lq quench protection – g. ambrosio 1 lq ds video mtg – may. 23, 2007 bnl - fnal - lbnl - slac...
TRANSCRIPT
BNL - FNAL - LBNL - SLAC
Long Quadrupole Quench Protection Giorgio Ambrosio
LQ DS Video-Meeting May. 23, 2007
OUTLINE:
• LQ Quench protection• Spikes recorded during TQS01c test• Comparison with real quench signals• Plan
LQ Quench Protection – G. Ambrosio 2LQ DS video Mtg – May. 23, 2007
TQ/LQ conductor parameters
Parameter Unit Value
N of strands - 27
Strand diameter mm 0.700
Bare width mm 10.050
Bare inner edge thickness mm 1.172
Bare outer edge thickness mm 1.348
Keystoning angle deg. 1.000
Radial insulation thickness mm 0.125
Azimuthal insulation thickness mm 0.125
Copper to non-copper ratio - 0.89
Copper RRR - 100
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Magnet parametersParameter Unit LQ
N of layers - 2
N of turns - 136
Coil area (Cu + nonCu) cm2 29.33
Length m 3.6
Jc(12 T, 4.2 K) = 2400 A/mm2
4.2 K temperature
Quench gradient T/m 223.49
Quench current kA 13.47
Peak field in the coil at quench T 11.59
Inductance at quench mH/m 4.1
Stored energy at quench kJ/m 372
1.9 K temperature
Quench gradient T/m 240.57
Quench current kA 14.57
Peak field in the coil at quench T 12.48
Stored energy at quench kJ/m 435
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LQ Quench Protection
• QuenchPro Input– Magnet parameters: TQC01 x 3.6 m coils
• Conductor: TQ cable (Jc 2400 A/mm2)
• Total energy: 1.3 MJ @ 4.4K
• Code and input validation– Geometry, inductance, mat. prop (QLASA/Opera/ROXIE/TQC01): Done
– Effect of changes to quench propagation routine: Very small
• Comparison with TQs data – TQ tests set MIITs limit: in progress
• Quench protection parameters (aggressive)– Detection time: 5 - 10 ms based on TQs
– Heater delay time: 10 - 15 ms based on TQs
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Protection heater delay + detection time
0
10
20
30
40
50
60
70
80
90
0 2000 4000 6000 8000 10000
Current (A)
Tim
e (m
s)
200 V
300 V
400 V
TQs Heater Delay & Detection Time
• Heater delay time: t ~ 10 ms close to quench plateau; t < 15 ms at I = 62% Issl
• Detection time: 3 - 11 ms during TQS01c training– Flux jumps up to 600 mV with MJR cable
TQC01
TQC01 protection heater studies by using spot heaters to initiate the quench.
mse
c
TQS01c
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MIITs Limit
• During TQC01 test, one QI vs. T measurementI: 5000 A , QI: 9.05 MIITs, Peak Temp: 340 K
• Impact on quench performance of high-MIITs quenches (TQS01c)
• + 4% after 8 MIITs• - 2.9% after 8.1 MIITs• - 7.4% after 8.7 MIITs• - 18.4 after 9.5 MIITs• Small bumps at 7.5 MIITs
LQ Quench Protection – G. Ambrosio 7LQ DS video Mtg – May. 23, 2007
100% coverage 75% coverage 50% coverage
4.4 K
Hot Spot
7.6MIITs
Heaters
4.6MIITs
7.9MIITs
4.9MIITs
8.3MIITs
5.3MIITs
Turn-turn
55 VGround
446 V 65 V 459 V 84 V 536 V
1.9 K
8.4MIITs
4.9MIITs
8.7MIITs
5.2MIITs
9.2MIITs
5.7MIITs
72 V 489 V 85 V 520 V 109 V 615 V
MIITs and Voltage at quench currentDump = 60 m
Detection time = 5 msHeater delay time = 12 ms
High MIITs at 1.9K
Voltages OK
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How to get margin for safe LQ test?
– 100% heater coverage with 4 independent circuits per coil • to be ~safe in case of failure (easier heater manufacturing, see LR)
– Shorter detection time and/or heater delay time?• Heater design, and QP system upgrade
– Larger dump resistance?• Hard at 1.9K: with 60 mohm we have ~ 1 kV at the leads• Possible at 4.5 K: could go up to 75 mohm
– Lower RRR in order to have shorter detection time?• …risky…
– Improve/upgrade VMTF Quench Detection System: • Low threshold * small time: in order to avoid trips induced by spikes• Capability of changing QDS threshold easily during tests
Y
Y
?
N
Y
LQ quench protection with TQ-like coils is
challenging but doable at 4.5K
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Needs for LQ QP
• Four independent circuits for protection heaters• Change dump resistance at 1.9K?• Design LQ protection heaters• Easily changeable detection threshold• Develop smart quench detection to avoid spikes
with low threshold?– Time
– Voltage slope
– Spike recognition
– Current depending threshold
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Last trip by flux jump
Threshold was 600 mV
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Half coil
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• 4 coils
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Quad 2 = Coil 8 segments
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VSDS
Quench
NO quench
NO quench
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Quenches
Quench 51 - I = 9600 A, T = 4.5 K, Rate = 20 A/s
Time for decision should be less than 2 ms
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New QDS … in progress
FPGA-based system: • It is firmware running in a PXI board, and it does not depend on an
operating system such as VxWorks, Linux, or Windows. • Note that you already depend on this approach for VMTF quench
detection and protection: in the current VMTF system, the Quench Logic Module (QLM) logic is programmed in firmware, and you depend on this module to perform properly to protect a magnet.
• This can really simplify the complexity of the system, as we have seen with the Stand 3 example. It can also make it easier to implement the type of adaptive logic we discussed during the meeting.
• Of course we need to discuss what level of redundancy or analog backups we need for risk mitigation.
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Appendix
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Quench Pro I
• Analytical code
• Adiabatic approximation
• Temperature computed from Quench Integral– Field is constant (average); different values for hot spot and bulk
– Epoxy included in QI
– Strand non_Cu = 76% Nb3Sn, 33% bronze (by Arup)
• Longitudinal propagation by QP velocity
• Quench starts under heaters – after detection time + heater delay time
• Temperature is uniform (given by QI) in normal zone of each cable – Different between Hot-spot and bulk
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Quench Pro II
• Current decay– Magnet can be switched to a dump resistance (after
detection) or leads are short-circuited – Current decay is computed based on the instantaneous
time constant (computed from the growing resistance and the inductance)
– Inductance is computed based on position of each turn (inductance matrix)
• Voltages– Computed based on current, resistance, dI/dt,
inductance matrix, (at dI/dt max)– Turn to ground– Turn to turn
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Sensitivity to Quench Prop. simulation
• New quench propagation routine in QuenchPro to better fit LQ magnet features
Very small effect!
Temperature vs. MIITs tuned on TQC01Dump = 60 m
Detection time = 8 msHeater delay time = 15 ms
100% coverage 75% coverage 50% coverage
1.9 K
412 KHot spot
108 KHeaters
449 K 121 K 504 K 143 K
412 K 108 K 441 K 118 K 490 K 138 K
OLDroutine
NEWroutine