The H-1NF Heliac and Engineering Subsystems Tolerance Band DC-DC Convertor PWM inherently voltage...
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The H-1NF Heliac and Engineering Subsystems Tolerance Band DC-DC Convertor • PWM inherently voltage source - V out = Vin •Tolerance band – fast responding current source - high performance even in open loop, also removes 1 pole from FB loop – inherently variable frequency conflicts with desire for phase interleaving in multiphase systems – inherent GTO protection (I<3kA) Upper limit Lower limit GTO Current M inim ize Pow er Line D isturbance H -1N F P ow er S ystem C om pensation p erm an e nt h arm onic filte r (1 1kV , 2.5 M VA r) 1 second critica l a ccu ra cy tim e w in d ow ANU ACTEW supp ly drop H -1 cu rren t ANU ACTEW supp ly drop H -1 com p en satio n total -4% droop DC cu rren t A C lin e d ro o p co rrected V I • Harm onics – 24 phase diode bridge, full conduction angle • D isturbances – ram p load sm oothly by dum ping pow er • D roop – Sw itched capacitor “overcom pensation” H -1N F 11k V 3 sw itch g e ar 11kV :: 800V tran sfo rm e r 24 pulse re ctifie r + + 10 ea.1M W D C -D C co n v e rto r S V C sw itch ed pow er fa cto r ad ju stm e n t 1-4M V A r,800V H -1 N F 10M W M agnet P ow e r S up p ly S ystem + H-1 800V D C 14,000A perm anent h arm o n ic filte r (11kV ,2.5M VA r) 2kH z P WM 1 second critica lac cu ra cy tim e w indow Feedback Control Constant-power power converter negative resistance I in =P/V in I/ V ~ -1/V 2 input LC instability (45Hz) Output filter capacitor and magnet second resonance (20Hz) 400ms time constant Feedback control is like PID , but voltage derivative (proportional/integral/derivative) Implementation with real time 68000 P, 600 s per cycle programmed in “Hawk ” C Mean value filters for quick response (top hat) Current Ramp Scans Plasma Achieved: •three confinement modes in one pulse, by varying magnetic field •Can also vary configuration pulse to pulse or during a pulse 20 A m p ram p on a 4000 A m p pulse R ipple Causes“shim m er” in configuration D B/dt EM F unw anted plasm a current Possible reconnectionsand heating atsurface A chieved: • Ripple current<< 1A m p • D I/dt(0-30H z)< 10A /s (highly suppressed zero) 12MW Pulsed Power Supply for the H-1NF Magnet DC-DC Convertor/Regulator: ABB Aust. /Technocon AG 24 Pulse Rectifier: Cegelec Australia Transformers/Reactors: TMC Australia Switchgear: Holec Australia and A-Force Switchboards, Sydney Consultant Engineers: Walshe & Associates, Sydney • 1-14kA , 800V , <1A m p precision:m ain m agnet • 1-14kA , 100V , <1A m p precision:controlm agnet • Ripple and D I/dtsm allto avoid “shim m er” and induced currents(plasm a conductivity ~copper) • M inim ize line disturbance (14M V A load) • Protectheliac w indings (100kA /50uscrow bar) Specifications H-1 was the first large scale “heliac”, a particular type of helical axis stellarator which was conceived in 1969 in mathematical form as a plasma configuration with strong inherent magnetic well for stability at high plasma pressure. A realizable form was invented at Princeton in 1982, and the first experimental device, “SHEILA” was built and operated at the ANU in 1985. The helical axis, strong plasma twist, “bean shaped” plasma and simple circular coils are features of this configuration. H-1 was constructed entirely (apart from the vacuum shell) by the Plasma Research Laboratory and RSPhysSE workshop staff, to extremely high accuracy (~1mm), in spite of the complicated interlinking shape and the large forces on the conductors (~ 5 Tonnes per coil). H-1 employs one small helical winding, which greatly increases the range of plasma shapes (“flexible heliac”). Other heliacs have been built in Japan and Spain, and a next generation machine, a large superconducting “helias” is under construction in Germany, which although quite different, has the familiar bean shape in some cross sections. Helic al plasm a (Argo n) Helical conductor control winding 5 tonne support structure Rotating 55 view Doppler tomography system Rotating 64 wire electron beam tomography system Diamagnetic energy monitor Pentagonal central support column 14000Amp bus conductor and cooling H-1 is controlled by a PLC system (Programmable Logic Controller). Each of 4 PLCs is a small, real-time computer executing 20-40 complete monitoring cycles every second. H-1 Control System Main Control Screen (Overview) Subsystems are summarised in each box, red and green indicating faults and normal operation. Each sub system has a deatiled screen such as that below. Cooling Sub system The magnetic field coils dissipate up to 12MW of power, which must be removed as heat. The high purity H-1 cooling water transfers this heat through a heat exchanger to an evaporative cooling tower. Each coil’s temperature is monitored closely (lower left) RF Heating Systems Microwave Source: (Kyoto-NIFS-ANU collab.) 28 GHz gyrotron 230 kW ~ 40ms H-1 may be heated at both the electron cyclotron resonance (ECH) (microwave ~28GHz)and lower radio frequencies near the ion cyclotron resonance(6-26MHz, helicon and ICH). Several hundred kW are available. Ion Range RF source (ex Radio Australi • 6-26 MHz, 250 kW • Refurbished by British Aerospace • New coax from NIFS • Use for helicon, ICRF heating • 6x30kW AWA transmitters for plasma production, and phased excitation “fish-eye” view of corrugated waveguide to H-1 on left. (H.Punzmann) by Ding-fa Zhou Photos: Tim Wetherill
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Transcript of The H-1NF Heliac and Engineering Subsystems Tolerance Band DC-DC Convertor PWM inherently voltage...
The H-1NF Heliac and Engineering Subsystems
Tolerance Band DC-DC Convertor• PWM inherently voltage source - V out =Vin
• Tolerance band– fast responding current source - high performance
even in open loop, also removes 1 pole from FB loop
– inherently variable frequency conflicts with desire forphase interleaving in multiphase systems
– inherent GTO protection (I<3kA)Upper limit
Lower limit
GTO Current
Minimize PowerLine Disturbance
H-1NF Power System Compensation
permanent harmonic filte r (11kV, 2.5MVAr)
1 second
critical accuracytime window
ANU
ACTEW
supp ly drop
H-1curr ent
ANU
ACTEW
supp ly drop
H-1
compensation
t otal
-4% droop
DC curr ent
AC line droop corr ect edV I
• Harmonics– 24 phase diode bridge, full
conduction angle
• Disturbances– ramp load smoothly by
dumping power
• Droop– Switched capacitor
“overcompensation”
H-1NF
11kV 3
sw itchgear
11kV :: 800Vtransformer
24 pulse rectifier
+ +
10 ea. 1MW DC-DC convertor
SVC switchedpower factor adjustment
1-4MV Ar, 800V
H-1NF 10MW Magnet Power Supply System
+H-1 800VDC 14,000A
permanentharmonic filter (11kV, 2.5MVAr)
2kHz PWM
1 second
crit ical accuracytime window
Feedback ControlConstant-power power converter negative resistance
Iin=P/V in I/ V ~ -1/V 2 input LC instability (45Hz)
Output filter capacitor and magnet second resonance (20Hz)400ms time constant
Feedback control is like PID , but voltage derivative (proportional/integral/derivative)
Implementation with real time 68000 P, 600 s per cycleprogrammed in “Hawk ” C
Mean value filters for quick response (top hat)
Current Ramp ScansPlasma
Achieved:
•three confinement modes inone pulse, by varying magneticfield
•Can also vary configurationpulse to pulse or during a pulse
20 Amp ramp on a 4000 Amp pulse
Ripple
Causes “shimmer” inconfiguration
DB/dt EMF unwanted plasma current
Possible reconnections andheating at surface
Achieved:
• Ripple current << 1Amp
• DI/dt (0-30Hz) < 10A/s(highly suppressed zero)
12MW Pulsed Power Supply for the H-1NF Magnet
DC-DC Convertor/Regulator: ABB Aust. /Technocon AG24 Pulse Rectifier: Cegelec Australia
Transformers/Reactors: TMC AustraliaSwitchgear: Holec Australia and A-Force Switchboards, Sydney
Consultant Engineers: Walshe & Associates, Sydney
• 1-14kA, 800V, <1Amp precision: main magnet
• 1-14kA, 100V, <1Amp precision: control magnet
• Ripple and DI/dt small to avoid “shimmer” andinduced currents (plasma conductivity ~copper)
• Minimize line disturbance (14MVA load)
• Protect heliac windings (100kA/50us crowbar)
Specifications
H-1 was the first large scale “heliac”, a particular type of helical axis stellarator which was conceived in 1969 in mathematical form as a plasma configuration with strong inherent magnetic well for stability at high plasma pressure. A realizable form was invented at Princeton in 1982, and the first experimental device, “SHEILA” was built and operated at the ANU in 1985. The helical axis, strong plasma twist, “bean shaped” plasma and simple circular coils are features of this configuration. H-1 was constructed entirely (apart from the vacuum shell) by the Plasma Research Laboratory and RSPhysSE workshop staff, to extremely high accuracy (~1mm), in spite of the complicated interlinking shape and the large forces on the conductors (~ 5 Tonnes per coil). H-1 employs one small helical winding, which greatly increases the range of plasma shapes (“flexible heliac”).
Other heliacs have been built in Japan and Spain, and a next generation machine, a large superconducting “helias” is under construction in Germany, which although quite different, has the familiar bean shape in some cross sections.
Helical plasma
(Argon)
Helical conductor control winding
5 tonne support structure
Rotating 55 view Doppler tomography systemRotating 64 wire electron
beam tomography system
Diamagnetic energy monitor
Pentagonal central support column
14000Amp bus conductor and cooling
H-1 is controlled by a PLC system (Programmable Logic Controller). Each of 4 PLCs is a small, real-time computer executing 20-40 complete monitoring cycles every second.
H-1 Control System
Main Control Screen (Overview)
Subsystems are summarised in each box, red and green indicating faults and normal operation. Each sub system has a deatiled screen such as that below.
Cooling Sub system
The magnetic field coils dissipate up to 12MW of power, which must be removed as heat. The high purity H-1 cooling water transfers this heat
through a heat exchanger to an evaporative cooling tower.
Each coil’s temperature is monitored closely (lower left)
RF Heating Systems
Microwave Source:
(Kyoto-NIFS-ANU collab.)
28 GHz gyrotron
230 kW ~ 40ms
H-1 may be heated at both the electron cyclotron resonance (ECH) (microwave ~28GHz)and lower radio frequencies near the ion cyclotron resonance(6-26MHz, helicon and ICH). Several hundred kW are available.
Ion Range RF source (ex Radio Australia)
• 6-26 MHz, 250 kW• Refurbished by British Aerospace• New coax from NIFS• Use for helicon, ICRF heating• 6x30kW AWA transmitters for plasma production, and phasedexcitation
“fish-eye” view of corrugated waveguide to H-1 on left. (H.Punzmann)
by Ding-fa Zhou
Photos: Tim Wetherill
