Post on 28-May-2018
Brisbane Australia, 19-21 October 2011
© Siemens AG 2011
Energy Sector
Prospects of the new SVC with modular Multilevel Voltage Source Converter
Marcos Pereira Martin Pieschel Ralf Stoeber
SB4 Colloquium 2011
CIGRE – Brisbane / M. PereiraPage 1 © Siemens AG 2011 Energy Sector
FACTS devices: line-commutated vs. self-commutated converters
Example:
Advanced STATCOM
SVC PLUSSVC PLUSSVC “Classic”SVC “Classic” SVC PLUSSVC “Classic” SVC PLUSSVC PLUSSVC “Classic”SVC “Classic” SVC PLUSSVC “Classic”
- Compactness
- Short Response Time
- Controllability
CIGRE – Brisbane / M. PereiraPage 2 © Siemens AG 2011 Energy Sector
FACTS devices: line-commutated vs. self-commutated converters
SVC PLUSSVC PLUSSVC PLUSSVC PLUSSVC PLUSSVC PLUS
UNET UVSC
ILc
QNET= UNET . (- j. ILc)
UNET= UVSC + ULc
QNET= UNET . UVSC - UNET
ω . Lc
UNET
UVSC
ULc
ILc
Example:
Advanced STATCOM
- Compactness
- Short Response time
- Controllability
CIGRE – Brisbane / M. PereiraPage 3 © Siemens AG 2011 Energy Sector
Transmission level voltage applications:two-level and multilevel converters
L1L2L3
P
N
Neutral pointdiode-clampedthree-level converter
Two level converterwith series connectedswitches
↓Filters required forwave form construction andharmonics elimination.
↓High switching frequency
↓Sharp voltage steps
↓Measures required foruniform voltage sharing(snubbers)
↓Special gate drivesrequired to compensateswitching time tolerances
CIGRE – Brisbane / M. PereiraPage 4 © Siemens AG 2011 Energy Sector
The SVC PLUS usesModular Multilevel Converter (MMC)
MMC with cascaded H-bridges and isolated capacitors
Very clean voltage wave formand limited voltage steps
vvvv
...with modest switching frequency
CIGRE – Brisbane / M. PereiraPage 5 © Siemens AG 2011 Energy Sector
The SVC PLUS usesModular Multilevel Converter (MMC)
MMC with cascaded H-bridges and isolated capacitors
+ switches optimized forlow conduction losses
= reduction in total losses ✓
✓ High controllability, fast response
✓ Modularity, equal loading of modules
Very clean voltage wave form
...with modest switching frequency
CIGRE – Brisbane / M. PereiraPage 6 © Siemens AG 2011 Energy Sector
Modular Multilevel Converter (MMC) High performance
Step in the output order
CIGRE – Brisbane / M. PereiraPage 7 © Siemens AG 2011 Energy Sector
Modular Multilevel Converter (MMC) High performance
HV-side single-phase short-circuit
CIGRE – Brisbane / M. PereiraPage 8 © Siemens AG 2011 Energy Sector
SVC PLUS as containerized solution.Picture: Kikiwa, New Zeeland, 2 x “M” (±35 Mvar)
2 years later: 34 units under project execution / commercial operation
First two units: Thanet, UK, end 2009
CIGRE – Brisbane / M. PereiraPage 9 © Siemens AG 2011 Energy Sector
SVC PLUS as containerized solution:equipment layout
CIGRE – Brisbane / M. PereiraPage 10 © Siemens AG 2011 Energy Sector
SVC PLUS allows improved(combined) features and FACTS applications
Flicker control(e.g. arc furnaces)
Voltage control,power system stability
CIGRE – Brisbane / M. PereiraPage 11 © Siemens AG 2011 Energy Sector
MMC allows new or improved(combined) features and FACTS applications
Flicker control(e.g. arc furnaces)
Voltage control,power system stability
CIGRE – Brisbane / M. PereiraPage 12 © Siemens AG 2011 Energy Sector
MMC allows new or improved(combined) features and FACTS applications
Flicker control(e.g. arc furnaces)
Grid access(e.g. wind farms)
Phase balance(e.g. railways)
Voltage control,power system stability
CIGRE – Brisbane / M. PereiraPage 13 © Siemens AG 2011 Energy Sector
Converter module: H-bridge with capacitor and protective bypassing device
MMC Topology: Device capacitance distributed among the modules
Very small inductance in thecommutation path
= fast commutation time,no snubbers needed
= reduction in total losses ✓
Smaller capacitors = limited dischargeenergy in case of short-circuit in thecapacitor or in the module ✓
Redundancy of defective module throughbypass covers electronics and capacitor
CIGRE – Brisbane / M. PereiraPage 14 © Siemens AG 2011 Energy Sector
Alternatives and expectations – Example:DC/AC MMC converter in FACTS applications
Vision: MMC UPFC
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Shunt reactivepower compensation
Load balancing
AC system
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Shunt reactivepower compensation
Energystorage
AC system
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Shunt reactivepower compensation
Power flowcontrol
AC system
CIGRE – Brisbane / M. PereiraPage 15 © Siemens AG 2011 Energy Sector
Conclusions:
SVC PLUS is a MMC STATCOM. It was initially conceived for Grid Access, specially in connection with large off-shore wind parks.
Extended application range for network voltage and stability support, HVDC reactive power dynamic control and power quality (flicker mitigation).
Compact design, low losses, fast response and competitive costsdue to MMC technology. Containerized standard solutionsfrom ±25 Mvar up to ±200 Mvar with 4 x 50 Mvar parallel units and open-rack units.
First 2 units commissioned in 2009.Meanwhile, 34 units under project execution / commercial operation.
New developments for FACTS using MMC technology are expected to come on in the next time.