Modular Multilevel Converters (MMC) are becoming increasingly popular with the development of HVDC connection and, in the future, Multi Terminal DC grid. A lot of publications have been published about this topology these last years since it was first proposed. Many of them deal with converter control methods, other address the method of estimating losses. Usually, the proposed losses estimation techniques are associated to simple control methods For VSC (Voltage Sources Converters) topology, the losses minimization is based on the limitation of the RMS currents values. This hypothesis is usually extended to the control of MMC, by limiting the differential currents to their DC component, without really being checked. This paper investigates the impact of two control algorithms variants on electrical quantities (currents, capacitor voltages ripple, losses). From the published results, it is shown that in some cases the usual choice is not the best one

BELHAOUANE, Mohamed Moez

COLAS, Frédéric

DELARUE, Philippe

FREYTES, Julian

GRUSON, François

GUILLAUD, Xavier

SAMIMI, Shabab

SAM : Science Arts et Métiers

Science Arts & Métiers (SAM)is an open access repository that collects the work of Arts et Métiers Institute ofTechnology researchers and makes it freely available over the web where possible.This is an author-deposited version published in: https://sam.ensam.euHandle ID: .http://hdl.handle.net/10985/13677To cite this version :François GRUSON, Julian FREYTES, Shabab SAMIMI, Philippe DELARUE, Xavier GUILLAUD,Frédéric COLAS, Mohamed Moez BELHAOUANE - Impact of control algorithm solutions onModular Multilevel Converters electrical waveforms and losses - In: EPE ECCE europe 2014,Suisse, 2015-09-07 - EPE ECCE europe 2015 - 2015Any correspondence concerning this service should be sent to the repositoryAdministrator : archiveouverte@ensam.eu• Context : control of the stored energy of the MMC (Modular Multilevel Converter)  • Objectives :  Study the impact of two control variants (compensation of the average or the instantaneous AC grid power) :  differential and AC grid currents, capacitor voltages ripple, losses.  F. Gruson1, J. Freytes2, S. Samimi2, P. Delarue3, X. Guillaud2, F. Colas1, M.M. Belhaouane2  1L2EP, Arts et Métiers ParisTech, 8Bd Louis XIV, 59046 Lille, France; 2L2EP, Ecole Centrale de Lille, 59650 Villeneuve d’Ascq, France ;  3 L2EP, Université Lille 1, 59655 Villeneuve d’Ascq, France • The impact of two control variants (compensation of the average or the instantaneous AC grid power) : differential and AC grid currents, capacitor voltages ripple, losses.   Conclusion Simulation Results Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses   If capacitor voltage balancing is achieved: Simplified  model of MMC  uam ubm ucmlamlbmlcmgavgbvgcvgaigbigciuai ubi ucilbilbilci_cua totv _cub totv _cuc totv_cla totv _clb totv _clc totvdcidcvCNCNCNCNCNCNmuavmlavmubvmlbvmucvmlcvCurrent Control of the MMC Converter Modeling of the MMC converter  _ __ _;;ml i l i cl i tot mui l i clui totcl i tot clui totl i l i u i u iv m v v m vdv dvC Cm i m iN dt N dt  ; ;2 2 2mu i ml i ml i mu iui lidiff i diff i v iv v v vi ii v v   ( ) ( ) ( )2 2 2gdarm arm armvd gd gd gqdiL R Lv v L R i L idt      ( ) ( ) ( )2 2 2gqarm arm armvq gq v q gddiL R Lv v L R i L idt      +- _refdiff ii i diffC s i puC ssgd refigqrefigqigdi 1 sP s  R sP ++giv'pu puL _cui totv_cli totvdiff iilimgii/ 2dcv'pu puL  i puC s++uim , ,with i a b c , ,with i a b cThis converter has 11 independent state variables  Requires 11 control loops to achieve the global control  Current control  5 control loops    Stored Energy Control  6 other control loops (3*sum+3*difference)  Stored Energy Control of the MMC Converter  _( )., ,( )ˆˆcl i cu idc diff i DC AC iTcl i cu ivi diff i ACTd W WV i pdtwith i a b cd W Wv idt        0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90246810x 108time (s)Active Power (W)  0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9024681012x 107time (s)Réactive Power (VAR)  QmesQrefPacPdcPref 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.966.57x 105Time (s)Equivalent CapacitorVoltages (V)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9-200002000Time (s)AC Grid       Currents (A)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9-50005001000Time (s)differential   Currents (A)   Δ = 104kV Δ = 100kVAt t=0.1s : a slope is done in the AC power references (Pac) equal to 0.8 GW and the reactive reference (Qac) to 100MVAR.   Before 0.55s, the Stored Energy control compensate the average power (Pac/3)  After 0.55s, the Stored Energy control compensate the instantaneous one for each phase (paci). L 50 mH   C 10 mF R 50 mΩ   N 400 Larm 50 mH Vdc 640 kV Rarm 50 mΩ   ω 314 rad.s-1 SN 1100MVA   Vg 192 kV Tr_igdq 5ms   Tr ∑Vci_tot 50ms Tr_idiffi 10ms   Tr ΔVci_tot 100ms Conduction losses: Simulation Losses Comparison Results Switching losses: Passive elements losses: + + = Total MMC losses: ++  vDCC sdcv ACipdiff i DC refi  vACC sdcvdiff i AC refp diff i AC refi diff i DC refp -+2_cli totvFilter-+ 2_cui totvFilter2_ _refcli totv2_ _refcui totv+++-+++- , ,3ACACiPp with i a b c   introducing the AC fluctuating power term     -Reduce the ripples in the vc_tot since pAC= pDC    The choice of introducing or not the fluctuating part of the AC power modifies the control   - different quantity of activated sub-modules   - current passes through a different number of IGBT and diodes.   it may have sense to use a control inducing a slightly larger current if this current passes through more diodes.   - IGBT conduction losses>diode conduction losses  the hypothesis of limiting the RMS current can be questionable.    521 ARMS 581 ARMS • compensation of the average AC grid power: • differential currents are constant • Vci_tot ripple are 4% higher • compensation of the instantaneous AC grid power: • differential currents have DC and AC components at 2ω • RMS differential currents is 11% higher   • Losses  Usual assumption is not every time validate the MMC converter using considerable number of semiconductor; the losses are not only related to the RMS current value but also to the way of this current (diode or IGBT)  therefore to the control Usual assumption:  To Limit the losses, the Idiff-i value is limited by considering only the average power of the AC grid (Pac) in the stored energy control (pAC≠ pDC)  cos(2 t ) , ,3ACACi gi giPp V I with i a b c    cos(2 t )3ACACi gi giPp V I    3ACACiPp 

Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses

Modular Multilevel Converters (MMC) are becoming increasingly popular with the development of HVDC connection and, in the future, Multi Terminal DC grid. A lot of publications have been published about this topology these last years since it was first proposed. Many of them deal with converter control methods, other address the method of estimating losses. Usually, the proposed losses estimation techniques are associated to simple control methods For VSC (Voltage Sources Converters) topology, the losses minimization is based on the limitation of the RMS currents values. This hypothesis is usually extended to the control of MMC, by limiting the differential currents to their DC component, without really being checked.This paper investigates the impact of two control algorithms variants on electrical quantities (currents, capacitor voltages ripple, losses). From the published results, it is shown that in some cases the usual choice is not the best one

Gruson, François

Freytes, Julian

Samimi, Shabab

Delarue, Philippe

Guillaud, Xavier

Colas, Frederic

Belhaouane, Moez

Hal-Diderot

SAM;  the Arts et Métiers ParisTech open access repository

Science Arts & Métiers (SAM)
is an open access repository that collects the work of Arts et Métiers ParisTech
researchers and makes it freely available over the web where possible.
This is an author-deposited version published in: https://sam.ensam.eu
Handle ID: .http://hdl.handle.net/10985/13677
To cite this version :
François GRUSON, Julian FREYTES, Shabab SAMIMI, Philippe DELARUE, Xavier GUILLAUD,
Frédéric COLAS, Mohamed Moez BELHAOUANE - Impact of control algorithm solutions on
Modular Multilevel Converters electrical waveforms and losses - In: EPE ECCE europe 2014,
Suisse, 2015-09-07 - EPE ECCE europe 2015 - 2015
Any correspondence concerning this service should be sent to the repository
Administrator : archiveouverte@ensam.eu
• Context : control of the stored energy of the MMC (Modular Multilevel Converter)  
• Objectives :  
Study the impact of two control variants (compensation of the average or the instantaneous AC grid power) :  
differential and AC grid currents, capacitor voltages ripple, losses.  
F. Gruson1, J. Freytes2, S. Samimi2, P. Delarue3, X. Guillaud2, F. Colas1, M.M. Belhaouane2  
1L2EP, Arts et Métiers ParisTech, 8Bd Louis XIV, 59046 Lille, France; 2L2EP, Ecole Centrale de Lille, 59650 Villeneuve d’Ascq, France ;  
3 L2EP, Université Lille 1, 59655 Villeneuve d’Ascq, France 
• The impact of two control variants (compensation of the average or the instantaneous AC grid power) : differential and AC grid currents, capacitor voltages ripple, losses.  
 
Conclusion 
Simulation Results 
Impact of control algorithm solutions on Modular Multilevel 
Converters electrical waveforms and losses  
 If capacitor voltage balancing is achieved: 
Simplified  model of MMC  
uam ubm ucm
la
m
lb
m
lc
m
gav
gb
v
gcv
gai
gb
i
gci
uai ubi uci
lb
i
lb
i
lc
i
_cua totv _cub totv _cuc totv
_cla totv _clb totv _clc totv
dci
dcv
C
N
C
N
C
N
C
N
C
N
C
N
muav
mlav
mubv
mlbv
mucv
mlcv
Current Control of the MMC Converter Modeling of the MMC converter  
_ _
_ _
;
;
ml i l i cl i tot mui l i clui tot
cl i tot clui tot
l i l i u i u i
v m v v m v
dv dvC C
m i m i
N dt N dt
 


 

; ;
2 2 2
mu i ml i ml i mu iui li
diff i diff i v i
v v v vi i
i v v
 
  
( ) ( ) ( )
2 2 2
gdarm arm arm
vd gd gd gq
diL R L
v v L R i L i
dt
      
( ) ( ) ( )
2 2 2
gqarm arm arm
vq gq v q gd
diL R L
v v L R i L i
dt


      
+- _refdiff ii
 i diffC s




 i puC s
s
gd ref
i
gqref
i


gqi
gd
i


 1 sP 
s  R sP 
+
+
giv


'
pu puL 
_cui totv
_cli tot
v
diff i
i
lim
gii
/ 2dcv
'
pu puL 
 i puC s




+
+
uim
 , ,with i a b c
 , ,with i a b c
This converter has 11 independent state variables  
Requires 11 control loops to achieve the global control  
Current control  5 control loops  

 
 
Stored Energy Control  6 other control loops (3*sum+3*difference)  
Stored Energy Control of the MMC Converter 
 
_
( )
.
, ,
( )
ˆˆ
cl i cu i
dc diff i DC AC i
T
cl i cu i
vi diff i AC
T
d W W
V i p
dt
with i a b c
d W W
v i
dt


  
  
 

 
 
 
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
2
4
6
8
10
x 10
8
time (s)
A
c
ti
v
e
 P
o
w
e
r 
(W
)
 
 
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
2
4
6
8
10
12
x 10
7
time (s)
R
é
a
c
ti
v
e
 P
o
w
e
r 
(V
A
R
)
 
 
Qmes
Qref
Pac
Pdc
Pref 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
6
6.5
7
x 10
5
Time (s)
E
q
u
iv
al
en
t 
C
ap
ac
it
o
r
V
o
lt
ag
es
 (
V
)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
-2000
0
2000
Time (s)
A
C
 G
ri
d
  
  
  
 C
u
rr
en
ts
 (
A
)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
-500
0
500
1000
Time (s)
d
if
fe
re
n
ti
al
  
 C
u
rr
en
ts
 (
A
) 
 
 
Δ = 104kV Δ = 100kV
At t=0.1s : a slope is done in the AC power references (Pac) equal to 0.8 GW and the reactive reference (Qac) to 100MVAR.  
 Before 0.55s, the Stored Energy control compensate the average power (Pac/3) 
 After 0.55s, the Stored Energy control compensate the instantaneous one for each phase (paci). 
L 50 mH   C 10 mF 
R 50 mΩ   N 400 
Larm 50 mH Vdc 640 kV 
Rarm 50 mΩ   ω 314 rad.s
-1 
SN 1100MVA   Vg 192 kV 
Tr_igdq 5ms   Tr ∑Vci_tot 50ms 
Tr_idiffi 10ms   Tr ΔVci_tot 100ms 
Conduction losses: 
Simulation Losses Comparison Results 
Switching losses: Passive elements losses: + + 
= 
Total MMC losses: 
+
+  vDCC s
dcv ACip
diff i DC refi 
 vACC s
dcv
diff i AC refp diff i AC refi 
diff i DC refp 
-
+
2
_cli totvFilter
-
+ 2
_cui totvFilter
2
_ _refcli totv
2
_ _refcui totv
+
+
+
-
+
+
+
-
 , ,
3
AC
ACi
P
p with i a b c 
 
 introducing the AC fluctuating power term 
 
 
 
 -Reduce the ripples in the vc_tot since pAC= pDC 
 
  
The choice of introducing or not the fluctuating part of the AC power modifies the control  
 - different quantity of activated sub-modules  
 - current passes through a different number of IGBT and diodes.  
 
it may have sense to use a control inducing a slightly larger current if this current passes through 
more diodes.  
 - IGBT conduction losses>diode conduction losses 
 
the hypothesis of limiting the RMS current can be questionable.  
 
 
521 ARMS 581 ARMS 
• compensation of the average AC grid power: 
• differential currents are constant 
• Vci_tot ripple are 4% higher 
• compensation of the instantaneous AC grid power: 
• differential currents have DC and AC components at 2ω 
• RMS differential currents is 11% higher 
 
 
• Losses  
Usual assumption is not every time validate 
the MMC converter using considerable number of semiconductor; the losses are not only related to the RMS current value but also to the way of this current (diode or IGBT)  therefore to the control 
Usual assumption:  
To Limit the losses, the Idiff-i value is limited by considering only the average power of the AC grid (Pac) 
in the stored energy control (pAC≠ pDC) 
 cos(2 t ) , ,
3
AC
ACi gi gi
P
p V I with i a b c    
cos(2 t )
3
AC
ACi gi gi
P
p V I    
3
AC
ACi
P
p 


English

HAL Descartes

https://sam.ensam.eu/bitstream/10985/13677/1/Impact%20of%20control%20algorithm%20solutions%20on%20Modular%20Multilevel%20Converters%20electrical%20waveforms%20and%20losses.pdf

Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses

Abstract

Similar works

Full text

Available Versions

SAM : Science Arts et Métiers

Hal-Diderot

SAM; the Arts et Métiers ParisTech open access repository

HAL Descartes