vsc transmission tutorial
TRANSCRIPT
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18/09/2005 VSC Transmission Tutorial 1
CIGRE B4
HVDC and Power Electronics
HVDC Colloquium, Oslo, April 2006
VSC Transmissionpresented by
Dr Bjarne R Andersen,
Andersen Power Electronic Solutions Ltd
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 2
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCCHVDC technology,
- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 3
LCC HVDC Transmission
In use since 1954
- Long Distance transmission
- Asynchronous Interconnections
- >60GW in service, Voltage up to 600kVdc
Uses Thyristors,
- Line Commutated Converters
- Converter absorbs reactive power
- AC harmonic filters are used to achievesatisfactory waveshape and power factor
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 4
The Voltage Sourced Converter
- DC Voltage source
- Semi-conductors capable of turn-on AND
turn-off are used
- An ac voltage with controllable amplitude
and phase angle is produced.
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 9
VSC Start Up - 1
Diodes act as an uncontrolled rectifier.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 10
VSC Start Up - 2
Diodes act as an uncontrol led rectifier.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 11
IGBT Conducting - Inverter Operation.
VSC Operation - 1
What happens when we turn-off the IGBT??
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 12
IGBT Turned off - Diode picks up current
VSC Operation - 2
There will be a delay before the ac cur rent changes polarity because of L
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 13
Inverter Operation - Blanking Period has
passed and current has reversed.
VSC Operation - 3
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 14
VSC Operation - 4
Rectifier Operation
How do we turn off the diode?
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 15
VSC Operation - 5
Turning Off Diode - IGBT Conduction
causing a temporary short circuit
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 16
The diode turns off because of the short
circuit current
VSC Operation - 6
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 17
VSC Operation - 7
When the current in L reverses the
IGBT turns of f and the diode turns on
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 18
Full Wave Conversion
Advantages- Low Power Loss
Disadvantages
- AC and DC voltage relationship fixed - makes
it unsuitable for dc transmission
- High magnitude of low order harmonics - large
ac harmonic filters are required
0 1 2
dc
ac
dc
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 19
Pulse Width Modulation
Carrier at 9 times fundamental frequency
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 20
PWM Control
Disadvantage
- Power loss larger because of more frequent
switchingAdvantages
- Gives additional degrees of freedom - e.g.
independence of converters, and control of ac
voltage amplitude with fixed dc voltage
- Reduces lower order harmonics - smaller
filters- Higher speed of response
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 21
Simplified Representation
( )X
UUUQ
LL cosconv(1))1()1( =
sin.UL(1))1(
X
UP
conv=
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 22
Four Quadrant Control
The Reactive Power output depends on the
voltage ampli tude:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 23
Four Quadrant Control
The Active Power output depends on the
converter voltage Phase Angle:
U = Uconv L
P = 0 P < 0
UL
Iconv
LUU
conv
Iconv
conv conv
Uconv
-
Rectifier
operation
Inverter
operation
P > 0
conv
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 24
Rectifier
Mode
Inverter
Mode
CapacitiveInductive
Pconv
Qconv
Desired
Activ e
Power
Desired
ReactivePower
Uac = Max
Uac = Nom
Uac = Min
Four Quadrant Control
Simplified PQ Diagram
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 25
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCCHVDC technology,
- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,
- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 26
Comparison - Experience
LCC HVDC VSC Transmission
In service since 1954 In service si nce 1997
Installed Capacity >60GW Installed Capacity 930MVA
Largest Scheme 6300MW Largest Scheme 346MVA
Highest Voltage +/-600kVdc Highest Voltage +/-150kVdc
Reliability/Availability proven No formal records available at
present
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 27
Comparison - Converter
Technology
LCC HVDC VSC Transmission
Uses 8.5kV, 4kA Thyr isto rs, alatching device
Uses 2.5kV, 2kA IGBTs, atransistor type device
Turn on by control, turn offwhen current tries to reverse
Turn on by control and turn offby control, irrespective of thecurrent flow at the time
Requires AC network voltagefor commutation
Is self commutating Can bethe sole supply to a passivenetwork
Faults and switch operations inthe network can causecommutation failure
No Commutation Failures
Faults on the dc line cleared bythyristors through controlaction
The diodes feeds current intofault on dc side AC Circuitbreaker action needed to clear
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 28
Comparison - Harmonics
LCC HVDC VSC Transmission
12-pulse harmon ics (12n1),plus non-characteristic (2, 3, 4,
5, 7 etc )harmonics
PWM moves characteristicharmonics to higher orders
Requires large filters to limitharmonics typically on HVbus or on tertiary winding
Smaller and higher frequencyfilters required typicallybetween converter reactor andinterface transformer
Possibility of magnification ofpre-existing harmonics
Risk of magnification of pre-existing harmonics may besmaller, but needs evaluating
Switchable AC Harmonic Filtersalso used for Q Control Filter not normally switchable
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 29
Comparison - Reactive Power
LCC HVDC VSC Transmission
Converters absorb reactivepower (~55% of Real Power)
Converters can op erate at anyleading or lagging power factor.
Switchable AC Harmonic Filtersfor Q Control
Reactive Power can becontrolled by the converter
Large overvoltages can occurduring lo ad rejection
Load rejection overvoltage issmall
Site area is relati vely largebecause of need for switchableharmonic filters and shunt
capacitors
Site area is compact because ofsmall unswitchable filters andsimple ac switchyard
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 30
Comparison - Other
LCC HVDC VSC Transmission
Used with overhead lines,cables and mixtures thereof.
Al l co mmercial inst allat ionshave used cables so far.
Relatively low capital cost whenused at large power andrelatively strong ac networks
Competitive capital cost atpower
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 33
Benefits of Interconnections
Interconnection Benefits:
- Better utilisation of installed generation.- Reduction in overall spinning reserve.
- Emergency power support
The benefits f rom the use of HVDC include:
- The power flow is fully controlled.
- Asynchronous networks can be connected.
- HVDC is more economic when distance is
large, e.g. >800km overland or >70km
submarine.3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 34
Benefits of the use of cable
connections
It may be more expensive than an overhead
line but:- It is less intrusive on the landscape.
- It does not produce electric fields or varying
magnetic fields,
- More acceptable to the public, resulting in
planning approval being granted more quickly.
- It is not subject to flashover due to pollutionproblems,
- More reliable than an overhead line,
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 35
Interconnection to Small Isolated
network - 1
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 36
Interconnection to Small Isolated
network - 2
- No Electrical Power at present
- Small diesel generation at present Expensive MWhr cost,
Maintenance requirement,
Reliability/Availability,
Damaging for the environment
Reasons for Interconnection:
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 37
Interconnection to Small Isolated
network - 3
- No need for Synchronous Compensators- Converter can dynamically control the ac
system voltage
- Economic and environmental benefit by using
main network generation
- Less Maintenance
- Cable connection has low visual impact
Benefits from Using VSC Transmission:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 38
Interconnection between weak
networks - 1
~
=~
=
HVDC Line
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 39
Interconnection between weak
networks - 2
- Weak areas are likely to be remote from main
network. Provide damping control - improved security of
supply (fewer trips of ac line to main network)
- Asynchronous connection may be more
acceptable politically -(HVDC as Firewall)
- Converter can dynamically control the ac
system voltage - improved system stability.
Reasons for Interconnection:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 40
Re-inforcement of Weak AC tie
Lines - 1
~
=
~
= HVDC Line
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 41
Re-inforcement of Weak AC tie
Lines - 2
- More capacity needed.- As load grows, instabilities may cause frequent
trips.
- Power oscillations may reduce useable power
capacity.
- Unacceptable loop power flows.
- Controlability of HVDC may add substantialbenefits
Reasons for Re-inforcement:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 42
Re-inforcement of Weak AC tie
Lines - 3
- VSC Transmission can significantly increasethe available capacity on the ac Tie Line.
- Powerful damping control, through control of
active and reactive power.
ABB have shown that the capacity of a weak ac Tie
line can be increased by more than the rating of the
parallel VSC Transmission scheme
Benefits from Using VSC Transmission:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 43
Connection of Offshore loads - 1
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 44
Connection of Offshore loads - 2
- More capacity needed for extraction and
transport.- Reduction of maintenance compared with
GTs,
- Reduction of CO2 emissions
- Reduction of fire risks
Reasons for Connection:
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 45
Connection of Offshore loads - 3
- Does not require synchronous compensators,- Much lighter and more compact than LCC
HVDC,
- Can operate as a variable speed drive, for
large motors.
Benefits from Using VSC Transmission:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 46
Connection of Remote Wind
Farms - 1
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 47
Connection of Remote Wind
Farms - 2
- Transmission distance is large,
- De-coupling required between ac grid andwind farm ac network,
faults
power quality
- Enabling variable frequency of wind farm
network, for greater efficiency,
Reasons for Connection with HVDC:
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 48
Connection of Remote Wind
Farms - 3
- Connection can be made to weaker point in ac
network,- Improved stability of the wind farm ac network,
- Reduction of flicker on wind farm network
- Smaller site area required than for LCC HVDC
- Power can be transmitted to wind farm network
when the wind does not blow,
Auxiliary Power - Control & Protection, Tele-
communication, Navigation, Safety.
Benefits from Using VSC Transmission:
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 49
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCCHVDC technology,
- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,
- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 50
Components of a
VSC Transmission scheme
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 51
VSC - 3 phase implementation
3 phase 2-level Voltage Sourced Converter
d
d
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 52
PWM Control
Different PWM control methods:
- Triangular carrier, pure sinewave for control
- Triangular carrier, sinewave with 3rd harmonicfor control
- Optimised PWM - Selective harmonic
elimination
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 53
PWM - Waveshape & Harmonics
- 2
AC Volt age
phase to -
Neutral
Fundamental
frequency
component
Fourier
Analysi s of
Phase to
Phase
voltage
Triangular carrier at 21st harmonic, sinewave with 3rd
harmonic as control
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 54
OPWM / SHEM
Eliminates specific harmonics, but switching
instants change with operating conditions.- Pre-calculated or determined as you go
Can arrange to minimise switching at
maximum current
Results in a reduction in power loss,
compared with simple triangular carrier wave.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 55
PWM - Waveshape & Harmonics
- 3
AC Volt age
phase to -
Neutral
Fundamental
frequencycomponent
Fourier
Analysi s of
Phase to
Phase
voltage
Optimised PWM or Selective Harmonic Elimination
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 56
3-level (NPC), 3-phase VSC
Waveshape shown for fu ll wave switching
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 57
Advantages of multi-level
converters
Fewer switch operations for similar harmonic
performance. Lower voltage per switch.
Ampl itude of fundamental frequency vol tage
can be adjusted even with ful l wave switching
- giving additional degree of freedom.
Lower power loss.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 58
Pulse Width Modulation
0 90 180 270 360
1
0
1
Degree
Line-to-neutralvoltage(pu)
0 90 180 270 360
1
0
1
Degree
Line-to-neutralvo
ltage(pu)
2-Level VSC
3-Level VSC
PWM switching at 21 times fundamental frequency
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 59
Series connected 2-level
converters (HVDC Plus)
Converter
Transformer
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 60
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 61
VSC Valves - Device choice
Currently the device of choice is the IGBT
- Can be turned off in short circuit conditions.- Active control of the voltage across the device,
- Low power control of the device (Voltage
control - MOSFET device).
- High switching speed capability.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 62
IGBT Press Pack
- Valve operation with failed devices,
- Pack includes IGBTs and Diodes
- 6kV designs available, but 2.5kV, 2kA
devices generally used,
- Multi-chip design.
Illustration Courtesy of ABBIllustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 63
VSC Valve design - 1
Coherency of switch on and off is essential.
Voltage distr ibut ion control led by IGBT
transistor action Stray inductance kept as low as possib le
Voltage divider and surveillance circuits for
device monitoring
Energy for gate electronics obtained from
main circui t via voltage divider
Fibre optic interface with ground level control
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 64
VSC Valve design -2
A valve for 150kVdc may contain >300
series levels.
IGBTs and diodes are water cooled Devices mounted with great pressure against
heatsinks
Valves housed in metallic enclosure
- contains EMF
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 65
VSC Valve for 150kVdc
Photo Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 66
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 67
DC Capacitor Design
Provides energy storage on the dc s ide,
acting as a dc voltage source.
Capacitor must have low inductance Capacitor placed close to VSC Valves to
minimise stray inductance in commutating
loop
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 68
DC Capacitor
Capacitance must be large enough to l imit
harmonic ripple to design limit
- Ripple depends on direct current amplitudeand on the switching strategy
long pulses of high current causes more ripple
Voltage variations during faults in ac
networks also need to be taken into account.
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 69
DC Capacitor Design
Dry type capacitors used
- minimises fire risks Self healing metalised
film design used
Plastic Housing
Compact
Photo Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 70
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 71
Controls
Determines the instant at which each
individual VSC valve is switched on or off to
meet the operational requirements.
Typically:
- One station controls the direct voltage.
- One station controls the active power
- Both stations can also control ac voltage or
reactive power
Implemented as a dupl icated digital controlsystem.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 72
Control System Block Diagram
Figure Courtesy of ABB
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 73
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 74
Converter reactor
Provides constant fundamental frequency
impedance for the control of the VSC active
and reactive power output.
Provides a high frequency blocking filter
between the VSC and the ac network.
Limits rate of rise of short circuit currents.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 75
Converter reactor for 65MVA,
80kVdc VSC Transmission scheme
Dry type air-insulated
air-cored reactor
Typical impedance of
15%
Low st ray capacitance
Metallic screen to
eliminate external
magnetic fields
Forced air cooling
Photo Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 76
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 77
AC Harmonic Filter - 1
Characteristic harmonics tend to be at higher
orders.
Must check non-characteristic harmonics,
when the ac system can be unbalanced.
Design methods similar to those for LCC
HVDC scheme
Typical rating of the ac harmonic filter is 15%.
Typically includes tuned and high passbranches.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 78
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 79
Interface Transformer - 1
Enables the VSC to be designed
independently of the ac connection vol tage.
Blocks zero sequence current Provides additional series reactance
- beneficial for harmonics
- adds to converter reactor reactance
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 80
Interface Transformer - 3
Typically does not have dc stress or
significant harmonic stress.
- Ordinary substation transformer can be used.A converter winding tapchanger can achieve:
- larger steady state rating
- lower power loss
A tert iary winding may be used for auxi liary
power supply
Typical impedance of 10-15%
C t f
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Interface Transformer - 3
Photo Courtesy of ABBIllustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 82
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC Cables
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 83
DC Cables
Extruded polymeric cables can be used, as
the dc voltage does not change polarity.
- Lighter- Smaller bending radii
- No significant environmental risks.
These features make them easier and quicker
to install.
This type of cable has been proven in service
at voltages up to 150kVdc.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 84
Land Cables
Installed lengths of 1-
2km are joined in the
field.
Depending on theground conditions, cable
can be buried using
direct ploughing
methods.
Illustration Courtesy of ABB
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 85
Laying a Land Cable
Photo Courtesy of ABBIllustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 86
Deep Sea Submarine Cables
Can be manufactured
and laid in continuos
lengths of > 100km,depending on rating.
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 87
Components of a
VSC Transmission scheme
Converter Topology
VSC Valves
DC Capacitor
Controls
Converter Reactor
AC Fi lters
Interface Transformer
DC CablesOtherequipment/components
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 88
Other equipment in a VSC
Transmission substation
AC circuit breakers.
RFI and PLC fil ters.
Voltage and Current measuring transducers. Surge arresters.
Disconnectors and earth switches.
Auxi liary power suppl ies.
Fire Protection.
Civil works.
Ph i l L t 65 MVA
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 89
Physical Layout, 65 MVAHVDC LightTM Converter Station
Building
45 x 18 m
AC Yard &
Harmonic filters
Phase Reactors
Phase A, B and C valve enclosures
Auxiliary Power System
& Cooling Control
Cooling towers
DC Yard Equipment
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 90
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCCHVDC technology,
- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,
- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 91
System Issues - 1
Protection in ac network.
- During ac faults the current delivered by a VSC
Transmission scheme is limited to rated.- Conventional over-current protection may not
work.
- However, low current may permit longer fault
detection
- Protection needs careful consideration
- VSC Transmission does not add inertia Frequency tripping limits may need to be reassessed
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 92
System Issues - 2
Feasibility Studies can use third party
commercially available models.
- However, these models may not reflect fullcapability and/or limitations of the VSC.
- When specifying a scheme make the
specification functional, and provide necessary
system data.
- Studies done during feasibility phase typically
has to be repeated by the manufacturer duringthe implementation phase
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 93
System Issues - 3
When comparing options during feasibility
studies all issues must be considered:
Capital cost
Power Loss
Maintenance
Reliability
Availabi li ty
Operation cost
Anci llary service Benefi ts :
Reactive Power control,
Black Start Capability
Environmental Impact
Visual Impact
EMF
Time to In-service Public Enquiry
Time to implement
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 94
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCCHVDC technology,
- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,
- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 95
Gotland - the first commercial HVDCLightTM project
Technical Data
Commissioning year: 1999
Power rating: 50 MW
AC Voltage: 70 kV both endsDC Voltage: 80 kV
DC current 350 A
Length of DC cable: 2 x 70 km
Main reasons for choosing HVDC system: Wind power (voltage support ).
Easy to get permission for underground cables.
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 96
Gotland HVDC Light converter station at Ns, exterior view
Illustration Courtesy of ABB
Gotland HVDC Light
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 97
Converter station at
Ns blends in well with
surrounding farms.
Illustration Courtesy of ABBIllustration Courtesy of ABB
Gotland HVDC Light
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 98
Eagle Pass HVDC Light link
The HVDC Light i nstallation in Eagle Pass miti gates voltage instability , and
at the same time allows power exchange between the U.S. and Mexico.
Technical Data
Commissioning year: 2000
Power rating: 36 MW
AC Voltage: 132 kV (both sides)
DC Voltage: 15,9 kV
DC current 1,1 kA
Configuration: Back-to-back
Main reasons for choosing HVDC system: Controll ed asynchronous
connection for t rading. Voltage control
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 99
Eagle Pass HVDC Light,
simplified SLD
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 100
Eagle Pass converter st ation, AC yard.
Illustration Courtesy of ABB
Eagle Pass
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 101
Murraylink
Technical Data
Commiss ioning year: 2002
Power rating: 200 MW
AC Voltage: 132/220 kV
DC Voltage: 150 kV
DC current: 739 A
Length of DC cable: 2 x 180 km
Main reasons for choosing HVDC system: Controlled
asynchronous connection for trading. Easy to get permission
for underground cables.
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 102
Murraylink - valve enclosures
At factory
Placed on foundation
Inside building
Illustrations Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 103
Murraylink
Murraylink, the Berri converter station.
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 104
Technical Data
Commiss ioning year: 2002
Power rating: 330 MW AC
Voltage: 345 kV at New Haven138 kV at Shoreham
DC Voltage: 150 kV
DC cur rent 1175 A
Length of DC cable: 2 x 40 km
Main reasons for choosing HVDC system: Controlled
connection for trading. Submarine cables without oil.
Illustration Courtesy of ABB
Cross Sound Cable
C S d C LDynamic Response to Network
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 105
Building
90 x 18 m
Cross Sound Converter Layout
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 106
Dynamic Response to Network
Faults
March 17, 2005 Cross arm fault on 353 Line (345kV)
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 107
Dynamic Response to Network
Faults
Cross arm fault on 353 Line (345kV)Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 108
Troll A HVDC LightTM link
The HVDC LightTM install ation between the Norwegian main land and the Troll
A oil platform consists o f two ci rcui ts , each feeding a 40 MW compressor
motor
Technical Data
Commissioning year: Planned2004/2005
Power rating: 2 x 42 MW
AC Voltage: 132 kV/56 kV
DC Voltage: 60 kV
DC current 350 A
Length of DC cable: 4 x 70 km
Main reasons for choosing HVDC LightTM system: Environmental improvement
by elimination of gas turbines on platform. Low weight and small space on
platform. Ability to f eed and black-start motors, without local generation.
Illustration Courtesy of ABB
T ll A HVDC Li htTM li k T ll A
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 109
MotorFormer4-pole, 40MW0 - 65 Hz
56kV
Troll A
SM
70 km+/- 60kV
HVDC Light
138kV
Kollsnes
~
=
=
~
Troll A HVDC LightTM link
Illustrations Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 110
Troll A
Illustration Courtesy of ABB
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 111
Presentation Overview
- Basic Characteristics of VSC Transmission,
- Comparison of VSC Transmission and LCC
HVDC technology,- VSC Transmission Applications,
- Components of a VSC Transmission
Scheme,
- System Issues,
- Overview of VSC Transmission schemes,
- Future Trends.
3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 112
VSC Transmission Outlook
VSC Transmission has many technical
advantages over LCC HVDC
WG-37 has not identified any technicalreason why VSC Transmission cannot be
developed for very high voltage and power,
say 500kVdc, 3000MW
Main drawbacks relative to LCC HVDC are its
presently limited power rating and higher
power losses.
VSC Transmission trends Recommended Further reading
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3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 113
VSC Transmission trends
Future Developments
- Increased dc voltage (higher power, longerdistances)
- Increased dc current (higher power)
- New topologies (lower losses)
- New Semi-conductor devices (lower losses
and cost)
Resulting in:- VSC Transmission competing head on with
LCC HVDC in more and more applications.3rd April 2006 CIGRE B4 Meeting Oslo, April, 2006 114
Recommended Further reading
VSC Transmission, Cigre Brochure 269, Working
Group B4.37, April 2005.
Its Time to Connect, Technical Description of
HVDC Light technology, ABB website,
www.ABB.com/hvdc
18/09/2005 VSC Transmission Tutorial 115
Thank you for your Attention!
Any Quest ions?