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ASIPP
EAST
PF Coils Quench Protection Design of EAST
Superconducting Tokamak
Oct. 5, 2005
PF power supply team
Institute of Plasma Physics,Chinese Academy of Sciences
Hefei Anhui 230031
P.R.China
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PF Coil Distribution
The whole EAST PF
magnet system consists
of 14 coils, among them
PF1 to PF6 are the CS
coils, PF7 to PF10 are the
diverter coils, and PF11
to PF14 are the PF big
coils. They located
symmetrically around the
equatorial plane
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PF Coil current in EAST operation
I (KA)
t (s)
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The connection between PF coils and PFPS
PS1
PS3
PS5
1#
3#
5#
7#
2#
4#
6#
8#
PS2
PS4
PS6
PS7
PS8
PS9
PS11
9#
11#
13#
10#
12#
14#
PS10
PS12
The PF system consists of 14 upper and lower SC coils
around the plasma in the EAST tokamak, due to the series
connection in diverter, 12 set of PFPS is essential.
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Parameter for PF Magnet and Plasma Operation
Nominal cycle period
PF magnetization
PF dwell time to keep magnetization
Plasma initiation
Plasma current ramp up
Maximum plasma flat top
Plasma current ramp down
2800 s
20 s
20 s
0.06 s
4s
1000 s
4s
Tab. 1 EAST PF magnet parameters
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PF Coil Parameters and Requirements
Rated current
Excited time
Voltage (terminal to terminal)
Voltage (magnet to ground)
Limited heat condition
Quench protection delay
Self inductance
Mutual inductance
Storage energy in operation
15kA
20s
10000V
10000V
5.1108 A2s
1s
17.6~129.5mH
0.33~ 21.6mH
42MJ (max. 140MJ)
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The power supply circuit of EAST PF coil
F
D
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The requirements of quench protection
★ to discharge the magnets in such a way that is less than
a prescribed limit under all conditions;
★ to limit the maximum instantaneous voltages imposed
on the magnet (terminal to terminal, and terminal to
ground);
★ to ensure successful discharge with a prescribed
reliability for a given number of events over the design
lifetime.
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QP Feature for PF Coil
★ Frequent switching off. the high current rate, and plasma
disruption in operation, The PF coil has possibly more quench,
★ strong coupling. The 12 pairs of coil have strong decoupling in
each other, in QP the coil energy dissipation will be different from
single coil.
★ Positive and negative current. in PF coil,it is important for QP
design to use artificial current zero technology
★High power in input power supply. In PF magnet system, the
primary power supply usually is quite high voltage, therefore it is
necessary to suppress the input power supply in QP
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PF Coil Storage Energy
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PF Coil Storage Energy for Each energy
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不同运行方式下各线圈最大储能 （MJ）
托卡马克运 1，2
行方式\线圈
号
大拉长运行 3.8
3, 4
5, 6
7,8
9,10
4.3
3.4
2.4
12.1 3.0
大截面运行
3.8
4.3
3.4
0.73 3.5
3.9
1.4
大体积运行
3.8
4.3
3.4
1.75 9.1
5.5
1.03
最大能量
3.8
4.3
3.4
2.4
11,12
12.1 5.5
13,14
2.6
2.6
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QP System configuration
CU1 CU2
D
F
2
2
P
DCCT
The QP consists of bypass, DCCB, PB, fuse, resistor
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QP Operation Scenario
★ Bypass primary PS.
Upon command, the quench protection
system will suppress the power supply, close the bypass CU3.
★ Open DCCB. open the DCCB1, after 100ms, and open DCB2.
★ Open PB. If the current detected by sensor DCCT after 200ms is
not zero, the pyrobreaker PB will open.
★ Fuse melt, and Energy is dissipated in R . The current
flowing through the magnet then follows the circuit through CU3, R and
L, and the majority of the energy is deposited in R.
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DC Current Breaker
Rated voltage
1.5kV
Rated current
15kA
Max. breaking current
50kA
Max. breaking voltage
3.0kV
Closing time
110ms
Switching time
30ms
Operation numbers
104 times
Weight
210kg
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Current and voltage curve for DCCB test
B– breaker current ; C– arc voltage
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Backup Breaker--PB
Rated current
20kA
Max. breaking voltage 2.0kV
Max. voltage
10kV
Breaking time
100µs
weight
110kg
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Discharge Resister and Fuse
The QP in each power supply
d [i ]
will work during the quench of
[ L]
 [ R ][i ]  0
dt
any PF coil. Therefore the PF
QP system consists of 12 R-L
[i] |t 0  [i0 ]
branches that have magnetic
1
coupling, the total maximum
[i0 ][ L][i0 ]T  E max
energy Emax stored in all coils
2
should be dissipated in these
2
i
 j dt  Am (j  1, 2, ......,12) resistor R of each QP. In R
design it is necessary to consider
i j R j  um
(j  1 , 2, ........, 12 ) whole energy transfer and max.
energy storage in each PF coil
and different operation time
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Fuse
Current
400A
1000A
Melting
time
Not melt
850s
2000A
80s
5000A
0.8s
15000A
0.01s
Pay attention:
★ at high current, melt rapidly
★ at low current, melt longer
★ shunt current from parallel
switch
★ Suitable fuse parameter
match with SC magnet heat
condition.
★ two diodes in opposite parallel
are in series with fuse
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Coil Current in Quench protection
5s /elongation
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Coil energy in Quench protection
5s /elongation
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I2t in Quench protection
5s /elongation
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quench signal
Control Unit for QP
software controller
hardware controller
QP controllers consist of
two parts: one is
hardware controller
realized by electronic
circuit and relay; others
is software controller
realized by realtime
operation system and
industrial computers.
CU1 or CU2 inveres
delay20ms
trigger CU3
DCCB1 switch off
HVBC switch off
delay80ms
delay 80ms
delay 100ms
Up commands …
DCCB2 switch off
delay 200ms
PB switch off
&
DCCT>0
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Parts of PF power supply equipment (7)
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The end
Thanks