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.”

Copyright MaterialsCopyright Materials

This educational activity is protected by U.S. and Internationalcopyright laws. Reproduction, distribution, display and use of theeducational activity without written permission of the presenter isy p p

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

yste

m AC P

AC

Pow

er S

yP

ower S

ystemte

m ACA

C P

ower

Sys

tC

Pow

er Systemm

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

eLVDC

AC

Pow

erer S

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