Electrical Considerations for HVDC Transmission Lines Joe Moone PE
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• Identify the electrical requirements for HVDC lines. •
en y
e componen s use
n
o
convers on.
of HVDC HVDC conversion and transmission • Understand the history of of HVDC HVDC conversion technology. • Understand the operation of
• Understand the requirements of of an an HVDC convertor station. • Understand the differences between classic HVDC and new HVDC technology. • Understand the fundamental requirements of of HVDC HVDC transmission line design. •
Understan Understand d the insulation insulation re uirements uirements for for an HVDC line.
HVDC A Brief History • – Gotland, Sweden –
,
,
• First Installation in North America in 1969 – Vancouver Island, BC – ±260kV, 312MW, 46miles of submarine cable
HVDC A Brief History •
‐ – Pacific DC Intertie ‐ 1970 –
,
– Currently at 3100MW, ±500kV
Graphic Courtesy ABB Photo Courtesy ABB
HVDC A Brief History –
•
– Democratic Republic of Congo, Africa –
,
,
,
• Highest Voltage in Operation ‐ ±600kV
Graphic Courtesy ABB
– Itaipu, Brazil – 1987, two circuits@3150MW each, 490+ miles
Graphic Courtesy ABB
HVDC A Brief History •
‐ – Quebec‐New England –
,
,
• Longest Submarine Cable – Norway to Netherlands – 362 Miles – 2008, ±450kV, 700MW
Graphic Courtesy ABB
HVDC A Snapshot of the Future • Highest Voltage ‐ ±800kV – Two c rcu ts n C na – 5000MW, 890 miles (2010) – 6400MW, 1295 miles (2011)
Graphic Courtesy ABB
Graphic Courtesy Siemens
• Longest Circuit – Over 1550 miles – Rio Maderia in Brazil – ±600kV, 3150MW – Scheduled to be in operation in 2012 Graphic Courtesy ABB
• Long Distance • Asynchronous Systems • Controlled Power Transfer • Reduce Right‐of ‐Way
HVDC Pro ects Planned in China
Source: MarketAvenue
6000MW ‐ HVDC vs. AC
‐ ‐ ±500kV DC
500kV AC
±500kV vs. 500kV AC
±800kV vs. 800kV AC
Graphic Courtesy ABB
• – Line Current Commutated; Thyristors ’
–
– High voltage applications; ±800kV
•
g – Voltage Source Commutated; IGBT – Small blocks of power; 100’s of MW – Lower voltages; ±200kV
• • • • •
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
Photos Courtesy Siemens
Photos Courtesy ABB
Photos Courtesy ABB
Photo Courtesy ABB
• • • • •
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
Photos Courtesy ABB
Photos Courtesy ABB
• – Single positive dc voltage (e.g., +500kV) •
– Neutral return • • Earth return through ground electrode
– Limited O eration • Fault or maintenance results in outage
Mono ole HVDC m e t s y S r e w o P C A
m e t s y S r e w o P C A
A C P o w e r S y s t e m
A C P o w e r S y s t e
• – 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 • Allows for maintenance or outage of one pole • Up to half of rated power output
Bipole Operation Earth Return HVDC Cable/OH Line
m e t s y S r w o P C A
Earth Return Ground Electrode
HVDC Cable/OH Line
A C P o w e r S y s t e m
Bipole Operation Metallic Return HVDC Cable/OH Line
m e t s y S r e w o P C A
LVDC Cable/OH Line
HVDC Cable/OH Line
A C P o w r S y s t e m
Cost Comparison HVDC vs. AC • converter stations and filtering requirements. of an AC line.
• Long AC nes are more expens ve ue to s unt and series compensation requirements.
• • Metallic or earth return (ground electrode) • Au i e Noise • Magnetic and Electric Fields
• – Switching Performance –
• Altitude • Pollution/Contaminants
Air l 8
r n
– Switching – primary
2.6 p.u. 6
– Lightning – secondary
1.8 p.u.
2
HVDC
0 500
8
ir m n
EHV AC
EHVAC Air Clearance Requirements (meter)
4
R
800 System vol tage (kV)
1100
HVDC Air Clearance Requirements (meter)
are Significantly Lower for .
2 0
Graphic Courtesy ABB
–
– Lightning – primary
4
400
–
600 System vol tage (±kV)
800
Relative increase in insulation requirements with altitude
EHV AC
1.30
– r earance (switching)
Lightning
1.25
Switching Pollution
1.20
– Insulation
1.15
ollution
HVDC
1.10
– Air Clearance (lightning)
. 1.00
– Insulation (creepage)
0.95 0.90 0 Graphic Courtesy ABB
500
1000
1500
Altitude (meter)
2000
Insulation Requirements for HVDC are More v u
• – Same current rating as main conductor –
• Earth Return – Expansive ground electrode – Requires significant study • Gravity survey, hydrological survey, electrical resistivity survey, geological modeling
IPP Southern Electrode
roun Electrode Connection to
• for HVDC Lines Reduced for HVDC Lines to Meet Audible
Typical cor ona losses (kW/km) Frost
Rain
Fair
1000 EHVAC
100 HVDC
1 Graphic Courtesy ABB
EHVAC, HVDC
Altitude (m)
Corona Losses on HVDC are less Sensitive to Weather Conditions
UHVAC Conductor Bundles for 55dB Maximum 2000
6
6
9
Altitude (meter) 1000
5
6
8
4
5
8
500 0 700
800
900
1000
1100
System voltage (kV) Graphic Courtesy ABB
HVDC Conductor Bundles for 45dB Maximum 7
2000
Altitude (meter)
1500
500
2
4
5
6
2
3
4
5
0
System voltage (±kV) Graphic Courtesy ABB
• • Current flow in Opposite Directions Cancel – Comparable to Earths Magnetic Field (50µT)
• Field Requirements for DC are less Stringent than AC – Greater Public Acceptance…
Itaipu HVDC and EHV System HVDC Line Cost about 70% of AC Line
ITAIPU 2 x 6300 MW
3 x 765 kV AC, 2 intermediate S/S 6300 MW with SC 4500 MW without SC c rcu s
2 x ± 600 kV DC 6300 MW, 2 converters per pole 4700 MW with pole outage po es
Photo Courtesy ABB
Itai u 765kV Ac Lines Line 1. 891 km 1982, 86, Line 2. 891 km 1989 Line 3. 915 km 1999, 00, 01 • About
70% Guyed Vee
• Avera
e wei ht 8500 k
• Self supporting,
weight 14000 kg
• 15.80
m Phase spacing, guyed
• 14.30
m Phase spacing, self support
• Conductor
4xBluejay 564 mm² ACSR
•
Photo Courtesy ABB
u ed
•
35 Insulators
•
95 m RoW one line
•
178 m RoW two lines
Bipole 1792 km Bipole 2820 km
1984 1987
• • Average
weight 5000 kg, guyed
• Self supporting, • Conductor
4xBittern 644 mm² 45/7ACSR
•
450 mm subconductor spacing
•
32 Insulators 510 mm creep, 27 mm/kV
• 16.40 •
Photo Courtesy ABB
weight 9000 kg
m pole spacing
