Prospects of Multilevel VSC Converter Technologies Giacomo Cordioli 1
11-2008
Dietmar Retzmann
E T PS SL/Re MT/Re
Energy Sector
Karl Uecker Power Transmission Division
General Features of VSC* Technology Grid Access for weak AC Networks Independent Control of Active and Reactive Power Supply of passive Networks and Black-Start Capability High dynamic Performance Low Space Requirements VSC Technology makes it feasible
HVDC PLUS offers additional Benefits * VSC: Voltage-Sourced Converter 2
Power Power Transmission Transmission Division Division
Benefits of HVDC PLUS ¾ Low Switching Frequency ¾ Reduction in Losses ¾ Less Stresses
In Comparison with 2 and 3-Level Converter Technologies … with Advanced VSC Technology
Siemens uses MMC Technology (Modular Multilevel Converter) E T PS SL/Re 4
4 11-2008
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Clean Energy to and from Platforms & Islands … 11-2008 E T PS MT/Re Power Transmission Division PTD
The Evolution of HVDC PLUS and VSC Technology Topologies: Two-Level
GTO / IGCT
Three-Level
IGBT in PP
Multilevel
IGBT Module
Power Electronic Devices: 5
11-2008
E T PS SL/Re MT/Re
Power Transmission Division
The Multilevel Approach
Vd /2
VConv.
Vd /2
Small Converter AC Voltage Steps Low Rate of Voltage Rise
6
11-2008
E T PS SL/Re MT/Re
Power Transmission Division
The Advanced Multilevel Approach: MMC – Modular Multilevel Converter
Vd VConv.
Low Generation of Harmonics Low Level of HF-Noise Low Switching Losses No Snubbers required 7
11-2008
E T PS SL/Re MT/Re
Power Transmission Division
HVDC PLUS with MMC – Basic Scheme Converter Arm Power Electronics PM 1
PM 1
PM 1
PM 2
PM 2
PM 2
PM n
PM n
PM n
Power Module (PM)
Vd ud
PM 1
PM 1
PM 1
D1
PM 2
PM 2
PM 2
D2
PM n
PM n
PM n
IGBT1
IGBT2
Phase Unit 8
11-2008
E T PS SL/Re MT/Re
Power Transmission Division
The Result: MMC – a perfect Voltage Generation
AC and DC Voltages controlled by Converter Arm Voltages: +Vd /2 VConv.
VAC
0
- Vd /2
9
11-2008
MT/Re E T PS SL/Re
Power Transmission Division
Dielectric Type Test of a Converter Arm Segment
The diagonal bracings are reinforcements for very high seismic stress levels … at High-Voltage Test Lab TU Dresden, Germany 10
11-2008
E T PS SL/Re MT/Re
Power Transmission Division
Results of Computer Simulation: 400 MW with 200 Power Modules per Converter Arm PLOTS : Graphs 250
+Ud
-Ud
US1
US2
US3
VDC + 200 kV
200 150 100
AC Converter Voltages
U [kV]
50 0 -50 -100 -150
VDC - 200 kV
-200 -250 2.00
is1
is2
is3
1.50 1.00
I [kA]
0.50
Currents at the AC Terminals
0.00 -0.50 -1.00 -1.50 -2.00 0.75
i1p
i2p
i3p
i1n
i2n
i3n
0.50 0.25
I [kA]
0.00 -0.25
Six Converter Arm Currents
-0.50 -0.75 -1.00
Obviously, no AC Filters required
-1.25 -1.50 1.000
11
1.010
11-2008
E T PS SL/Re MT/Re
1.020
Power Transmission Division
Dynamic Response to an AC Line-to-Ground Busbar Fault – Inv. Side (Computer Simulation) CONVERTER B UL1
UL2
UL3
100 75
AC Busbar Voltages
v_prim (kV)
50 25 0 -25 -50 -75 -100
250
VDC + 200 kV
US1
US2
US3
UdHP_B
UdHN_B
200 150
AC Converter Voltages
v_conv, v_dc (kV)
100 50 0 -50 -100 -150
VDC - 200 kV
-200 -250 1.20
DC Converter Current
IdHN_B
1.00
i_dc (kA)
Fault Ride-Through Capability
IdHP_B
0.80
0.60
0.40 1.950
12
11-2008
2.000
E T PS SL/Re MT/Re
2.050
2.100
2.150
2.200
Power Transmission Division
Dynamic Response to an AC Line-to-Ground Remote Fault – Inv. Side (Computer Simulation) PLOTS : Graphs UL1
UL2
UL3
100 75
AC Busbar Voltages
v_prim (kV)
50 25 0 -25 -50 -75 -100
250
VDC + 200 kV
US1
US2
US3
UdHP_B
UdHN_B
200 150
AC Converter Voltages
v_conv, v_dc (kV)
100 50 0 -50 -100 -150
VDC - 200 kV
-200 -250 1.20
DC Converter Current
IdHP_B
IdHN_B
1.00
Fault Ride-Through Capability i_dc (kA)
0.80 0.60 0.40 0.20 0.00 1.950
13
11-2008
E T PS SL/Re MT/Re
2.000
2.050
2.100
2.150
2.200
Power Transmission Division
HVDC PLUS – Grid Access for Renewable Energy Sources and Supply of Platforms and Islands
The Advanced MMC Technology DC DC Cable Cable Transmission Transmission DC DC Overhead Overhead Line Line Transmission Transmission Back-to-Back Back-to-Back Systems Systems Multiterminal Multiterminal Systems Systems STATCOM STATCOM Features Features included included 14
11-2008
E T PS SL/Re MT/Re
Power PowerTransmission TransmissionDivision Division
Trans Bay Cable Project, USA World’s 1st VSC HVDC with MMC-Technology
2010
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Transmission Constraints before TBC
Transmission Constraints after TBC
Elimination of Transmission Bottlenecks Energy Exchange by Sea Cable No Increase in Short-Circuit Power 15
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P = 400 MW Q = +/- 170-300 MVAr
11-2008
E T PS SL/Re MT/Re
Dynamic Voltage Support Power Transmission Division
Integration of large Offshore Wind Farms into the Main Grid – the German Prospects VSC HVDC – from Offshore to Land
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11-2008
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11-2008
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E T PS SL/Re
HVDC Classic – for Load & E T PSReserve SL/Re MT/Re Generation Sharing
Vattenfall Europe Transmission
Power Transmission Division Power Transmission Division
Synergies: SVC PLUS Solution
Seven Projects:
2009 - 2011
Rating: up to +/- 100 MVAr Dynamic Voltage Support 17
