1 Scope

System design is the basis of construction and operation of HVDC systems. It defines the

overall philosophy for the HVDC transmission system and enables the ratings and
specifications for the equipment integrated in the project.

This document focuses on the system design of converter stations. It is applicable to point-to-

point and back-to-back HVDC systems based on line-commutated converter (LCC) technology.

This document provides guidance and supporting information on the procedure for system

design and the technical issues involved in the system design of HVDC transmission projects

for both purchaser and potential suppliers. It can be used as the basis for drafting a

procurement specification and as a guide during project implementation.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.
IEC 60633, High-voltage direct current (HVDC) transmission – Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60633 apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
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– 10 – IEC TR 63127:2019  IEC:2019
4 Symbols
4.1 Letter symbols for variables

U DC voltage between the pole and the neutral bus at the line side of the smoothing

reactor
U DC voltage of pole line to ground at the measuring point
I DC current
U measured DC voltage
dmeas

P power setting at the line side of the smoothing reactor in the rectifier station

ref
X commuta
...

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