electrical considerations for hvdc transmission lines
DESCRIPTION
these are the general electrical considerations that are taken in a hvdc transmission lineTRANSCRIPT
Electrical Considerations for HVDC Transmission Lines
Joe Mooney, PEy,
“POWER Engineers has met the standards and requirements of theRegistered Continuing Education Program. Credit earned oncompletion of this program will be reported to RCEPP. A certificate of completion will be issued to each participant. As such, it does not p p p ,include content that may be deemed or construed to be anapproval or endorsement by NCEES or RCEPP.”
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prohibited.
© POWER E i 2009© POWER Engineers 2009
Learning ObjectivesLearning Objectives
At the end of this presentation you will be able to:At the end of this presentation you will be able to:
• Identify the electrical requirements for HVDC lines.
Id tif th t d i AC t DC i• Identify the components used in AC to DC conversion.
• Understand the history of HVDC conversion and transmission
• Understand the operation of HVDC conversion technology.
• Understand the requirements of an HVDC convertor station.
• Understand the differences between classic HVDC and new HVDC technology.
• Understand the fundamental requirements of HVDC transmission line design.
• Understand the insulation requirements for an HVDC line.Understand the insulation requirements for an HVDC line.
HVDCA Brief History
• First HVDC System Commissioned in 1954First HVDC System Commissioned in 1954– Gotland, Sweden
±100kV 20MW 60miles of submarine cable– ±100kV, 20MW, 60miles of submarine cable
• First Installation in North America in 1969– Vancouver Island, BC
– ±260kV, 312MW, 46miles of submarine cable
HVDCfA Brief History
• Last Mercury‐Arc Valve InstallationLast Mercury Arc Valve Installation– Pacific DC Intertie ‐ 1970
1440MW ±400kV– 1440MW, ±400kV
– Currently at 3100MW, ±500kV
Graphic Courtesy ABB
Photo Courtesy ABB
HVDCfA Brief History
• Longest Distance in Operation – 1062 milesLongest Distance in Operation 1062 miles– Democratic Republic of Congo, Africa
1983 ±500kV 560MW overhead line– 1983, ±500kV, 560MW, overhead line
• Highest Voltage in Operation ‐ ±600kV Graphic Courtesy ABB
– Itaipu, Brazil
– 1987, two circuits@3150MW each, 490+ miles
Graphic Courtesy ABB
HVDCfA Brief History
• First Multi‐Terminal HVDC SystemFirst Multi Terminal HVDC System– Quebec‐New England
1992 ±450kV 2000MW– 1992, ±450kV, 2000MW
• Longest Submarine Cable– Norway to Netherlands
– 362 Miles
– 2008, ±450kV, 700MWGraphic Courtesy ABB
HVDC h f hA Snapshot of the Future
• Highest Voltage ‐ ±800kVT i i i Chi– Two circuits in China
– 5000MW, 890 miles (2010) Graphic Courtesy ABB
– 6400MW, 1295 miles (2011)
• Longest Circuit – Over 1550 milesGraphic Courtesy Siemens
– Rio Maderia in Brazil
– ±600kV, 3150MW
– Scheduled to be in operation in 2012Graphic Courtesy ABB
When to Use HVDCWhen to Use HVDC
• Long Distance
• Long Underground/Submarine Cables• Long Underground/Submarine Cables
• Asynchronous Systems
• Controlled Power Transfer
• Reduce Right‐of‐Wayg y
HVDC Projects Planned in Chinaj
Source: MarketAvenue
6000MW ‐ HVDC vs. ACRight of Way ComparisonRight‐of‐Way Comparison
±500kV DC
500kV AC
±500kV vs. 500kV AC
±800kV vs. 800kV AC
Typical HVDC Converter StationTypical HVDC Converter Station
Graphic Courtesy ABB
HVDC TechnologyHVDC Technology
• HVDC ClassicHVDC Classic– Line Current Commutated; Thyristors
Large blocks of power; 1000’s of MW– Large blocks of power; 1000 s of MW
– High voltage applications; ±800kV
HVDC Li ht/PLUS• HVDC Light/PLUS– Voltage Source Commutated; IGBT
– Small blocks of power; 100’s of MW
– Lower voltages; ±200kV
HVDC Classic DesignHVDC Classic Design• Twelve Pulse Converter• Requires Specially Designed Transformers• Power System Must Supply Reactive Power• Thyristors are Switched on and turned off by reverse voltage • Harmonic Filters are required
HVDC Classic Valve GroupsHVDC Classic Valve Groups
Photos Courtesy Siemens
HVDC Classic Converter TransformerHVDC Classic Converter Transformer
Photos Courtesy ABB
HVDC Classic AC FiltersHVDC Classic AC Filters
Photos Courtesy ABB
3000MW HVDC Classic Station3000MW HVDC Classic Station
Photo Courtesy ABB
HVDC Light DesignHVDC Light Design• Insulated Gate Bipolar Transistors• “Off‐the‐shelf” transformer• Switched on and off – Pulse Width Modulation• Power factor can be controlled• Simple high‐pass filter for high order harmonics
Graphic Courtesy ABB
HVDC Light ComponentsHVDC Light Components
Photos Courtesy ABB
HVDC Light StationHVDC Light Station
Photos Courtesy ABB
HVDC OperationHVDC Operation
• MonopoleMonopole– Single positive dc voltage (e.g., +500kV)
• One high voltage conductorOne high voltage conductor
– Neutral return• Metallic return via low voltage conductorMetallic return via low voltage conductor
• Earth return through ground electrode
– Limited Operationed Ope a o• Fault or maintenance results in outage
Monopole HVDCp
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ystemte
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HVDC OperationHVDC Operation
• BipoleBipole– Positive and negative voltage (e.g., ±500kV)
• Two high voltage conductors
– Neutral return• Metallic return via low voltage conductor• Earth return through ground electrode
– Best Operational Flexibility• Operate in monopole configuration as needed• Operate in monopole configuration as needed• Allows for maintenance or outage of one pole• Up to half of rated power outputp p p
Bipole OperationhEarth Return
HVDCCCable/OH Line
er S
yste
mAC
Powe
AC P
owe
er SystemEarth Return
Ground Electrode
HVDCCable/OH Line
Bipole OperationllMetallic Return
HVDCHVDCCable/OH Line
r Sys
tem
AC
Pow
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AC
Pow
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ystem
Cable/OH Line
HVDCCable/OH Line
Cost ComparisonHVDC vs. AC
• HVDC has a higher installation cost due to theHVDC has a higher installation cost due to the converter stations and filtering requirements.
• The cost of an HVDC line is less than the cost• The cost of an HVDC line is less than the cost of an AC line.
L AC li i d h• Long AC lines are more expensive due to shunt and series compensation requirements.
Cost vs. Distance for HVDC and ACCost vs. Distance for HVDC and AC
Electrical ConsiderationsElectrical Considerations
• InsulationInsulation
• Metallic or earth return (ground electrode)
dibl i• Audible Noise
• Magnetic and Electric Fields
Insulation RequirementsInsulation Requirements
• Air Clearance RequirementsAir Clearance Requirements– Switching Performance
Lightning– Lightning
• Altitude
• Pollution/Contaminants
Air Clearance RequirementsAir Clearance Requirements
EHV ACEHVAC Air Clearance Requirements (meter)8
– Switching – primary
– Lightning – secondary4
62.6 p.u.
1.8 p.u.
HVDC– Switching – secondary
0
2
500 800 1100System voltage (kV) Switching secondary
– Lightning – primary
Air Clearance Requirements
y g ( )
HVDC Air Clearance Requirements (meter)
6
8
Air Clearance Requirements are Significantly Lower for HVDC2
4
6
HVDC.0400 600 800
System voltage (±kV)Graphic Courtesy ABB
Effect of AltitudeEffect of AltitudeEHV AC
Ai Cl1.30
Relative increase in insulation requirements with altitude
– Air Clearance (switching)
– Insulation (pollution)1.20
1.25LightningSwitchingPollution
(p )
HVDC– Air Clearance 1 05
1.10
1.15
(lightning)
– Insulation (creepage)0.95
1.00
1.05
Insulation Requirements for HVDC are More Sensitive to Altitude
0.900 500 1000 1500 2000
Altitude (meter)Graphic Courtesy ABB
Sensitive to Altitude
Earth ReturnEarth Return
• Metallic ReturnMetallic Return– Same current rating as main conductor
Insulated for voltage drop caused by current flow– Insulated for voltage drop caused by current flow
• Earth Return– Expansive ground electrode
– Requires significant study• Gravity survey, hydrological survey, electrical resistivity survey, geological modeling
IPP Southern Electrode
IPP HVDCIPP HVDC
G dGround Electrode
Connection to TowerTower
Corona and Audible NoiseCorona and Audible Noise
• Weather has Smaller Effect on Corona LossesWeather has Smaller Effect on Corona Losses for HVDC Lines
• Requirement for Conductor Bundling is• Requirement for Conductor Bundling is Reduced for HVDC Lines to Meet Audible Noise RequirementsNoise Requirements
Corona and Audible NoiseCorona and Audible Noise
Typical corona losses (kW/km)
1000Frost Rain Fair
EHVAC
Corona Losses on HVDC are less
10
100HVDC
HVDC are less Sensitive to Weather Conditions
1
10
0 500 1000 1500 2000
EHVAC, HVDC
0 500 1000 1500 2000Altitude (m)Graphic Courtesy ABB
UHVAC Conductor Bundles for 55dB Maximum
6 6 9
1500
2000
65 8
Altitude (meter) 1000
1500
8
50054 8
0700 800 900 1000 1100
System voltage (kV)Graphic Courtesy ABB
HVDC Conductor Bundles f dfor 45dB Maximum
73 64 73 64
2000
642 5Altitude (meter)
1000
1500
2 3 54500
1000
3 4
0400 500 600 700 800400 500 600 700 800
System voltage (±kV)Graphic Courtesy ABB
Magnetic and Electric FieldsMagnetic and Electric Fields
• No Magnetic Induction from DCNo Magnetic Induction from DC
• Current flow in Opposite Directions Cancel Magnetic Field Effect on HVDCMagnetic Field Effect on HVDC– Comparable to Earths Magnetic Field (50µT)
• Field Requirements for DC are less Stringent than AC– Greater Public Acceptance…
Itaipu HVDC and EHV SystemHVDC Line Cost about 70% of AC Line
ITAIPU2 x 6300 MW6300
3 x 765 kV AC, 2 intermediate S/S6300 MW with SC
4500 MW without SC3 i it
2 x ± 600 kV DC6300 MW, 2 converters per pole4700 MW with pole outage
4 l3 circuits 4 poles
Photo Courtesy ABB
Itaipu 765kV Ac LinespLine 1. 891 km 1982, 86, Line 2. 891 km 1989Line 3. 915 km 1999, 00, 01
• About 70% Guyed Vee
• Average weight 8500 kg, guyedAverage weight 8500 kg, guyed
• Self supporting, weight 14000 kg
• 15.80 m Phase spacing, guyed
• 14.30 m Phase spacing, self support
• Conductor 4xBluejay 564 mm² ACSR
450 mm subconductor spacing• 450 mm subconductor spacing
• 35 Insulators
• 95 m RoW one line
• 178 m RoW two linesPhoto Courtesy ABB
Itaipu ±600kV HVDC LinesItaipu ±600kV HVDC Lines
Bipole 1792 km 1984Bipole 2820 km 1987
About 80% Guyed Mast• About 80% Guyed Mast
• Average weight 5000 kg, guyed
• Self supporting, weight 9000 kg
• Conductor 4xBittern 644 mm² 45/7ACSR
• 450 mm subconductor spacing
• 32 Insulators 510 mm creep, 27 mm/kV
• 16.40 m pole spacing
• 72 m RoW per circuit72 m RoW per circuit
Photo Courtesy ABB
Thank you for your time.
QUESTIONS?QUESTIONS?This concludes the educational content of this activityThis concludes the educational content of this activity.
Joe Mooney, P.E.Sr Project ManagerSr. Project Managerwww.powereng.com
March 2010