EN 62751-2:2014/A1:2019

SLOVENSKI STANDARD
01-januar-2020
Ugotavljanje izgub moči v napetostnih pretvorniških ventilih za visokonapetostne
enosmerne sisteme - 2. del: Modularni večnivojski pretvorniki (IEC 62751-
2:2014/A1:2019)
Power losses in voltage sourced converter (VSC) valves for high-voltage direct current
(HVDC) systems - Part 2: Modular multilevel converters (IEC 62751-2:2014/A1:2019)
Bestimmung der Leistungsverluste in Spannungszwischenkreis-Stromrichtern (VSC) für
Hochspannungsgleichstrom(HGÜ)-Systeme - Teil 2: Modulare Mehrpunkt-Stromrichter
(IEC 62751-2:2014/A1:2019)
Pertes de puissance dans les valves à convertisseur de source de tension (VSC) des
systèmes en courant continu à haute tension (CCHT) - Partie 2: Convertisseurs
multiniveaux modulaires (IEC 62751-2:2014/A1:2019)
Ta slovenski standard je istoveten z: EN 62751-2:2014/A1:2019
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
29.240.01 Omrežja za prenos in Power transmission and
distribucijo električne energije distribution networks in
na splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 62751-2:2014/A1

NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2019
ICS 29.200; 29.240
English Version
Power losses in voltage sourced converter (VSC) valves for
high-voltage direct current (HVDC) systems - Part 2: Modular
multilevel converters
(IEC 62751-2:2014/A1:2019)
Pertes de puissance dans les valves à convertisseur de Bestimmung der Leistungsverluste in
source de tension (VSC) des systèmes en courant continu Spannungszwischenkreis-Stromrichtern (VSC) für
à haute tension (CCHT) - Partie 2: Convertisseurs Hochspannungsgleichstrom(HGÜ)-Systeme - Teil 2:
multiniveaux modulaires Modulare Mehrpunkt-Stromrichter
(IEC 62751-2:2014/A1:2019) (IEC 62751-2:2014/A1:2019)
This amendment A1 modifies the European Standard EN 62751-2:2014; it was approved by CENELEC on 2019-09-27. CENELEC
members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this amendment 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 amendment 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
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 62751-2:2014/A1:2019 E

European foreword
The text of document 22F/479/CDV, future IEC 62751-2/A1, 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
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-06-27
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-09-27
document have to be withdrawn
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 62751-2:2014/A1:2019 was approved by CENELEC as a
European Standard without any modification.

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 61803 -  Determination of power losses in high- EN 61803 -
voltage direct current (HVDC) converter
stations
IEC 62751-2 ®
Edition 1.0 2019-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
A MENDMENT 1
AM ENDEMENT 1
Power losses in voltage sourced converter (VSC) valves for high-voltage direct

current (HVDC) systems –
Part 2: Modular multilevel converters

Pertes de puissance dans les valves à convertisseur de source de tension (VSC)

des systèmes en courant continu à haute tension (CCHT) –

Partie 2: Convertisseurs multiniveaux modulaires

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.200; 29.240 ISBN 978-2-8322-7218-3

– 2 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
FOREWORD
This amendment has been prepared by subcommittee 22F: Power electronics for electrical
transmission and distribution systems, of IEC technical committee 22: Power electronic
systems and equipment.
The text of this amendment is based on the following documents:
CDV Report on voting
22F/479/CDV 22F/488B/RVC
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC website under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
_____________
2 Normative references
Add the following new reference:
IEC 61803, Determination of power losses in high-voltage direct current (HVDC) converter
stations
3.1.11
no-load operating state
Add, after the existing definition, the following new note:
Note 1 to entry: In the no-load state, in principle no switching should occur as the valve is blocked. However, in
some designs, it may be necessary to make occasional switching operations to balance voltages between different
parts of the converter. Here, some losses may occur and need to be accounted for.

IEC 62751-2:2014/AMD1:2019 – 3 –
© IEC 2019
4 General conditions
4.1 General
Replace, in the third sentence of the existing paragraph, the abbreviated term "CTLC" by
"CTL".
4.2 Principles for loss determination
Add, to the end of the first existing paragraph, the following new sentence:
The manufacturer shall justify, in the loss calculation report, how the uncertainties have been
considered.
Replace the last two sentences of the third existing paragraph by the following new sentences:
In practice, this measurement would require the use of state-of-the-art measurement
equipment that rivals the best equipment available at national metrology institutes. To date,
although some industry/academic partnership projects have demonstrated prototypes of
measurement equipment claiming sufficient accuracy, there is little industry experience with
using such equipment on site. The feasibility of using laboratory measurements on VSC
valves to support a more accurate determination of valve losses is now under study in
CIGRÉ WG B4-75.
4.4 Loss calculation method
Replace the first sentence of the existing second paragraph by the following new sentence:
An important requirement for such simulations is an accurate modelling of the system under
investigation.
4.5.2 Input data for numerical simulations
Replace the last item of the existing dash list by the following new items:
– For calculating converter valve currents and MMC building block capacitor currents, which
are the basis for the calculation of corresponding losses, it is sufficient to use a simplified
model in which the on-state and switching characteristics of the IGBTs and diodes are
represented by worst-case characteristics applicable to their maximum rated junction
temperature.
– For the detailed calculation of losses, the simulation shall also consider the junction
temperature dependent semiconductor properties, such as on-state voltages, switching
and recovery losses. These properties are based on the characterisation testing as
described in IEC 62751-1:2014, 4.4.2. The steady-state junction temperatures of the
semiconductors are calculated iteratively for the relevant operating point to derive the
semiconductor losses.
4.5.3 Input data coming from numerical simulations
Add, to the last existing paragraph, the following new sentence:
The mean and rms currents in IGBTs and diodes are not required if conduction losses in
IGBTs and diodes are calculated using polynomials as discussed in 5.1.
4.5.4 Converter station data
Add, to the sixth dash of the existing list, the words "(for CTL designs)".

– 4 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
Add, after the existing 4.5.5, the following new subclause:
4.6 Contents and structure of valve loss determination report
The manufacturer or bidder shall prepare and submit to the purchaser a detailed report
explaining how the losses in the VSC valves have been determined and including a
breakdown of the valve losses into the constituent parts P to P for each operating
V1 V9
condition at which losses are required to be guaranteed.
At the bid stage, and (where requested in the contract) after contract award but before the
manufacturing of valve components, the report shall document the assumptions used in
arriving at the calculated value of losses. After manufacturing, the report shall document the
actual values of test data derived from characterisation tests and routine tests on components.
Although a breakdown of the valve losses into the constituent parts P to P is requested,
V1 V9
only the total valve losses P shall be subject to financial evaluation.
Vt
A recommended list of data to be included in the report is presented in Annex B.
5.1 General
Add, after the existing Figure 2, the following new paragraphs:
To simplify the process of mathematically analysing conduction losses, the on-state voltage of
IGBTs and diodes is usually represented as a piecewise-linear approximation with a threshold
voltage V and a slope resistance R , as shown in Figure 2 of IEC 62751-1:2014.
0 0
It is possible to obtain greater accuracy by using a more exact model of the device on-state
voltage (for example, using a polynomial function to represent the on-state voltage) rather
than the piecewise-linear approximation, and then performing a direct numerical integration.
However, the piecewise-linear approximation is preferred because it simplifies the calculation
process, allows greater transparency and still permits good accuracy to be obtained, provided
the measurements used to derive the piecewise-linear approximation are made at appropriate
values of current. Therefore, it is recommended that V and R are determined by measuring
0 0
on-state voltage at 100 % and 33 % of the device rated current and performing a linear
extrapolation.
In the event that the purchaser prefers to use the more accurate method using a polynomial
function, then this shall be clearly stated in the purchasing specification, and all bidders are
expected to calculate power losses in a comparable way.
5.2 IGBT conduction loss
Replace the existing second paragraph, starting with "By means of…" and including
Equations (2) to (5) and their key, as well as the existing third paragraph, by the following new
text:
By means of numerical simulation, the currents shall be calculated for the IGBTs T1 and T2
for each MMC building block, respectively:
t
i
I =⋅⋅i ()t dt (2)
T1av T1
∫
t
i 0
t
i
I =⋅⋅i ()t dt (3)
T2av T2
∫
t
i 0
IEC 62751-2:2014/AMD1:2019 – 5 –
© IEC 2019
t
i
I =⋅⋅i ()t dt (4)
T1rms T1
∫
t
i
t
i
I =⋅⋅i ()t dt (5)
T2rms T2
∫
t
i 0
where
t is the integration time used in the simulation;
i
t shall not be less than 1 s.
i
If different IGBT types are used for T1 and T
...