dc Superconducting Power Transmission Line in Chubu University

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dc Superconducting Power Transmission Linein
Chubu University

• Presented by S. Yamaguchi
• yamax_at_isc.chubu.ac.jp

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• Contents
• Introduction of HTS Power cable
• Present status of ac power cable system
• DC Power Transmission System
• Proposal of dc superconducting power transmission
  system

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Start of ac Power Transmission
Started by Sumitomo in Japan

1. Replace of Copper cable
2. High current density of HTS cable
3. Low Cost of civil engineering
4. Good for Metropolitan Area, like New York Tokyo

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Present System of ac Power Transmission
superconducting ac cable
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Goal of ac Power Transmission
normalized loss
Low Loss Cable Main loss is due to AC
losses! Power is consumed by Cryo-cooler
goal
copper cable
HTS cable
4 times Higher _at_present time
From memo of Sumitomo in 1990s
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ac Power Transmission Projects
From memo of Sumitomo
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NEDO 500m Cable Project
2005
2001
Fiscal Year
Project is terminated March, 2005!
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Present Cable Projects in the World
US several projects in NY and Long
Island Korea KEPRI, now installing by
Sumitomo China InnoST Universities
These are all ac cable projects!
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Present Summary of ac HTS Cables

1. Reduce ac Losses 1/4 is required
2. Reduce the Cost 1/10 is required
3. Reduce heat leak 1/3 is required
4. Reduce Pressure Drop
5. How to re-start the National Project in Japan!

Review and Check Basic Ideas
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Proposal of dc SC transmission line
y0 Initial cost of ac Cu cable system y1
Initial cost of dc Cu cable system High
Inverter Cost x0 300 km for present
system y2 Initial cost of dc SC cable system
Inverter, Cryo-cooler Costs
for long distance, ac Cu cable lt dc Cu cable lt
dc SC Cable
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dc Power Transmission in World
Gotland 98km 260MW
Quebec-NewEngland 1486km 2250MW
Nelsonriver 240km 500MW
Vancouver
Ekibasutsuusu-centa 2400km 6000MW
Vienna 600MW
Ninamifukumitsu 300MW
Inter-mountain 785km 1920MW
Shyanghai 1046km 1200MW
Pacific intertie 1361km 1100MW
Crosschannel 70km 1000MW
Ultra high Voltage system Long distance
system Many system in all over the world
Newzealand 617km 1240MW
?????? OHM 1999 / 1 p.45 ?1????
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Development of Electric Power
US - GRID2030
300GW until 2020 dc transmission for long distance
China 150GW is underconstruction now. 18GW/year
until 2020
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dc transmission system

• Merit demerit
• Advantage for long distance
• High utilization factor
• Available for different frequency
• High cost by Inverter

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Low cost Inverter(1)
Development of low cost inverter - Application
of Hybrid cars Inverter
Battery- dc Motor -ac in Toyota Prius
VVVF inverter Low Cost ! Less than 1/10
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Low Cost Inverter(2)
Inverters of Electric Vehicle and Power Cables
dc power transmission High Voltage/series
connection EV Low Voltage / series and
parallel connection High switching freq.
? low higher harmonics ? high
efficiency low loss
? hard serial connection
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Low Cost Inverter(3)

• Inverter for SC Cable connection
• Thyrister is used for power transmission line,
  and its voltage and current are 4 kV and 3
  kA
• IGBT is used for EV, and its voltage and current
  are 1.7 kV and 100 A
• Ic of Bi-2223 tape is 100A in the present time
• Insulated and individual connection of the tape
  and the inverter is better to avoid the current
  imbalance and for the control and monitor.

EVs inverter is better for the parallel
connection of Inverter and HTS Tape, But higher
voltage is better now.
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dc Copper cable
Honshu-Hokkaido Power Cable, Japan
Ultra High Voltage 250kV Relative Low current
1kA Single Phase cable Oil Cooling Cable
Structure is similar to SC cable!
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Subjects of dc SC cable system

• Keep low temperature for long distance
• ?
• High Thermal Insulation
• Low Pressure Drop
• Low Cost Cable !

No ac Losses! High current density is achieved!
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Criticism of Sumitomos SC cable

• Electric Insulation isolate the SC from coolant
  
• Low Thermal Insulation
• High Pressure Drop

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Criticism of Furukawas SC cable

• No transport current in shield layer (high cost)
  
• Low Thermal Insulation
• High Pressure Drop

Hard to reduce the cost!
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Our design of SC cable

• No Shield Layer (low cost)
• High Thermal Insulation (electric and thermal
  insulator)
• Lowest Pressure Drop (Gas and oil pipe line
  structure)

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Connections of Current Lead, HTS tape and Inverter

• Management of Cable System
• Contorl of Strand Current (Insulated HTS tape)
• Small inverter connects insulated strand
• Monitor the individual voltage of Strand

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Connection of dc SC cable system

• dc Single Phase connection for SC cable
• and Low Cost!

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dc SC cable connection

• Management of Cable System
• Contorl of Strand Current (Insulated HTS tape)
• Small inverter connects insulated strand
• Monitor the individual voltage of Strand

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Electric Power Storage
Power Grid can Store Electric Power! High current
for Superconducting cable
high current and high inductance is better
to store the electric power
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Low Cost SMES Pipe Line

• Iron Core Pipe
• ?
• Magnetic Shield
• High Inductance
• Low Cost
• High Mechanical Strength

Storage Energy 230MJ for 20kA, 100km
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PCL application
High Current, but High heat Leak
Peltier Current Lead
f 0 f 1
copper lead 42.5 23.3
PCL 27.8 18.6
Heat leak for 77K unit(mW/A)
We plan not to use liquid N2 to reduce the heat
leak at current lead.
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Reality of dc SC cable system

1. Many dc Power Transmission Projects and Plan in
   US, China, Russia and Middle East
2. Low cost Inverter is developed in Japan
3. Enough high current density for Bi-2223 tape
   conductor
4. Need to develop cable cooling for long distance
5. Electric Power Storage function

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Present Experimental Plan

• Length lt 15 -20 m
• Current gt 2 - 4 kA
• 40 HTS Tapes of Sumitomo
• Ic gt 130 A _at_ 77K
• Voltage gt 10 - 30 kV
• Temp. lt 77K
• (sub-cool N2 slush N2)
• From 2005.4 to 2010.3

Layout in the experimental room
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Present Collaborations Goal

• Japanese several Universities
• materials, design, basic test experiment
• calculation
• Two Private Companies in Japan
• Cryo-cooler system, cryostat for cable

goal Re-start the National Project in Japan
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• Back to Edison !
• Use dc power !

Realize a Realistic SC System through Collaborati
on from all over the world!