Multilevel STATCOMs – a new converter topology that
opens up the market
Simon Sinsel, Siemens AG, Germany
Ian Ramsay, Siemens Inc., NC, USA
Key Messages
•
•
•
Source: Siemens AG
We describe three multilevel STATCOM
installations in Chile, Australia and the US.
Each multilevel STATCOM fulfills a different
primary electrical performance
requirement – dynamic voltage support,
load balancing and flicker reduction.
Secondary features of the multilevel
STATCOM technology favor its application
on these projects – modularity, low
interaction with the network in terms of
harmonics and the low amount of primary
equipment.
Agenda
Multilevel STATCOM Topology Overview
Case 1: Reactive Power Support for Increased Transmission Capacity
Case 2: Dynamic Load Balancing for Railway Applications
Case 3: Flicker Reduction
Conclusion
Multilevel STATCOM Topology Overview
Terminal A
Terminal B
Modul #1
Modul #n
Modul #2
Modul #n-1
Modul #3
Modul #n-2
Modul #4
Modul #n-3
~
Source: Siemens AG
• Multilevel STATCOM is built by Power Modules connected in series. The required
output determines the number of modules.
• The sum of all power module output voltages form the terminal voltage.
• The reactive power output is controlled via the amplitude of the converter voltage.
Reactive Power Support for Increased Transmission Capacity
Diego de Almagro, Chile
Initial situation
• Trip on one of three Cardones –
Maitencillo circuits led to voltage
instability in northern transmission
region.
• Dynamic voltage recovery criteria
could only be fulfilled by limiting
load on Cardones – Maitencillo lines
to 340 MW.
• Increased power demand and
relatively high generation cost in
northern region provided incentive
to increase transmission capacity on
the corridor.
Taltal
Diego de Almagro
Carrera
Pinto
SVC PLUS
Cardones
Maitencillo
Grid schematic with installed multilevel STATCOM; Source: TRANSELEC
Reactive Power Support for Increased Transmission Capacity
Diego de Almagro, Chile
Primary Project Requirement
• Increase of reactive power supply in
the northern region to
(1) comply with grid code and
(2) increase load limitation from
the southern grid region.
Additional Project Requirements
• Design, supply and commissioning
within 15 months.
• Increased level of redundancy
beneficial.
Taltal
Diego de Almagro
Carrera
Pinto
SVC PLUS
Cardones
Maitencillo
Grid schematic with installed multilevel STATCOM; Source: TRANSELEC
Reactive Power Support for Increased Transmission Capacity
Diego de Almagro, Chile
Vprim [pu]
220 kV
1.0
Results
• Compliance to required grid code criteria.
• Increased level of redundancy due to twin
configuration.
• Installation increased transmission
capacity through Cardones – Maitencillo
from 340 to 420 MW.
100 MVA
14 kV
0.5
-1.0
-0.5
capacitive
continuous operation
±50 Mvar
Multilevel STATCOM
0.5
1.0
Iprim [pu]
inductive
continuous operation
±50 Mvar
+40 Mvar
conventional SVC
SLD time
of installed
Siemensoperation
AG
limitedmultilevel
operationSTATCOM; Source:
time limited
Multilevel STATCOM
conventional SVC
Source: Siemens AG
Reactive Power Support for Increased Transmission Capacity
Diego de Almagro, Chile
Multilevel STATCOM installation at Diego de Almagro Substation; Source: Siemens AG
Dynamic Load Balancing for Railway Applications
Wycarbah, Duaringa & Bluff, Australia
Initial situation
• Projected substantial increase of
coal export via railway from
Central Queensland to coast for
export.
• Increased use of induction motor
locomotives instead of DC and
diesel-electric locomotives.
• Due to both drivers, potential
non-compliance to grid code
limitations for positive and
negative sequence voltage.
FS
SVC
FS
TrSC
SVC
Railway electrification scheme prior to upgrade
Source: Powerlink Queensland
Dynamic Load Balancing for Railway Applications
Wycarbah, Duaringa & Bluff, Australia
132 kV Feeder
Primary Project Requirement
• Installation of additional parallel
compensation devices at three
sites.
Additional Project Requirements
• Low interaction with the grid in
terms of harmonics.
• Electrical similarity between all
three sites beneficial.
100 MVA
132/30 kV
Tx1
Filter
Tx2
30/40 MVA
132/50 kV
Filter
Feeder
Auto
Transformers
±100 Mvar
Catenary
Schematic feeder station with installed multilevel STATCOM
Source: Powerlink Queensland
00:00:01
00:42:31
01:25:01
02:07:31
02:50:01
03:32:31
04:15:01
04:57:31
05:40:01
06:22:31
07:05:01
07:47:31
08:30:01
09:12:31
09:55:01
10:37:31
11:20:01
12:02:31
12:45:01
13:27:31
14:10:01
14:52:31
15:35:01
16:17:31
17:00:01
17:42:31
18:25:01
19:07:31
19:50:01
20:32:31
21:15:01
21:57:31
22:40:01
23:22:31
00:00:01
00:43:41
01:27:21
02:11:01
02:54:41
03:38:21
04:22:01
05:05:41
05:49:21
06:33:01
07:16:41
08:00:21
08:44:01
09:27:41
10:11:21
10:55:01
11:38:41
12:22:21
13:06:01
13:49:41
14:33:21
15:17:01
16:00:41
16:44:21
17:28:01
18:11:41
18:55:21
19:39:01
20:22:41
21:06:21
21:50:01
22:33:41
23:17:21
Dynamic Load Balancing for Railway Applications
Wycarbah, Duaringa & Bluff, Australia
160 A
140 A
120 A
100 A
80 A
60 A
Tx 1
40 A
Tx 2
20 A
00 A
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
NPS (in %)
STATCOM
in service
STATCOM out
of service
Comparison of NPS with multilevel STATCOM in service and out of service
Source: Powerlink Queensland
Results
• Significant reduction of NPS.
• Compliance to required grid
code criteria for negative and
positive phase sequence and
harmonics.
• Synergy potential in project
delivery, operation and
maintenance due to same
configuration.
Dynamic Load Balancing for Railway Applications
Wycarbah, Duaringa & Bluff, Australia
Multilevel STATCOM installation at Wycarbah Feeder Station; Source: Siemens AG
Flicker Reduction
CMC Steel, TX, USA
Initial situation
• CMC Steel Texas operates an 80
MVA AC Electric Arc Furnace on a
15 kV busbar.
• Existing STATCOM was not able to
reduce the flicker to required
value of Pst < 0.8 on the 138 kV
PCC.
• Grid code compliance only
possible with a flicker reduction
factor higher than four.
15 kV Electric Arc Furnace Busbar
STATCOM
±45 Mvar
Filter
STATCOM
±45 Mvar
Filter
SLD of multilevel STATCOM directly connected to Arc Furnace Busbar
Source: Siemens AG
Flicker Reduction
CMC Steel, TX, USA
Results
• Significant reduction
of Flicker.
• Flicker performance
of multilevel
STATCOM higher
compared to
conventional
Thyristor-based SVC
(Factor 4 vs. factor 2).
Flicker comparison of 1st generation STATCOM and multilevel STATCOM
Source: CMC Steel
Flicker Reduction
CMC Steel, TX, USA
Multilevel STATCOM installation at CMC Steel, Tx; Source: CMC Steel
Conclusion
•
•
•
Source: Siemens AG
We described three multilevel STATCOM
installations in Chile, Australia and the US.
Each multilevel STATCOM fulfills a different
primary electrical performance
requirement – dynamic voltage support,
load balancing and flicker reduction.
Secondary features of the multilevel
STATCOM technology favor its application
on these projects – modularity, low
interaction with the network in terms of
harmonics and the low amount of primary
equipment.
Thank You!
For questions, comments & discussions
please contact:
Simon Sinsel
simon.sinsel@siemens.com
Siemens AG, Germany
Ian Ramsay
ian.ramsay@siemens.com
Siemens Energy Inc., NC, USA
Source: Siemens AG
References
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•
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V. Hild, L. Kirschner, G. Pilz, L. Peuther and B. Gemmell, "The best of both –
Combining STATCOM with conventional thyristor based Static Var Compensator
technology", unpublished, presented at the EPRI Conference, Palo Alto, CA, 2013.
M. Pereira, D. Retzmann, J. Lottes, M. Wiesinger and G. Wong, “SVC PLUS: An
MMC STATCOM for Network and Grid Access Applications” presented at IEEE
PowerTech, Trondheim, 2011.
A. Handschick, A.J. Hernandes, F. Schettler, B. Strobl, “Voltage Control in Offshore
Wind Farms Using Switched Compensation Elements (MSCs, MSRs) Together with
the Reactive Power Capability of the Wind Turbine Generators” unpublished,
Erlangen, 2010.
A. Janke, R. Memisevic and G. Pilz, “Queensland Railways Upgrade Project”, SCB4
Colloquiu, CIGRE, Paris, 2011.