IEC TS 63042-101:2019

IEC TS 63042-101 ®
Edition 1.0 2019-01
TECHNICAL
SPECIFICATION
colour
inside
UHV AC transmission systems –
Part 101: Voltage regulation and insulation design

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IEC TS 63042-101 ®
Edition 1.0 2019-01
TECHNICAL
SPECIFICATION
colour
inside
UHV AC transmission systems –
Part 101: Voltage regulation and insulation design

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.01 ISBN 978-2-8322-6456-0

– 2 – IEC TS 63042-101:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Reactive power compensation for UHV AC transmission systems . 8
4.1 General principles . 8
4.2 Configuration of reactive power compensation – consider placing after
general functions . 8
4.3 Determining reactive power compensation . 9
4.3.1 Reactive compensation at UHV side . 9
4.3.2 Compensation at tertiary side of UHV transformers . 9
4.3.3 Reactive power compensation at UHV side . 10
4.3.4 Shunt capacitor configuration at tertiary side of UHV transformers. 11
4.3.5 Shunt reactor configuration at tertiary side of UHV transformers . 12
4.4 Controllable shunt reactor at UHV side . 13
4.4.1 General . 13
4.4.2 Capacity selection . 13
4.4.3 Tap-changer . 13
4.4.4 Response speed of CSR . 13
4.4.5 Control mode . 14
4.5 Other requirements for compensation at tertiary side of UHV transformers . 14
4.5.1 Configuration of shunt compensator banks . 14
4.5.2 Connection . 14
4.5.3 Dynamic reactive compensation . 14
5 Voltage regulation . 15
5.1 General . 15
5.2 Voltage regulation for UHV transformers . 15
5.2.1 Voltage regulation via transformer tap changes . 15
5.2.2 Selection of transformer taps . 15
5.2.3 Voltage selection for transformers . 15
5.2.4 Types of tap-changers . 15
5.2.5 UHV transformer tap range . 15
5.2.6 Selection of transformer tap position during operation . 15
6 Generator reactive power control . 16
6.1 General . 16
6.2 Coordination among reactive devices . 17
7 Insulation design and coordination procedure for transmission line and substation
design . 17
7.1 General . 17
7.2 Insulation design procedure . 18
7.3 UHV AC system overvoltage . 18
7.3.1 General . 18
7.3.2 Temporary overvoltage (TOV) . 19
7.3.3 Switching overvoltage (slow-front overvoltage) . 19
7.3.4 Lightning overvoltage (fast-front overvoltage) . 20
7.3.5 Very fast front overvoltage (VFFO) . 21

7.4 Reduction of insulation levels using overvoltage suppression measures . 21
7.4.1 General . 21
7.4.2 Overvoltage suppression using surge arrester with low protective level . 21
7.4.3 Resistor-fitted circuit-breakers with closing/opening resistor . 21
7.4.4 Damping effect of resistor-fitted disconnectors employed in GIS to

suppress VFFO. 22
7.4.5 Damping effect of AIS for suppressing VFFO . 22
7.4.6 Fast insertion of switchable or controllable shunt reactors . 22
7.4.7 Controlled switching . 22
7.5 Coordination of design requirements . 22
7.5.1 General . 22
7.5.2 Transmission line. 22
7.5.3 Substation . 23
Annex A (informative) UHV multi-stage controllable shunt reactor . 24
Annex B (informative) General procedure for the selection of transformer tap positions . 26
Bibliography . 29

Figure 1 – Flowchart for reactive power compensation configuration . 9
Figure 2 – Flow chart for rational insulation specification for UHV . 18
Figure 3 – Overvoltage categorized by time domain . 18
Figure 4 – Overvoltage mechanism caused by back-flashover and direct lightning . 20
Figure A.1 – Illustrative example of a UHV project with an MCSR . 24
Figure B.1 – Schematic diagram of UHV transmission line . 26
Figure B.2 – Voltage profile of UHV line A-B while energized at substation . 27

Table A.1 – Impact of MSCR switching on voltage at station B . 25
Table B.1 – Lower limits of operating voltage for UHV substations . 28

– 4 – IEC TS 63042-101:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UHV AC TRANSMISSION SYSTEMS –
Part 101: Voltage regulation and insulation design

FOREWORD
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