IEC 62751-2:2014/AMD1:2019
(Amendment)Amendment 1 - Power losses in voltage sourced converter (VSC) valves for high-voltage direct current (HVDC) systems - Part 2: Modular multilevel converters
Amendment 1 - Power losses in voltage sourced converter (VSC) valves for high-voltage direct current (HVDC) systems - Part 2: Modular multilevel converters
Amendement 1 - 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
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Standards Content (Sample)
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
IEC 62751-2:2014-08/AMD1:2019-08(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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
Warning! Make sure that you obtained this publication from an authorized distributor.
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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 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.
---------------------- Page: 4 ----------------------
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)".
---------------------- Page: 5 ----------------------
– 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
1
I =⋅⋅i ()t dt (2)
T1av T1
∫
t
i 0
t
i
1
I =⋅⋅i ()t dt (3)
T2av T2
∫
t
i 0
---------------------- Page: 6 ----------------------
IEC 62751-2:2014/AMD1:2019 – 5 –
© IEC 2019
t
i
1
2
I =⋅⋅i ()t dt (4)
T1rms T1
∫
t
i
0
t
i
1
2
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 T2, corresponding values for threshold voltages
and slope resistances shall be used accordingly.
5.3 Diode conduction losses
Replace the existing second paragraph, starting with "By means of…", including Equations (7)
to (10), the key to these equations and the note, by the following new text:
By means of numerical simulation, the currents shall be calculated for the diodes D1 and D2
for each MMC building block, respectively:
t
i
1
I =⋅⋅i t dt (7)
()
D1av D1
∫
t
i 0
t
i
1
I =⋅⋅i t dt (8)
()
D2av D2
∫
t
i 0
t
i
1 2
I =⋅⋅i t dt (9)
()
D1rms D1
∫
t
i 0
t
i
1 2
I =⋅⋅i t dt (10)
()
D2rms D2
∫
t
i 0
where
t is the integration time used in the simulation;
i
shall not be less than 1 s.
t
i
If different diode types are used for D1 and D2, corresponding values for threshold voltages
and slope resistances shall be used accordingly.
5.4 Other conduction losses
Replace the second sentence of the first existing paragraph by the following new sentences:
---------------------- Page: 7 ----------------------
– 6 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
For modular multi-level converters, this mainly consists of interconnecting busbars. Losses in
valve reactors shall be considered separately from valve losses and calculated using the
principles defined for AC filter reactors in IEC 61803.
9.1 Snubber circuit losses
Replace the existing note by the following new paragraph:
Including a snubber parallel to a VSC valve level influences the turn-on/turn-off behaviour of
the IGBT/diode, which means that the snubber circuits shall be correctly represented during
the characterisation tests on the semiconductor devices.
9.2.1 General
Replace the first existing sentence of the fourth paragraph by the following new sentences:
The power consumption of each valve electronics unit should be determined by direct
measurement on a sample of real valve electronics units under representative switching
conditions (voltage, current, switching frequency etc). Tests shall be performed on a minimum
quantity of valve electronics units equivalent to five submodules or 10 VSC valve levels (for
the CTL design).
Annex A – Description of power loss mechanisms in MMC valves
Figure A.2 – Phase unit of the cascaded two-level converter (CTL) in half-bridge form
Replace "VSC valve leve" by "VSC valve level".
Figure A.3 – Basic operation of the MMC converters
Replace the three occurrences of "I " by "I ", where I is an AC phase current on the
L C C
converter side of the transformer.
Figure A.4 – MMC converters showing composition of valve current
Replace the four occurrences of "I " by "I ".
L C
rd
Figure A.6 – Effect of 3 harmonic injection on converter voltage and current
Replace the two occurrences of "I " by "I ".
L C
Figure A.9 – Typical patterns of conduction for inverter operation (left) and rectifier
operation (right)
Replace the existing title of Figure A.9 by the following new title:
Figure A.9 – Typical patterns of conduction for inverter operation (left) and rectifier
operation (right), based on the submodule configuration of Figure A.7 a)
Figure A.10 – Example of converter with only one MMC building block per valve to
illustrate switching behaviour
Replace "I " by "I ".
L C
A.3.2.1 Approximate analytical solution
Equation (A.3)
Replace "i " by "i ".
v vtt
---------------------- Page: 8 ----------------------
IEC 62751-2:2014/AMD1:2019 – 7 –
© IEC 2019
Add, immediately after the existing Equation (A.3), the following new text:
where
i (ωt) is the instantaneous current between the terminals of the valve.
vtt
Equation (A.4)
Replace "i " by "i ".
v vtt
Figure A.13 – Valve current and mean rectified valve current
Replace the existing Figure A.13 by the following new figure:
Figure A.13 – Valve current and mean rectified valve current
Equations (A.5)
" by "I ".
Replace "I
L C
Equations (A.6)
" by "I ".
Replace "I
L C
Equations (A.7)
Replace "I " by "I ".
L C
Equations (A.8)
Replace "I " by "I ".
L C
A.3.2.2 Exact analytical solution
Replace, in the existing title of this subclause, the word "Exact" by "Improved".
---------------------- Page: 9 ----------------------
– 8 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
Equation (A.11)
Replace "u " by "u ".
v vtt
Replace, in the key to Equation (A.11), the existing symbol "u (ωt)", including its definition, by
v
the following new symbol and definition:
u (ωt) is the valve terminal-to-terminal voltage as a function of time;
vtt
Equation (A.12)
Replace "i " by "i ".
v vtt
Equation (A.13)
Replace "i " by "i "
v vtt
Equation (A.14)
Replace "i " by "i "
v vtt
Equation (A.15)
Replace "i " by "i ".
v vtt
Add, after the last paragraph of A.3.2.2, the following new paragraphs and new equation:
A further improvement to the analytical calculation of semiconductor conduction losses can be
made by using a more sophisticated approximation for the device on-state voltage instead of
the piecewise-linear model using V and R For example:
.
0 0
V ,V= A+BI⋅+⋅C ln(I++1) D⋅ I (A.1)
ce()sat f
However, this improved model comes at the price of increased simulation complexity and
reduced transparency and should only be used when specifically agreed by the purchaser.
A.3.3 MMC building block d.c. capacitor losses
Add a colon to the end of the first paragraph.
A.4.2 Analysis of state changes during cycle
Replace, in the first sentence of the second paragraph, the words "is very complex" by "can,
depending on the modulation strategy chosen, be complex".
A.5.2.2 DC voltage-dependent losses with MMC building block – Analytical method
Replace, in the existing title of the subclause, the words "with MMC building block" by "in
MMC building block".
Replace, in items a) and b) of the last paragraph, the words "total losses" by "total d.c.
voltage-dependent losses", and the words "single MMC building block loss" by "single MMC
building block d.c. voltage-dependant loss".
A.5.2.3 DC voltage-dependent losses with valve – Analytical method
Replace, in the existing title, the words "with valve" by "across complete valve".
---------------------- Page: 10 ----------------------
IEC 62751-2:2014/AMD1:2019 – 9 –
© IEC 2019
A.5.3.2.2 Type A
Replace the two occurrences of "power circuit" by "power supply circuit".
A.5.3.2.3 Type B
Replace the three occurrences of "power circuit" by "power supply circuit".
A.6.2 Two-level full-bridge MMC building block
Add, in the first sentence of the penultimate paragraph, the word "(over-modulation)" after
"d.c. pole-to-pole voltage".
Replace, in the penultimate paragraph, the last existing sentence by the following new
sentence:
When such over-modulation is used, overall conduction losses of the full-bridge converter are
therefore somewhat less than twice those of a half-bridge converter.
A.6.3 Multi-level MMC building blocks
Delete, in the first sentence of the first existing paragraph, the words "and used in the
traditional "two-level" converter,".
Add, after the existing Annex A, the following new annex:
---------------------- Page: 11 ----------------------
– 10 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
Annex B
(informative)
Recommended data to be supplied with the loss calculation report
The data showed in Tables B.1 and B.2 is recommended to be included in the loss calculation
report in order to facilitate comparisons between reports from different bidders. The format of
data is based on the assumption of a half-bridge MMC; in the event that a different topology is
used, the content should be adapted accordingly. Data should be provided for each operating
point at which losses are subject to financial evaluation.
Table B.1 – Valve loss data
Losses categories Loss Parameters Value
power
kW
1) IGBT conduction losses 2) 3) IGBT threshold voltage (V ) 4)
0T
a
(P )
V1
5) IGBT slope resistance (R ) 6)
0T
7) mean current of IGBT T1 (I ) 8)
T1av
9) rms current of IGBT T1 (I ) 10)
T1rms
11) mean current of IGBT T2 (I ) 12)
T2av
13) rms current of IGBT T2 (I ) 14)
T2rms
15) diode conduction losses 16) 17) diode threshold voltage (V ) 18)
0D
a
(P )
V2
19) diode slope resistance (R ) 20)
0D
21) mean current of diode D1 (I ) 22)
D1av
23) rms current of diode D1 (I ) 24)
D1rms
25) mean current of diode D2 (I ) 26)
D2av
27) rms current of diode D2 (I ) 28)
D2rms
29) other valve conduction 30) 31) rms current flowing in each series 32)
losses (P ) resistive element (I )
V3 rms_k
33) total resistance of each series 34)
resistive elements (R )
s_k
35) d.c. voltage-dependent 36) 37) rms value (including d.c. 38)
losses (P ) component) of the voltage across
V4
each parallel resistive component
(U )
rms
39) resistance of each parallel resistive 40)
component (R )
dc
41) d.c. capacitor losses (P ) 42) 43) rms current flowing in the d.c. 44)
V5
capacitor (I )
crms
45) average equivalent series 46)
resistance of the d.c. capacitor
(R )
ESR
47) IGBT switching losses (P ) 48) 49) average turn-on energy of T1 52)
V6
(E )
on,T1
53)
50) at current=
54)
51) and temperature=
55) average turn-on energy of T2 58)
(E )
on,T2
59)
56) at current=
60)
57) and temperature=
61) average turn-off energy of T1 64)
(E )
off,T1
65)
---------------------- Page: 12 ----------------------
IEC 62751-2:2014/AMD1:2019 – 11 –
© IEC 2019
Losses categories Loss Parameters Value
power
kW
62) at current= 66)
63) and temperature=
67) average turn-off energy of T2 70)
(E )
off,T2
71)
68) at current=
72)
69) and temperature=
73) diode turn-off losses (P ) 74) 75) average diode recovery energy of 78)
V7
D1 (E )
rec,D1
79)
76) at current=
80)
77) and temperature=
81) average diode recovery energy of 84)
D2 (E )
rec,D2
85)
82) at current=
86)
83) and temperature=
87) snubber losses (P ) (if 88) 89) average energy dissipated in the 91)
V8
any) snubber resistor for turn-on (E )
sn,on
90) at current=
92)
93) average energy dissipated in the 95)
snubber resistor for turn-off (E )
sn,off
94) at current=
96)
97) valve electronics power 98) 99) 100)
consumption (P )
V9
101) total valve losses (P ) 102) 103) 104)
Vt
a
If the on-state voltage of IGBTs and diodes is represented by polynomial functions of other more accurate
representations, the threshold voltage and slope resistance data and I and I data are not required.
av rms
However, the bidder should provide full details of the polynomial function used, including its coefficients.
Table B.2 – Other data
Devices Junction temperature
°C
1) T1 2)
3) T2 4)
5) D1 6)
7) D2 8)
Bibliography
Delete reference to IEC 61803.
Add the following new reference:
CIGRÉ WG B4-75, Feasibility study for assessment of lab losses measurement of VSC valves
___________
---------------------- Page: 13 ----------------------
– 12 – IEC 62751-2:2014/AMD1:2019
© IEC 2019
AVANT-PROPOS
Le présent amendement a été établi par le sous-comité 22F: Électronique de puissance pour
les réseaux électriques de transport et de distribution, du comité d'études 22 de l'IEC:
Systèmes et équipements électroniques de puissance.
Le texte de cet amendement est issu des documents suivants:
CDV Rapport de vote
22F/479/CDV 22F/488B/RVC
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant
abouti à l'approbation de cet amendement.
Le comité a décidé que le contenu de cet amendement et de la publication de base ne sera
pas modifié avant la date de stabilité indiquée sur le site web de l'IEC sous
"http://webstore.iec.ch" dans les données relatives à la publication recherchée. A cette date,
la publication sera
• reconduite,
• supprimée,
• remplacée par une édition révisée, ou
• amendée.
IMPORTANT – Le logo "colour inside" qui se trouve sur la page de couverture de
cette publication indique qu'elle contient des couleurs qui sont considérées comme
utiles à une bonne compréhension de son contenu. Les utilisateurs devraient, par
conséquent, imprimer cette publication en utilisant une imprimante couleur.
_____________
2 Références normatives
Ajouter la nouvelle référence suivante:
IEC 61803, Détermination des pertes en puissance dans les postes de conversion en courant
continu à haute tension (CCHT)
3.1.11
état de fonctionnement à vide
Ajouter, après la définition existante, la nouvelle note suivante:
Note 1 à l'article: En principe, à l'état à vide, il convient qu'aucune commutation ne se produise, la valve étant
bloquée. Toutefois, dans certaines conceptions, il peut s'avérer nécessaire de réaliser des opérations
occasionnelles de commutation afin d'équilibrer les tensions entre les différentes parties du convertisseur. Dans le
cas présent, certaines pertes peuvent se produire et il est nécessaire de les prendre en considération.
---------------------- Page: 14 ----------------------
IEC 62751-2:2014/AMD1:2019 – 13 –
© IEC 2019
4 Conditions générales
4.1 Généralités
Remplacer, dans la troisième phrase de l'alinéa existant, le terme abrégé "CTLC" par "CTL".
4.2 Principe de détermination des pertes
Ajouter, à la fin du premier alinéa existant, la nouvelle phrase suivante:
Le fabricant doit justifier, dans le rapport de calcul des pertes, la façon dont les incertitudes
ont été prises en considération.
Remplacer les deux dernières phrases du troisième alinéa existant par les nouvelles phrases
suivantes:
Dans la pratique, ce mesurage exige d'utiliser un équipement de mesure conforme à l’état de
l’art, rivalisant avec les meilleurs équipements disponibles des instituts de métrologie
nationaux. À ce jour, bien que certains projets de partenariat industrie/université aient fait la
démonstration de prototypes d'équipements de mesure d'une exactitude satisfaisante,
l'expérience de l'industrie dans l'utilisation de tels équipements sur site reste faible. La
possibilité d'utiliser des mesures de laboratoire sur des valves à VSC pour permettre une
détermination plus précise des pertes de la valve est à l'étude au sein du CIGRÉ WG B4-75.
4.4 Méthode de calcul des pertes
Remplacer la première phrase du deuxième alinéa existant par la nouvelle phrase suivante:
La modélisation exacte du système à l'étude est une exigence importante pour ce type de
simulation.
4.5.2 Données d'entrée pour les simulations numériques
Remplacer le dernier élément de la liste existante par les nouveaux éléments suivants:
– Pour calculer les courants de la valve du convertisseur et les courants du condensateur
de bloc module MMC, qui sont la base du calcul des pertes correspondantes, l'utilisation
d'un modèle simplifié dans lequel les caractéristiques d'état et de commutation des IGBT
et des diodes sont représentées par les caractéristiques les plus défavorables applicables
à leur température de jonction maximale assignée est suffisante.
– Pour le calcul détaillé des pertes, la simulation doit également tenir compte des propriétés
des semi-conducteurs dépendant de la température de jonction (les tensions à l'état
passant, les pertes de commutation et de rétablissement, par exemple). Ces propriétés
reposent sur les essais de caractérisation tels que décrits dans l'IEC 62751-1:2014, 4.4.2.
Les températures de jonction en régime permanent des semi-conducteurs sont calculées
de manière itérative pour le point de fonctionnement correspondant afin de déduire les
pertes de semi-conducteur.
4.5.3 Données d'entrée provenant des simulations numériques
Ajouter, au dernier alinéa existant, la nouvelle phrase suivante:
Les courants moyen et efficace des IGBT et des diodes ne sont pas exigés si les pertes de
conduction d
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