SMES

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SMES Fly Wheel
43421315 ???
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Introduction (1)
Power supply system

• Base Nuclear power generation
• Middle Thermal power generation
• Peak Hydro electronic power generation

Utilization rate 5060
Near future
The demand for the load leveling of electric
power will increase
New energy storage system will be necessary

• Storage devices of the energy

Superconducting magnetic energy storage
(SMES) Fly wheel motor generator
Advantages Utilization rate increase
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SMES
Superconductivity
Meissner effect
Electric resistance Nothing
Current Large , permanently
Circuit model of the SMES
Storing electrical energy as magnetic energy
Discharging
Charging
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SMES
Charging
Discharging
Operating
- V
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Fly Wheel
Principle
Electric energy
charging
Motion energy
discharging
Electric energy
Bearing
Rotation loss
Friction resistance
Efficiency
High
(A few watts /kg)
Mechanical bearing
Low
Large
High
Nothing
Low
(10-210-3watts /kg)
Magnet bearing
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Fly Wheel
Storage energy E
Shape factor,
Volume
Stress to direction of circumference due to
rotation,
Weight of fly wheel W
weight volume ratio
Large
Fly wheel volume
Light
Weight of fly wheel
Large
Storage energy E
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Introduction (2)

• Comparison of power storage systems

Application
Load leveling,Power system stabilization etc
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Technological opportunity
SMES

• Development for the larger superconducting
  magnet
• Development for the switch for the great
  current
• Measuring to protect superconducting coil

AC loss (eddy current loss)
Fly Wheel

• Optimizing design for the Fly wheel

lightweight, large-size,etc

• Development for the axle bearing

low loss, etc

• Measures to rotate flywheel with stability

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Analysis of eddy current losses during
discharging period in a 600 kJ SMES
M.J.Park, S.Y.kwak, S.Y.Lee, W.S.Kim, J.K.Lee,
C.Park, K.Choi, J.H.bae, S,H.Kim, K.D.Sim,
K.C.Seong, H.K.Jung, S.Hahn
43421315 Katsuhito Kataoka
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Introduction
SMES with HTS wires have been developed
world-wide.
A 600 kJ class HTS SMES system in Korea

• Power quality compensation
• Stabilization of the power grid

A 600 kJ class SMES magnet

• Type A single pole solenoid type
• Component 22 double pancake coils
• Capacity 615kJ
• Operating temperature 20K

GM cryo-coolers
First stage ? the HTS current leads, thermal
shield
Second stage ? the cooling plates
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Introduction
Decreasing patterns of current and energy of SMES

• Operating current

275 A ? 138 A
The operation of SMES system

• Stored energy

• Charging
• Storing
• Discharging

615 kJ ? 150 kJ
Analysis
By using 3D FEM (Finite Element Method)
The discharging time short
Eddy current losses

• In cooling plates
• In a heat sink
• In a thermal sink

The eddy current bigger
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1.Eddy current losses in the cooling plates
No division No slit
140320 kW ( the cooling capacity)
10 kW
some division and slits
Reduce the eddy current loss
increase
decrease
Number of the divisions and slits
large
The eddy current loss
small
Considering mechanical intensity, weight ,etc
Long slits Not creating complete divisions
Bock off eddy current path
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1.Eddy current losses in the cooling plates
Analyzing the eddy current losses of three
plates
The 11th from the bottom of the magnet
The 17th from the bottom of the magnet
The 22th from the bottom of the magnet
The cross section of the double pancake coil
5.97 W
The total eddy current losses ? 103.8 W
(estimated)
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2.Eddy current losses in the heat sink
The primary purpose
The heat sink
Collecting and transmitting heat through the
cooling channel up to the cooler
Cooling down the magnet
The heat sink
The magnet
Temperature 20 K
Analysis model for FEM
Heat conductivity
Great
Eddy current losses increase steadily
Two equal parts
Steadily increase

• Cutting eddy current path
• Sharing thermal load from magnet equally

Analysis conclusion
Eddy current loss of heat sink
87.45 J (total during the discharging time)
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3.Eddy current losses in the thermal sink
Result of the analysis
the pattern of the losses
Steadily increase

• Side of the thermal shield nearest to the magnet

More eddy current flow and disturb

• Eddy current loss of the thermal sink

15 kJ (total during the discharging time)
much higher
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Conclusion
Calculating the eddy current losses for 3 seconds
(discharging time) by FEM
The cooling pates of magnet

• The losses of the cooling plates in
• the magnet for 600 kJ SMES

103.8 W
The loss of the heat sink
87.45 J
The thermal sink
15 kJ
The heat , thermal sink
Steadily increase
The eddy current losses
Difference of time constant due to conductivity
of the material by temperature
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REFERANCE

• ?? ??,??????????,???? (2005)
• M.J.Park, S.Y.kwak, S.Y.Lee, W.S.Kim, J.K.Lee,
  C.Park, K.Choi, J.H.bae, S,H.Kim, K.D.Sim,
• K.C.Seong, H.K.Jung, S.Hahn, Analysis of eddy
  current losses during discharging period in a
• 600 kJ SMES (2008)
• ? ??,?????? Vol.35 No.6,????????????????????
  (1998)
• ISTEC ??????????,??????????,?????? (1996)