Determination of power losses in high-voltage direct current (HVDC) converter stations with line-commutated converters (IEC 61803:2020)

This document applies to all line-commutated high-voltage direct current (HVDC) converter
stations used for power exchange (power transmission or back-to-back installation) in utility
systems. This document presumes the use of 12-pulse thyristor converters but can, with due
care, also be used for 6-pulse thyristor converters.
In some applications, synchronous compensators or static var compensators (SVC) may be
connected to the AC bus of the HVDC converter station. The loss determination procedures
for such equipment are not included in this document.
This document presents a set of standard procedures for determining the total losses of an
HVDC converter station. The procedures cover all parts, except as noted above, and address
no-load operation and operating losses together with their methods of calculation which use,
wherever possible, measured parameters.
Converter station designs employing novel components or circuit configurations compared to
the typical design assumed in this document, or designs equipped with unusual auxiliary
circuits that could affect the losses, are assessed on their own merits.

Bestimmung der Leistungsverluste in Hochspannungsgleichstrom- (HGÜ-)Stromrichterstationen mit netzgeführten Stromrichtern (IEC 61803:2020)

Détermination des pertes en puissance dans les postes de conversion en courant continu à haute tension (CCHT) munis de convertisseurs commutés par la ligne (IEC 61803:2020)

IEC 61803:2020 est disponible sous forme de IEC 61803:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.

L'IEC 61803:2020 s'applique à tous les postes de conversion en courant continu à haute tension (CCHT), commutés par la ligne, et utilisés pour l'échange de puissance (transmission de puissance ou installation dos à dos) dans des systèmes de distribution d'énergie. Le présent document présuppose l'utilisation de convertisseurs à thyristors à 12 impulsions mais peut également, en prenant les précautions appropriées, s'appliquer à des convertisseurs à thyristors à 6 impulsions. Dans certaines applications, il est admis de connecter des compensateurs synchrones ou des compensateurs var statiques (CVS) au nœud à courant alternatif du poste de conversion en courant continu à haute tension (CCHT). Les procédures de détermination de pertes pour ce type de matériel ne figurent pas dans le présent document. Le présent document décrit un ensemble de procédures types permettant de déterminer l'ensemble des pertes d'un poste de conversion à CCHT. Les procédures s’appliquent à toutes les pièces, à l'exception de celles susmentionnées, et considèrent les pertes en fonctionnement à vide et les pertes en fonctionnement ainsi que leurs méthodes de calcul utilisant, dans la mesure du possible, des paramètres mesurés. Les conceptions de poste de conversion utilisant des composants ou des configurations de circuit originaux par rapport à la conception type prise pour hypothèse dans le présent document, ou des conceptions équipées de circuits de distribution d'énergie auxiliaires inhabituels susceptibles de modifier les pertes, sont évaluées selon leurs propres mérites. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- en vue de faciliter l’application de la norme sans en détériorer la qualité, 5.1.8 et 5.8 ont été revus en tenant compte du fait que la technologie de production de thyristors actuelle occasionne considérablement moins de dispersion dans ses paramètres par rapport à la situation de 1999, lorsque la première édition de l'IEC 61803 a été élaborée. Ainsi, les données enregistrées de production de thyristors peuvent être utilisées pour les calculs de pertes de puissance;
- le calcul des pertes de charge au poste totales (cas D1 et D2 à l’Annexe C) a été corrigé.

Ugotavljanje močnostnih izgub v visokonapetostnih enosmernih (HVDC) pretvorniških postajah s pretvorniki s komutiranjem (IEC 61803:2020)

General Information

Status
Published
Public Enquiry End Date
12-Apr-2020
Publication Date
23-Dec-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
09-Dec-2020
Due Date
13-Feb-2021
Completion Date
24-Dec-2020

Relations

Buy Standard

Standard
EN IEC 61803:2021
English language
40 pages
sale 10% off
Preview
sale 10% off
Preview
e-Library read for
1 day
Draft
prEN IEC 61803:2020
English language
33 pages
sale 10% off
Preview
sale 10% off
Preview
e-Library read for
1 day

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 61803:2021
01-februar-2021
Nadomešča:
SIST EN 61803:2001
SIST EN 61803:2001/A1:2011
SIST EN 61803:2001/A2:2016
Ugotavljanje močnostnih izgub v visokonapetostnih enosmernih (HVDC)
pretvorniških postajah s pretvorniki s komutiranjem (IEC 61803:2020)
Determination of power losses in high-voltage direct current (HVDC) converter stations
with line-commutated converters (IEC 61803:2020)
Bestimmung der Leistungsverluste in Hochspannungsgleichstrom-
(HGÜ-)Stromrichterstationen mit netzgeführten Stromrichtern (IEC 61803:2020)
Détermination des pertes en puissance dans les postes de conversion en courant
continu à haute tension (CCHT) munis de convertisseurs commutés par la ligne (IEC
61803:2020)
Ta slovenski standard je istoveten z: EN IEC 61803:2020
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
SIST EN IEC 61803:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN IEC 61803:2021

---------------------- Page: 2 ----------------------
SIST EN IEC 61803:2021


EUROPEAN STANDARD EN IEC 61803

NORME EUROPÉENNE

EUROPÄISCHE NORM
December 2020
ICS 29.200 Supersedes EN 61803:1999 and all of its amendments
and corrigenda (if any)
English Version
Determination of power losses in high-voltage direct current
(HVDC) converter stations with line-commutated converters
(IEC 61803:2020)
Détermination des pertes en puissance dans les postes de Bestimmung der Leistungsverluste in
conversion en courant continu à haute tension (CCHT) Hochspannungsgleichstrom- (HGÜ-)Stromrichterstationen
munis de convertisseurs commutés par la ligne mit netzgeführten Stromrichtern
(IEC 61803:2020) (IEC 61803:2020)
This European Standard was approved by CENELEC on 2020-11-23. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 61803:2020 E

---------------------- Page: 3 ----------------------
SIST EN IEC 61803:2021
EN IEC 61803:2020 (E)
European foreword
The text of document 22F/563/CDV, future edition 2 of IEC 61803, prepared by SC 22F "Power
electronics for electrical transmission and distribution systems" of IEC/TC 22 "Power electronic
systems and equipment" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 61803:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-08-23
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-11-23
document have to be withdrawn
This document supersedes EN 61803:1999 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 61803:2020 was approved by CENELEC as a European
Standard without any modification.
2

---------------------- Page: 4 ----------------------
SIST EN IEC 61803:2021
EN IEC 61803:2020 (E)
Annex ZA
(normative)

Normative references to international publications with their
corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60076-1 - Power transformers - Part 1: General EN 60076-1 -
IEC 60076-6 - Power transformers - Part 6: Reactors EN 60076-6 -
IEC 60633 - High-voltage direct current (HVDC) EN IEC 60633 -
transmission - Vocabulary
IEC 60700-1 2015 Thyristor valves for high voltage direct EN 60700-1 2015
current (HVDC) power transmission - Part 1:
Electrical testing
IEC 60871-1 - Shunt capacitors for a.c. power systems EN 60871-1 -
having a rated voltage above 1 000 V -
Part 1: General

3

---------------------- Page: 5 ----------------------
SIST EN IEC 61803:2021

---------------------- Page: 6 ----------------------
SIST EN IEC 61803:2021



IEC 61803

®


Edition 2.0 2020-10




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Determination of power losses in high-voltage direct current (HVDC) converter

stations with line-commutated converters



Détermination des pertes en puissance dans les postes de conversion

en courant continu à haute tension (CCHT) munis de convertisseurs commutés

par la ligne















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.200 ISBN 978-2-8322-8948-8




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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 7 ----------------------
SIST EN IEC 61803:2021
– 2 – IEC 61803:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and symbols. 6
3.1 Terms and definitions . 7
3.2 Symbols . 8
4 Overview . 8
4.1 General . 8
4.2 Ambient conditions. 9
4.2.1 General . 9
4.2.2 Outdoor standard reference temperature . 9
4.2.3 Coolant standard reference temperature . 9
4.2.4 Standard reference air pressure . 10
4.3 Operating parameters . 10
5 Determination of equipment losses . 10
5.1 Thyristor valve losses . 10
5.1.1 General . 10
5.1.2 Thyristor conduction loss per valve . 11
5.1.3 Thyristor spreading loss per valve . 12
5.1.4 Other conduction losses per valve . 12
5.1.5 DC voltage-dependent loss per valve . 13
5.1.6 Damping loss per valve (resistor-dependent term) . 14
5.1.7 Damping loss per valve (change of capacitor energy term) . 14
5.1.8 Turn-off losses per valve . 15
5.1.9 Reactor loss per valve . 15
5.1.10 Total valve losses . 16
5.1.11 Temperature effects. 16
5.1.12 No-load operation loss per valve . 16
5.2 Converter transformer losses . 17
5.2.1 General . 17
5.2.2 No-load operation losses . 17
5.2.3 Operating losses. 17
5.2.4 Auxiliary power losses . 18
5.3 AC filter losses . 19
5.3.1 General . 19
5.3.2 AC filter capacitor losses . 19
5.3.3 AC filter reactor losses . 19
5.3.4 AC filter resistor losses . 20
5.3.5 Total AC filter losses . 20
5.4 Shunt capacitor bank losses . 20
5.5 Shunt reactor losses . 20
5.6 DC smoothing reactor losses . 21
5.7 DC filter losses . 21
5.7.1 General . 21
5.7.2 DC filter capacitor losses . 22
5.7.3 DC filter reactor losses . 22

---------------------- Page: 8 ----------------------
SIST EN IEC 61803:2021
IEC 61803:2020 © IEC 2020 – 3 –
5.7.4 DC filter resistor losses . 23
5.7.5 Total DC filter losses . 23
5.8 Auxiliaries and station service losses . 23
5.9 Series filter losses . 24
5.10 Other equipment losses . 25
Annex A (informative) Calculation of harmonic currents and voltages . 31
A.1 Harmonic currents in converter transformers . 31
A.2 Harmonic currents in the AC filters . 31
A.3 Harmonic voltages on the DC side . 32
A.4 DC side harmonic currents in the smoothing reactor . 32
Annex B (informative) Typical station losses . 33
Annex C (informative) HVDC converter station loss evaluation – An illustration . 34
C.1 General . 34
C.2 Loss evaluation under various cases . 35
Bibliography . 37

Figure 1 – Typical high-voltage direct current (HVDC) equipment for one pole . 26
Figure 2 – Simplified three-phase diagram of an HVDC 12-pulse converter . 27
Figure 3 – Simplified equivalent circuit of a typical thyristor valve . 27
Figure 4 – Current and voltage waveforms of a valve operating in a 12-pulse converter . 28
Figure 5 – Thyristor on-state characteristic . 29
Figure 6 – Conduction current and voltage drop . 29
Figure 7 – Distribution of commutating inductance between L and L . 30
1 2
Figure 8 – Thyristor current during reverse recovery . 30

Table B.1 – Typical values of losses . 33
Table C.1 – Conditions for calculation of losses in case D1 . 36
Table C.2 – Conditions for calculation of losses in Case D2. . 36

---------------------- Page: 9 ----------------------
SIST EN IEC 61803:2021
– 4 – IEC 61803:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

DETERMINATION OF POWER LOSSES IN HIGH-VOLTAGE
DIRECT CURRENT (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,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC
Publication(s)"). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
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
Publications.
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.
International Standard IEC 61803 has been prepared by subcommittee 22F: Power electronics
for electrical transmission and distribution systems, of IEC technical committee 22: Power
electronic systems and equipment.
This second edition cancels and replaces the first edition published in 1999,
Amendment 1:2010 and Amendment 2:2016. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) to facilitate the application of this document and to ensure its quality remains consistent,
5.1.8 and 5.8 have been reviewed, taking into consideration that the present thyristor
production technology provides considerably less thyristor parameters dispersion
comparing with the situation in 1999 when the first edition of IEC 61803 was developed,
and therefore the production records of thyristors can be used for the power losses
calculation;

---------------------- Page: 10 ----------------------
SIST EN IEC 61803:2021
IEC 61803:2020 © IEC 2020 – 5 –
b) the calculation of the total station load losses (cases D1 and D2 in Annex C) has been
corrected.
The text of this International Standard is based on the following documents:
CDV Report on voting
22F/563/CDV 22F/580A/RVC

Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
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.

---------------------- Page: 11 ----------------------
SIST EN IEC 61803:2021
– 6 – IEC 61803:2020 © IEC 2020
DETERMINATION OF POWER LOSSES IN HIGH-VOLTAGE
DIRECT CURRENT (HVDC) CONVERTER STATIONS WITH
LINE-COMMUTATED CONVERTERS



1 Scope
This document applies to all line-commutated high-voltage direct current (HVDC) converter
stations used for power exchange (power transmission or back-to-back installation) in utility
systems. This document presumes the use of 12-pulse thyristor converters but can, with due
care, also be used for 6-pulse thyristor converters.
In some applications, synchronous compensators or static var compensators (SVC) may be
connected to the AC bus of the HVDC converter station. The loss determination procedures
for such equipment are not included in this document.
This document presents a set of standard procedures for determining the total losses of an
HVDC converter station. The procedures cover all parts, except as noted above, and address
no-load operation and operating losses together with their methods of calculation which use,
wherever possible, measured parameters.
Converter station designs employing novel components or circuit configurations compared to
the typical design assumed in this document, or designs equipped with unusual auxiliary
circuits that could affect the losses, are assessed on their own merits.
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 60076-1, Power transformers – Part 1: General
IEC 60076-6, Power transformers – Part 6: Reactors
IEC 60633, High-voltage direct current (HVDC) transmission – Vocabulary
IEC 60700-1:2015, Thyristor valves for high voltage direct current (HVDC) power transmission
– Part 1: Electrical testing
IEC 60871-1, Shunt capacitors for a.c. power systems having a rated voltage above 1 000 V –
Part 1: General
3 Terms, definitions and symbols
For the purposes of this document, the terms and definition given in IEC 60633 and the
following apply.

---------------------- Page: 12 ----------------------
SIST EN IEC 61803:2021
IEC 61803:2020 © IEC 2020 – 7 –
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
3.1 Terms and definitions
3.1.1
auxiliary losses
electric power required to feed the converter station auxiliary loads
Note 1 to entry: The auxiliary losses depend on the number of converter units used and whether the station is in
no-load operation or carrying load, in which case the auxiliary losses depend on the load level.
3.1.2
equipment no-load operation losses
losses produced in an item of equipment with the converter station energised but with the
converters blocked and all station service loads and auxiliary equipment connected as
required for immediate pick-up of load to specified minimum power
3.1.3
load level
direct current, direct voltage, firing angle, AC voltage, and converter transformer tap-changer
position at which the converter station is operating
3.1.4
equipment operating losses
losses produced in an item of equipment at a given load level with the converter station
energised and the converters operating
3.1.5
rated load
load related to operation at nominal values of DC current, DC voltage, AC voltage and
converter firing angle
Note 1 to entry: The AC system shall be assumed to be at nominal frequency, and its 3-phase voltages are
nominal and balanced. The position of the tap-changer of the converter transformer and the number of AC filters
and shunt reactive elements connected shall be consistent with operation at rated load, coincident with nominal
conditions.
3.1.6
total station no-load operation losses
sum of all equipment no-load operation losses (3.1.2) and corresponding auxiliary losses
(3.1.1)
3.1.7
total station operating losses
sum of all equipment operating losses (3.1.4) and corresponding auxiliary losses (3.1.1) at a
particular load level
Note 1 to entry: An illustrative example using total station operating losses and corresponding loss evaluation is
given in Annex C, case D1.
3.1.8
total station load losses
difference between total station operating losses (3.1.7) and total station no-load operation
losses (3.1.6)
Note 1 to entry: Such calculated total station load losses are considered as being quantitatively equivalent to load
losses as in conventional AC substation practice.

---------------------- Page: 13 ----------------------
SIST EN IEC 61803:2021
– 8 – IEC 61803:2020 © IEC 2020
Note 2 to entry: It is recognized that some purchasers evaluate total station no-load operation losses (3.1.6) and
total station load losses individually instead of the evaluating total station operating losses (3.1.7).
Note 3 to entry: An illustrative example to derive load losses, equivalent load losses and corresponding loss
evaluation is given in Annex C, case D2.
3.1.9
station essential auxiliary load
load whose failure will affect the conversion capability of the HVDC converter station (e.g.
valve cooling), as well as load that shall remain working in case of complete loss of AC power
supply (e.g. battery chargers, operating mechanisms)
3.2 Symbols
α (trigger/firing) delay angle, in radians (rad)
overlap angle, in radians (rad)
µ
f AC system frequency, in hertz (Hz)
I direct current, in amperes (A)
d
I harmonic RMS current of order n, in amperes (A)
n
L inductance, in henrys (H), referred to the valve winding, between the commutating
1
voltage source and the point of common coupling between star- and delta-connected
windings. L shall include any external inductance between the transformer line-
1
winding terminals and the point of connection of the AC harmonic filters.
L inductance, in henrys (H), referred to the valve winding, between the point of
2
common coupling between star- and delta-connected windings, and the valve. L
2
shall include the saturated inductance of the valve reactors.
m
electromagnetic notch coupling factor, m = L /(L + L )
1 1 2
n harmonic order
N number of series-connected thyristors per valve
t
P power loss in an item of equipment, in watts (W)
Q
quality factor at harmonic order n
n
R
resistance value, in ohms (Ω)
U direct voltage, in volts (V)
d
U
harmonic RMS voltage of order n, in volts (V)
n
U RMS value of the phase-to-phase no-load voltage on the valve side of the converter
vo
transformer excluding harmonics, in volts (V)
X
inductive reactance at harmonic order n, in ohms (Ω)
n

4 Overview
4.1 General
Suppliers need to know in detail how and where losses are generated, since this affects
component and equipment ratings. Purchasers are interested in a verifiable loss figure which
allows equitable bid comparison and in a procedure after delivery which can objectively verify
the guaranteed performance requirements of the supplier.

---------------------- Page: 14 ----------------------
SIST EN IEC 61803:2021
IEC 61803:2020 © IEC 2020 – 9 –
As a general principle, it would be desirable to determine the efficiency of an HVDC converter
station by a direct measurement of its energy losses. However, attempts to determine the
station losses by subtracting the measured output power from the measured input power
should recognize that such measurements have an inherent inaccuracy, especially if
performed at high voltage. The losses of an HVDC converter station at full load are generally
less than 1 % of the transmitted power. Therefore, the loss measured as a small difference
between two large quantities is not likely to be a sufficiently accurate indication of the actual
losses.
In some special circumstances, it may be possible, for example, to arrange a temporary test
connection in which two converters are operated from the same AC source and also
connected together via their DC terminals. In this connection, the power drawn from the AC
source equals the losses in the circuit. However, the AC source shall also provide var support
and commutating voltage to the two converters. Once again, there are practical measurement
difficulties.
In order to avoid the problems described above, this document standardizes a method of
calculating the HVDC converter station losses by summing the losses calculated for each item
of equipment. The standardized calculation method will help the purchaser to mean
...

SLOVENSKI STANDARD
oSIST prEN IEC 61803:2020
01-april-2020
Ugotavljanje močnostnih izgub v visokonapetostnih enosmernih (HVDC)
pretvorniških postajah s pretvorniki s komutiranjem
Determination of power losses in high-voltage direct current (HVDC) converter stations
with line-commutated converters
Bestimmung der Leistungsverluste in Hochspannungsgleichstrom-
(HGÜ-)Stromrichterstationen mit netzgeführten Stromrichtern
Détermination des pertes en puissance dans les postes de conversion en courant
continu à haute tension (CCHT) munis de convertisseurs commutés par le réseau
Ta slovenski standard je istoveten z: prEN IEC 61803:2020
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
oSIST prEN IEC 61803:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN IEC 61803:2020

---------------------- Page: 2 ----------------------
oSIST prEN IEC 61803:2020
22F/563/CDV

COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61803 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2020-01-24 2020-04-17
SUPERSEDES DOCUMENTS:
22F/530/CD, 22F/542A/CC

IEC SC 22F : POWER ELECTRONICS FOR ELECTRICAL TRANSMISSION AND DISTRIBUTION SYSTEMS
SECRETARIAT: SECRETARY:
Russian Federation  Mr. Lev TRAVIN
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

TC 115
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:

EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which
they are aware and to provide supporting documentation.

TITLE:
Determination of power losses in high-voltage direct current (HVDC) converter stations with line-commutated
converters

PROPOSED STABILITY DATE: 2024

NOTE FROM TC/SC OFFICERS:
This CDV document, based on documents 22F/530/CD and 22F/542A/CC, was developed in accordance with
the decision taken at SC 22F plenary meeting in Shanghai, China, on October 21-23, 2019 (see 22F/560/DL,
Decision 2019-07, Action 2019-03).

Copyright © 2020 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of prepari ng National Committee
positions. You may not copy or "mirror" the file or printed version of theocument, or any part of it, for any other purpose
without permission in writing from IEC.

---------------------- Page: 3 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 2 -                          22F/563/CDV

1 CONTENTS
2 FOREWORD………………………………………………………………………………………….- 4 -
3 1 Scope. - 5 -
4 2 Normative references . - 5 -
5 3 Definitions and symbols . - 5 -
6 3.1 Definitions . - 6 -
7 3.2 Letter symbols . - 7 -
8 4 General . - 7 -
9 4.1 Introduction . - 7 -
10 4.2 Ambient conditions . - 8 -
11 4.3 Operating parameters . - 8 -
12 5 Determination of equipment losses . - 9 -
13 5.1 Thyristor valve losses . - 9 -
14 5.2 Converter transformer losses . - 14 -
15 5.3 AC filter losses . - 15 -
16 5.4 Shunt capacitor bank losses . - 17 -
17 5.5 Shunt reactor losses . - 17 -
18 5.6 DC smoothing reactor losses . - 17 -
19 5.7 DC filter losses . - 18 -
20 5.8 Auxiliaries and station service losses . - 19 -
21 5.9 Series filter losses . - 20 -
22 5.10 Other equipment losses . - 20 -
23 Annex A    (normative)  Calculation of harmonic currents and voltages…………….….- 28 -
24 A.1 Harmonic currents in converter transformers………………………………………….- 28 -
25 A.2 Harmonic currents in the a.c. filters……………………………………………….…… - 28 -
26 A.3 Harmonic voltages on the d.c. side…………………………………………………… - 29 -
27 A.4 DC side harmonic currents in the smoothing reactor………………………………… - 29 -
28 Annex B    (informative)  Typical station losses……………………………………………… - 30 -
29 Annex C    (informative) HVDC converter station loss evaluation – An illustration……. - 31 -
30 Annex D    (informative)  Bibliography…….;…………………………………………………. - 33 -
31 C.1  General……………………………………………………………………………………… - 31 -
32 C.2 Loss evaluation under various cases…………………………………………………… - 32 -
33 Figure 1 – Typical high-voltage direct current (HVDC) equipment for one pole . .- 22 -
34 Figure 2 – Simplified three-phase diagram of an HVDC 12-pulse converter . .- 23 -
35 Figure 3 – Simplified equivalent circuit of a typical thyristor valve . .- 23 -
36 Figure 4a – Rectifier operation . .- 24 -
37 Figure 4b – Inverter operation . .- 24 -
38 Figure 4 – Current and voltage waveforms of a valve operating in a 12-pulse converter
39 (commutation overshoots are not shown) . .- 24 -
40 Figure 5 – Thyristor on-state characteristic . .- 25 -
41 Figure 6a – Conduction current . .- 25 -
42 Figure 6b – Voltage drop across an ideal thyristor A or a real thyristor B . .- 25 -
43 Figure 6 – Conduction current and voltage drop . .- 25 -
44 Figure 7 – Distribution of commutating inductance between L and L . .- 26 -
1 2
45 Figure 8 – Thyristor current during reverse recovery . .- 26 -
46 Table C.1 – Conditions for calculation of losses in Case D1. . .- 32 -
47 Table C.2 – Conditions for calculation of losses in Case D2. . .- 32 -
48

---------------------- Page: 4 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 3 -                           22F/563/CDV

49
50 INTERNATIONAL ELECTROTECHNICAL COMMISSION
51 ––––––––––––
52
53 DETERMINATION OF POWER LOSSES IN HIGH-VOLTAGE
54 DIRECT CURRENT (HVDC) CONVERTER STATIONS WITH LINE-COMMUTATED
55 CONVERTERS
56
57
58 FOREWORD
59 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all
60 national electrotechnical committees (IEC National Committees). The object of IEC is to promote internation al co-
61 operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition
62 to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly
63 Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is
64 entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in
65 this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also
66 participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in
67 accordance with conditions determined by agreement between the two organizations.
68 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
69 consensus of opinion on the relevant subjects since each technical committee has representation from all interested
70 IEC National Committees.
71 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
72 Committees in that sense. W hile all reasonable efforts are made to ensure that the technical content of IEC
73 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
74 misinterpretation by any end user.
75 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
76 transparently to the maximum extent possible in their national and regional publications. Any divergence between any
77 IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
78 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformit y
79 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services
80 carried out by independent certification bodies.
81 6) All users should ensure that they have the latest edition of this publication.
82 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members
83 of its technical committees and IEC National Committees for any personal injur y, property damage or other damage of
84 any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the
85 publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
86 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
87 indispensable for the correct application of this publication.
88 9) Attention is drawn to the possibility that some of the elements of this IEC Public ation may be the subject of patent
89 rights. IEC shall not be held responsible for identifying any or all such patent rights.
90
91 International Standard IEC 61803 has been prepared by subcommittee 22F: POWER
92 ELECTRONICS FOR ELECTRICAL TRANSMISSION AND DISTRIBUTION SYSTEMS, of IEC
93 technical committee 22: POWER ELECTRONIC SYSTEMS AND EQUIPMENT.
94 This second edition cancels and replaces the first edition published in 1999-02-26, Corrigendum
95 1:1999-10-29, Amendment 1:2010-11-25 and Amendment 2:2016-05-25. This edition constitutes a
96 technical revision.
97 This edition includes the following significant technical changes with respect to the previous edition:
98 a) It is taken into account that the present thyristor production technology provides
99 considerably less thyristor parameters dispersion comparing with the situation in 1999 when the
100 standard was developed and therefore the production records of thyristors can be used for the
101 power losses calculation (subclauses 5.1.7 and 5.8).
102 b) The correction is made concerning the calculation of the total station load losses (Cases D1
103 and D2 in Annex C).

---------------------- Page: 5 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 4 -                           22F/563/CDV

104 c) The logical order of clauses, subclauses and annexes of the standard is established.
105 The committee has decided that the contents of the base publication and its amendments will
106 remain unchanged until the stability date indicated on the IEC web site under
107 "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication
108 will be
109 • reconfirmed,
110 • withdrawn,
111 • replaced by a revised edition, or
112 • amended.
113
114
115
116
117
118

---------------------- Page: 6 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 5 -                           22F/563/CDV

119
120 DETERMINATION OF POWER LOSSES IN HIGH-VOLTAGE
121 DIRECT CURRENT (HVDC) CONVERTER STATIONS WITH LINE-COMMUTATED
122 CONVERTERS
123
124 1 Scope
125 This International Standard applies to all line-commutated high-voltage direct current (HVDC)
126 converter stations used for power exchange in utility systems. This standard presumes the use of
127 12-pulse thyristor converters but can, with due care, also be used for 6-pulse thyristor converters.
128 In some applications, synchronous compensators or static var compensators (SVC) may be
129 connected to the a.c. bus of the HVDC converter station. The loss determination procedures for
130 such equipment are not included in this standard.
131 This standard presents a set of standard procedures for determining the total losses of an HVDC
132 converter station. Typical HVDC equipment is shown in figure 1. The procedures cover all parts,
133 except as noted above, and address no-load operation and operating losses together with their
134 methods of calculation which use, wherever possible, measured parameters.
135 Converter station designs employing novel components or circuit configurations compared to the
136 typical design assumed in this standard, or designs equipped with unusual auxiliary circuits that
137 could affect the losses, shall be assessed on their own merits.
138 2 Normative references
139 The following referenced documents are indispensable for the application of this document. For
140 dated references, only the edition cited applies. For undated references, the latest edition of the
141 referenced document (including any amendments) applies.
142 IEC 60076-1, Power transformers – Part 1: General
143 IEC 60076-6, Power transformers – Part 6: Reactors
144 IEC 60633, Terminology for high-voltage direct current (HVDC) transmission
145 IEC 60700-1, Thyristor valves for high voltage direct current (HVDC) power transmission – Part 1:
146 Electrical testing
147 IEC 60747-6, Semiconductor devices Part 6: Thyristors
148 IEC 60871-1, Shunt capacitors for a.c. power systems having a rated voltage above
149 1 000 V – Part 1: General
150 3 Definitions and symbols
151 For the purpose of this International Standard, the following definiti ons apply:

---------------------- Page: 7 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 6 -                           22F/563/CDV

152 3.1 Definitions
153 3.1.1
154 auxiliary losses
155 electric power required to feed the converter station auxiliary loads
156 Note 1 to entry: The auxiliary losses depend on the number of converter units used and whether the statio n is in no-load
157 operation or carrying load, in which case the auxiliary losses depend on the load level.
158 3.1.2
159 equipment no-load operation losses
160 losses produced in an item of equipment with the converter station energised but with the
161 converters blocked and all station service loads and auxiliary equipment connected as required for
162 immediate pick-up of load to specified minimum power
163 3.1.3
164 load level
165 this term specifies the direct current, direct voltage, firing angle, a.c. voltage, and converter
166 transformer tap-changer position at which the converter station is operating
167 3.1.4
168 equipment operating losses
169 the losses produced in an item of equipment at a given load level with the converter station
170 energized and the converters operating
171 3.1.5
172 rated load
173 load related to operation at nominal values of d.c. current, d.c. voltage, a.c. voltage and converter
174 firing angle
175 Note 1 to entry: The a.c. system shall be assumed to be at nominal frequency and its 3-phase voltages are nominal and
176 balanced. The position of the tap-changer of the converter transformer and the number of a.c. filters and shunt reactive
177 elements connected shall be consistent with operation at rated load, coincident with nominal conditions.
178 3.1.6
179 total station no-load operation losses
180 sum of all equipment no-load operation losses (3.1.2) and corresponding auxiliary losses (3.1.1)
181 3.1.7
182 total station operating losses
183 sum of all equipment operating losses (3.1.4) and corresponding auxiliary losses (3.1.1) at a
184 particular load level
185 Note 1 to entry: An illustrative example using “Total station operating losses” and corresponding “loss evaluation” is
186 given in Annex C, Case D1.
187 3.1.8
188 total station load losses
189 total station load losses shall be calculated from the difference between total sta tion operating
190 losses (3.1.7) and total station no-load operation losses (3.1.6).
191 Note 1 to entry: Such calculated “total station load losses” are considered as being quantitatively equivalent to “load
192 losses” as in conventional a.c. substation practice.
193 Note 2 to entry: It is recognised that some purchasers evaluate “Total station no-load operation losses” (definition 3.1.6)
194 and total station load losses individually instead of the evaluating “Total station operating losses” (definition 3.1.7).
195 Note 3 to entry: An illustrative example to derive “load losses”, "equivalent load losses" and corresponding “loss
196 evaluation” is given in Annex C, case D2.
197 3.1.9
198 station essential auxiliary load
199 load whose failure will affect the conversion capability of the HVDC converter station (e.g. valve
200 cooling), as well as load that must remain working in case of complete loss of a.c. power supply
201 (e.g. battery chargers, operating mechanisms)

---------------------- Page: 8 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 7 -                           22F/563/CDV

202 3.2 Letter symbols
203  (trigger/firing) delay angle, in radians (rad)
204  overlap angle, in radians (rad)
205 f a.c. system frequency, in hertz (Hz)
206 I direct current,in amperes (A)
d
207 I harmonic r.m.s. current of order n, in amperes (A)
n
208 L the inductance, in henrys (H), referred to the valve winding, between the commutating volta ge
1
209 source and the point of common coupling between star- and delta-connected windings. L
1
210 shall include any external inductance between the transformer line-winding terminals and the
211 point of connection of the a.c. harmonic filters
212 L the inductance, in henrys (H), referred to the valve winding, between the point of common
2
213 coupling between star- and delta-connected windings, and the valve. L shall include the
2
214 saturated inductance of the valve reactors
215 m electromagnetic notch coupling factor, m = L /(L + L )
1 1 2
216 n harmonic order
217 N the number of series-connected thyristors per valve
t
218 P power loss in an item of equipment, in watts (W)
219 Q quality factor at harmonic order n
n
220 R resistance value, in ohms (
221 U direct voltage, in volts (V)
d
222 U harmonic r.m.s. voltage of order n, in volts (V)
n
223 U r.m.s. value of the phase-to-phase no-load voltage on the valve side of the converter
vo
224 transformer excluding harmonics, in volts (V)
225 X inductive reactance at harmonic order n, in ohms (
n
226 4 General
227 4.1 Introduction
228 Suppliers need to know in detail how and where losses are generated, since this affects component
229 and equipment ratings. Purchasers are interested in a verifiable loss figure which allows equitable
230 bid comparison and in a procedure after delivery which can objectively verify the guaranteed
231 performance requirements of the supplier.
232 As a general principle, it would be desirable to determine the efficiency of an HVDC converter
233 station by a direct measurement of its energy losses. However, attempts to determine the station
234 losses by subtracting the measured output power from the measured input power should recognize
235 that such measurements have an inherent inaccuracy, especially if performed at high voltage.The
236 losses of an HVDC converter station at full load are generally less than 1% of the transmitted
237 power. Therefore, the loss measured as a small difference between two large quantities is not likely
238 to be a sufficiently accurate indication of the actual losses.
239 In some special circumstances it may be possible, for example, to arrange a temporary test
240 connection in which two converters are operated from the same a.c. source and also connected
241 together via their d.c. terminals. In this connection, the power drawn from t he a.c. source equals the
242 losses in the circuit. However, the a.c. source must also provide var support and commutating
243 voltage to the two converters. Once again, there are practical measurement difficulties.
244 In order to avoid the problems described above, this standard standardizes a method of calculating
245 the HVDC converter station losses by summing the losses calculated for each item of equipment.
246 The standardized calculation method will help the purchaser to meaningfully compare the competing
247 bids. It will also allow an easy generation of performance curves for the wide range of operating
248 conditions in which the performance has to be known. In the absence of an inexpensive
249 experimental method which could be employed for an objective verification of losses during type
250 tests, the calculation method is the next best alternative as it uses, wherever possible, experimental

---------------------- Page: 9 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 8 -                           22F/563/CDV

251 data obtained from measurements on individual equipment and components under conditions
252 equivalent to those encountered in real operation.
253 It is important to note that the power loss in each item of equipment will depend on the ambient
254 conditions under which it operates, as well as on the operating conditions or duty cycles to which it
255 is subjected. Therefore, the ambient and operating conditions shall be defined for each item of
256 equipment, based on the ambient and operating conditions of the entire HVDC converter station.
257 4.2 Ambient conditions
258 A set of standard reference ambient conditions shall be used for determining the power losses in
259 HVDC converter stations.
260 4.2.1 Outdoor standard reference temperature
261 An outdoor ambient dry bulb temperature of 20 °C shall be used as the standard reference
262 temperature for determining the total converter station losses. Corresponding valve hall temperature
263 may be defined by the supplier if necessary. The equivalent wet-bulb temperature (where
264 necessary) shall be defined by the purchaser.
265 NOTE If not defined, the wet-bulb temperature is recommended to be 14 °C which corresponds to approximately 50 %
266 RH at 20 °C dry bulb temperature.
267 4.2.2 Coolant standard reference temperature
268 Where forced cooling is used for equipment, the flow rate and temperature of the coolant can
269 influence the temperature rise and associated losses of that equipment. Therefore, the coolant
270 temperatures and flow rates established by the purchaser and the supplier shall be used as a basis
271 for determining the losses.
272 4.2.3 Standard reference air pressure
273 The reference air pressure to be used for the evaluation of total converter station power losses shall
274 be the standard atmospheric pressure (101,3 kPa) corrected to the altitude of the installation in
275 question.
276 4.3 Operating parameters
277 The losses of an HVDC converter station depend on its operating parameters.
278 The losses of HVDC converter stations are classified into two categories, referred to as operating
279 losses (3.1.4 and 3.1.7) and no-load operation losses (3.1.2 and 3.1.6).
280 The operating losses and auxiliary losses are affected by the load level of the station because the
281 numbers of certain types of energized equipment (for example harmonic filters and cooling
282 equipment) may depend upon the load level and because losses in individual items of equipment
283 themselves vary with the load level.
284 HVDC converter station losses shall be determined for nominal (balanced) a.c. system voltage and
285 frequency, symmetrical impedances of the converter transformer and symmetrical firing angles. The
286 transformer tap-changer shall be assumed to be in the position corresponding to nominal a.c.
287 system voltage or as decided by the control system for the defined operating condition.
288 The operating losses shall be determined for the load levels specified by the purchaser, or at rated
289 load if no such conditions are specified. For each load level, the valve-winding a.c. voltage, d.c.
290 current, converter firing angle, shunt compensation and harmonic filtering equipment shall be
291 consistent with the respective load level and other specified performance requirements, relating, for
292 example, to harmonic distortion and reactive power. Cooling and other auxiliary equipment, as
293 appropriate to the standard reference temperature (see 4.2.1 and 4.2.2), shall be assumed to be
294 connected to support the respective load level.

---------------------- Page: 10 ----------------------
oSIST prEN IEC 61803:2020
61803/Ed2/CDV  IEC (E)                  - 9 -                           22F/563/CDV

295 For the no-load operation mode, converter transformers shall be energized and the converters
296 blocked. All filters and reactive power compensation equipment shall be assumed to be
297 disconnected except for those which are required to sustain operation at zero load in order, for
298 example, to meet the specified reactive power requirements. Station service loads and auxiliary
299 equipment (e.g. cooling-water pumps) shall be assumed to be connected as required for immediate
300 pick-up of load for the converter station (without waiting for tap changer movement) to specified
301 minimum power.
302 5 Determination of equipment losses
303 5.1 Thyristor valve losses
304 The loss production mechanisms applicable when the valves are blocked (no-load operation losses)
305 are different from those applicable in normal operation (operating losses). Operating losses are
306 dealt with in subclauses 5.1.1 to 5.1.10, and no-load operation losses are dealt with in 5.1.11.
307 Auxiliary losses are dealt with in 5.8.
308 A simplified three-phase diagram of an HVDC 12-pulse converter is shown in figure 2. Individual
309 valves are marked in the order of their conduction sequence.
310 A simplified equivalent circuit of a typical valve is shown in figure 3. Symbol th combines together
311 the effects of N thyristors connected in series in the valve. C and R are the corresponding
t AC AC
312 combined values of R-C damping circuits used for voltage sharing and overvoltage suppression.
313 R represents d.c. grading resistors and other resistive components which incur loss when the
DC
314 valve blocks voltage. It also includes the effects of the thyristor leakage current (see 5.1.4 and
315 5.1.11). C includes both stray capacitances and surge distribution capacitors (if used). L
s s
316 represents saturable reactors used to limit the di/dt stresses to safe values and to improve the
317 distribution of fast rising voltages. R represents the resistances of the current conducting
s
318 components of the valve such as the busbars, contact resistances, resistance of the windings of the
319 saturable reactors etc. Power losses in the valve surge arrester (not shown) shall be neglected.
320 Figure 4 show
...

Questions, Comments and Discussion

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