John Strauss Siemens AG. John.Strauss@Siemens · Offshore Windfarm Grid Access by HVDC ... • VSC...
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Transcript of John Strauss Siemens AG. John.Strauss@Siemens · Offshore Windfarm Grid Access by HVDC ... • VSC...
VSC-HVDC with MMC – Basic Scheme
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Phase Unit
Vd
IGBT2D2
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Power Module (PM)
Power Module Electronics (PME)
Converter Arm
Converter Reactors
Converter ModuleReference HVDC PLUS
The Result: MMC – a perfect Voltage Generation
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AC and DC Voltages controlled by Converter Arm Voltages:
VAC
Benefits of VSC-HVDC
HVDC PLUS
HVDC “Classic”
Space Saving
HVDC PLUS Example 400 MW
Basic Features of MMC Technology
The reactive power can be controlled to any value within the limiting characteristics
As little as 20 modules per phase will already meet IEC/IEEE limits without AC harmonic shunt filters.
MMC topology - Features and Benefits
Low semiconductor switching frequency
Low generation of harmonics
High modularity in hardware and softwareUse of well-proven standard componentsSinus shaped AC voltage waveforms
Easy scalability
Reduced number of primary components
Low converter losses
No Harmonic / PLC / Radio interference filtering required High flexibility, economical from low to high power ratings High availability of state-of-the-art components Use of standard AC transformers
Low engineering efforts
High reliability,low maintenance requirements
Reference from HVDC PLUS -Win-TDC with PLUSCONTROL
PLUSCONTROL
MMS nMMS 1
SCADA Interface
C&P Level
Operator Level
Switchgear & Auxiliaries Voltages & Currents Converter – Power Modules
SCADA Interface
RCIRCI
I/O Unit I/O Unit
I/O Level Measuring System
Remote HMI Local HMI
CCS
SIMATIC TDC
Win-TDC
SIMATICWinCC
Current Control System
Module Management System
MMC Controls - Features and Benefits
Current reversal possible with no minimum holding currents
Full output vector controls
Uni-polar DC voltage
Very Fast Closed Loop Control
Allows for precise power flow control down to Zero MWAllows for independent control of Active and Reactive PowerGood for Cable and Multi-Terminal applications
Allows for Fault Ride Through (FRT) and fault current inject
Flexible Control Mode Coord.(P-Q / U-F / Multi-Term)
Allows for even Faster (Linear) Power Reversal without Blocking of the Converters.
Full primary U/F controls Used for Black Start of Offshore grids (as well as SRAS)
Fault Ride Through (FRT) –Transbay Cable (Inverter Station)
Fast Power Reversal –Simulated (based on TBC)
VDC - 200 kV
VDC + 200 kV
AC Converter Voltages
DC Converter Current
Six Converter Arm Currents
Currents at the AC Terminals
PDC + 200 MW
PDC - 200 MW
Offshore Windfarm Grid Access by HVDCControl Requirements
The offshore converter station is the master device of the offshore grid
The converter must be able to control the offshore frequency andvoltage
Blackstart is required – basically no stable offshore ‘grid‘ at all
Windfarm starting up or idling
Windfarm generating power
Frequency and voltage control have to work for both power flow directions:
Offshore Grid Control: 3p Offshore Fault Short Circuit Current Contribution
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Offshore Rectifier Onshore InverterAC Voltages
Active & Reactive Power
DC Voltage
DC Current & Offshore Frequency
DC Current
1.2 pu Short Circuit Current
AC Currents
Q Support Onshore (Loss of generation)
DC Voltage
Offshore Windfarm Grid Access with HVDCBraking Chopper at Onshore Converter Station
DC side braking chopper
absorbs dynamic excess power generated by the Windfarm during onshore grid interruptions
For enduring grid faults, the Windfarm may be throttled down in usual order, via Winfarm power control – no emergency shut-downThe Chopper is installed at the onshore converter station,the offshore station‘s footprint is not enlarged.
Windfarm will take no notice of short onshore grid interruptions
3p Onshore Fault Smooth Chopper Operation
Offshore Rectifier Onshore Inverter
AC Voltages
Active & Reactive Power
DC Voltage
DC Current & Offshore Frequency
Smooth DC Voltage & Current
DC Current& Chopper Current
Modular Braking Chopper – Features and Benefits
Smooth DC voltage and current
Redundant design
Use of well-proven standard components
Easy scalability
Low number of primary components
Save fault ride through of offshore windfarm
High reliability
High availability of state-of-the-art components
Low engineering efforts
Low maintenance requirements
Conclusion
• Uni-polar HVDC is best suited for DC Cable, Multi terminal and DC grid application.
• VSC-HVDC System is the state-of-the-art DC transmission technology to provide grid access to large offshore wind parks and renewable energy supplies.
• VSC-HVDC System (as bulk power transmission system) is suitable for interconnecting AC Grids.
• VSC with MMC will be an integral part of future transmission systems.
