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Design of the central control system for the Large Helical Device (LHD)
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH
Nuclear Instruments and Methods in Physics Research A 352 (1994) 43-46 North-Holland
SechonA
Design of the central control system for the Large Helical Device (LHD) K. Yamazaki *, H. Kaneko, S. Yamaguchi, K.Y. Watanabe, Y. Taniguchi, O. Motojima, LHD group National Institute for Fusion Science, Chikusa-ku Nagoya 464-01, Japan
The world largest superconducting fusion machine LHD (Large Helical Device) is under construction in Japan, aiming at steady-state operations. Its basic control system consists of UNIX computers, F D D l / E t h e r n e t LANs, VME multiprocessors and VxWorks real-time OS. For flexible and reliable operations of the LHD machine a cooperative distributed system with more than 30 experimental equipments is controlled by the central computer and the main timing system, and is supervised by the main protective interlock system. Intelligent control systems, such as applications of fuzzy logic and neural networks, are planed to be adopted for flexible feedback controls of plasma configurations in addition to the classical PID control scheme. Design studies of the control system and related R&D programs with coil-plasma simulation systems are now being performed. The construction of the LHD control building on a new site will begin in 1995 after finishing the construction of the LHD Experimental Building, and the hardware construction of the LHD central control equipment will be started in 1996. The first plasma production by means of this control system is expected in 1997.
1. Introduction F u s i o n energy is an u l t i m a t e a n d infinite source of energy for h u m a n s a n d is expected to be c r e a t e d in a controlled m a n n e r d u r i n g the next century. A m o n g several classes of fusion c o n c e p t s t h e t o k a m a k is t h e world l e a d e r of the p r e s e n t fusion research, but the field d e p e n d s on the toroidal c u r r e n t in the plasma itself, which is n o t a d e q u a t e for steady-state operations. O n the o t h e r h a n d , a helical m a g n e t i c system is c r e a t e d by the external helical coil only, in stead of the toroidal field coils a n d the p l a s m a c u r r e n t of t o k a m a k systems. T h e helical system c a n p r o d u c e steady-state a n d c u r r e n t l e s s plasmas, the merits of which will be d e m o n s t r a t e d in o u r new m a c h i n e . T h e Large Helical Device ( L H D ) [1-2] is the world's largest s u p e r c o n d u c t i n g fusion m a c h i n e , now u n d e r c o n s t r u c t i o n in Japan. T h e m a j o r d i a m e t e r of the L H D p l a s m a is 7.8 m a n d the central m a g n e t i c field is 4.0 T. T h e m a g n e t i c field energy s t o r e d in t h e coil will b e a r o u n d 1.6 GJ. U n l i k e the c o n v e n t i o n a l fusion machines o p e r a t e d at p r e s e n t , all coils of the L H D are s u p e r c o n d u c t i v e to d e m o n s t r a t e t h e steady-state operation. T h e design studies for the control system [3-4] of the L H D m a c h i n e have b e e n carried out, c o n c e n t r a t ing o n the m o d e definition of the m a c h i n e - p l a s m a operations, the a r c h i t e c t u r e of the L H D control sys* Corresponding author.
tern, the real-time intelligent control system for the plasma control and the R & D p r o g r a m s for the L H D central control system.
2. LHD system overview
2.1. Control design philosophy E x p e r i m e n t a l fusion systems are not as large in d i m e n s i o n s as accelerator systems, but fusion m a c h i n e s are characterized by the complicated and high energy density in the system. T h e r e f o r e the safety requirem e n t s are important. Moreover, a fusion m a c h i n e requires flexibility to o p e r a t e as a physics r e s e a r c h machine in o r d e r to optimize the m a g n e t i c configuration. As for the L H D machine, it is a large heavy-duty device requiring reliable a n d safe operations, a n d a physics m a c h i n e requiring flexible operations. M o r e over, the control system itself should be e x t e n d a b l e in o r d e r to i n c o r p o r a t e future modifications. Therefore, the following characteristics are required: 1) safe a n d reliable distributed processing for machine operations, 2) flexible a n d central o p e r a t i o n for experiments, and 3) s t a n d a r d i z a t i o n a n d flexible design using an o p e n system. T h e c o n c e p t u a l a n d d e t a i l e d designs of control, protective interlock a n d timing systems are u n d e r way,
0168-9002/94/$07.00 © 1994 - Elsevier Science B.V. All rights reserved SSDI 016 8 - 9 0 0 2 ( 9 4 ) 0 0 0 51 - 8
II. STATUS & SYSTEMS ARCHITECTURE
44
K. Yamazaki et al. /Nucl. Instr. and Meth. in Phys. Res A 352 (1094) 43-46 NIFSBackboneLAN (FDDI)
~ y ~ a t ~
~everaJyears ~veralmomhs L
Control System
VacuumEvacuation
f
k__ ~Experiment mode IMagnet Operation)
I
Magneticfield
/
- l0 hours ~
°:::Tr°e~':t:°~ . . . . . . . . . .
,~ 1~
nexi da> ..... / " -
~
.....
}E×perimentmodeIPlasmaOpera_t~on)J
!
~,.... ~°duc'i°nA U - T L
........
P~asmaHeating
l
" Plasn~aDiag.r~ostics. . . . . . . . . . . . . . . . . . . . . . . . - - ~ -
~ I hour pulses
i
i
i
.
i
Fig. 2. Global control architecture of LHD (Large Helical Device).
time
Fig. 1. Machine/plasma operation modes. sists of the superconducting (SC) magnet operation mode and the plasma experiment mode. These modes are defined for clarifying the personnel entrance permission, magnetic field hazard and possible radiation exposure. Besides the slow software interlock, the hardwired interlock logic should be determined independent of these modes. The SC magnet will be operated for about ten hours per day, and the number of
taking the flexible and reliable operations for LHD experiments into account. 2.2. Operation scenarios
The LHD machine operation is divided into three modes; shutdown mode, facility operation mode and experiment mode (Fig. 1), The experiment mode con-
•
?
[ s'~°'~ti°~II
leo
Computer
Diagnostic
~
Diagnostic LAN
Torus LAN
(Ethernet)
~stic Protection Interlock
Torus ProtectivefnterJ(
Control
Coil Power
-~[
)iagnostic Control
To,usMoo,to,io~ PI. . . .
~"
)iagnostic Timing
Terus Timing
, ~
_
~i/
~
[
"--~,.~_-
S u p p l . .
"-;o~,a~ '- - *[
, , .
Liq. He Relfigerat
.....
~a,ve~ox~ s ~
-~
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-
L~''"'~!
-'~,
'
__.[
Diagnostic Control
CACAO
F--
c,MAo
k--
F--WMotor Generator ]-"--
~tt
]-E-mergencyPower S. } ~
L :
S--econdaryCooling ] - ~ Timing Signalf
Protective Interlock Signal (Hardwired)
VacuumPumping
Gas Puffing Gas Purification
Inj----~"-~-Ctor Penet
Torus LAN IEthernetl
Fig. 3. System diagram of LHD control.
]
i
45
K. Yamazaki et aL /NucL Instr. and Meth. in Phys. Res A 352 (1994) 43-46
short-pulsed plasma operations with 10 s duration will be typically 50-100 shots per day. Unlike the present conventional pulsed fusion machines, the LHD is going to be operated in the steady state (i.e. more than 1 h pulse length) and requires interactive control of the machine and plasma. Electromagnetic sensors for the long-pulsed control, which is different from the control concept of present conventional fusion devices, are required.
quenched, it is necessary to wait for one second before making an emergency stop of the coil current, to avoid the plasma current induction and hard X-ray production by means of the protective gas injection or the protective rod insertion. The information about these protective actions is transferred to the experimental control computer via LHD control Ethernet-LAN.
4. Intelligent feedback control scheme 3. LHD control system and its standardization 3.1. Global control architecture
On the basis of the above-stated operation scenarios, the proposed control system is composed of the central experimental control system which deals with the plasma experiment mode, and several sub-supervisory control systems to arrange facility operation mode such as torus machine control, heating machine control, diagnostic control and electric/cooling utility control systems, as shown in Fig. 2. All sub-supervisory systems are connected by the Ethernet-LAN. The data acquisition system, having conventional CAMAC modules with our specially developed softwares and the large supercomputer system for theoretical analyses using experimental data, are connected to the experimental control computer by the interlaboratory backbone FDDI-LAN. 3.2. Design o f the central system and sub-systems
The detailed diagram of the LHD control system is shown in Fig. 3. Within the facility operation mode, almost all the equipments are operated by thier subsystem controllers. The liquid helium refrigerator, the coil current power supply, the vacuum pumping, and the wall conditioning systems are controlled from the main torus control system. Each plasma heating system such as NBI, ECH and ICRF is operated by its own control computer. On the other hand, in the experiment mode, most of the input parameters are controlled from the engineering workstation (EWS) of the central experimental control system. The timing system is important to create a flexible and reproducible plasma, and its functions are distributed among the main timing system and the torus timing system. Each equipment has its own simple and reliable interlock system and the cooperative protection is performed by a common fast interlock system with multiple hard-wired lines, in addition to the slow software computer control system. It is expecially important to arrange a comprehensive fast emergency stop during the plasma operation. For example, when the SC coil is
The feedback control for plasma current, position and cross-sectional shape will be carried out using intelligent control systems, using fuzzy logic and neural networks in addition to the standard PID algorithm. For example, fuzzy logic will be applied to the change in the control algorithm or to the fuzzification of input parameters for the control of the plasma current and position. The former application has been checked with a simulation model of the plasma current control and it was found that the fuzzy control is better for the nonlinear control response than the classical PID controller [3]. The neural network will be applied to the fine-tuning control of the plasma cross-sectional shape and is now under investigation.
5. R & D program for control system
As an R & D program for this LHD control system, a new simulation system is being made, consisting of a UNIX-EWS (Sun Sparc Station), Ethernet-LAN, VME multiprocessors (CPU 68030) with VxWorks real-time OS, simulation power supplies and a plasma-coil system (Fig. 4). For quick and accurate control response, a digital signal processor (DSP) board will be installed with the fuzzy logic plasma control algorithm [3] in addition to a PID controller for the demonstration of the plasma control and display. This R & D program will help the design and construction of LHD central control facilities.
Ethemet-LAN | [ Q I~ / VME System
I [3
Power Supply Plasma-CoilSystem bys~em .-~
Fig. 4. R&D system for LHD control.
II. STATUS & SYSTEMS ARCHITECTURE
46
K~ Yamazaki et al. /Nucl. Instr. and Meth. in Phys, Res A 352 (1994) 43-46
6. Construction schedule of control system and building The LHD machine is now under construction, and the detailed design of its central control system will be made in the period 1993-1995. Its central computer system will be installed in the LHD control building. The initial test operation of the LHD magnet system will induce a strong leakage magnetic field in the adjacent building which could make the computer inoperative. To avoid this, the L H D Control Building is planned to be located ~ 100 m away from the L H D machine. The expected magnetic field is 1 G in the initial coil test phase and less than 0.1 G in the normal operation phase. The construction of this control building on the new site will begin in 1995 after finishing the
construction of the LHD experimental building, and the hardware construction of the LHD central control equipments will start in 1996. The first plasma production by means of this control system is expected in 1997.
References [1] A. liyoshi et al., Fusion Technol. 17 (1990) 169. [2] O. Motojima et al., Fusion Eng. and Design 20 (1993) 3. [3] K. Yamazaki et al., Proc. Int. Conf. on Accelerator and Large Experimental Physics Control Systems, eds. C.O. Pak, S. Kurokawa and T. Katoh, KEK proceedings 92-15, p. 228. [4] H. Kaneko et al., Fusion Eng. and Design 20 (1993) 121.
Nuclear Instruments and Methods in Physics Research A 352 (1994) 43-46 North-Holland
SechonA
Design of the central control system for the Large Helical Device (LHD) K. Yamazaki *, H. Kaneko, S. Yamaguchi, K.Y. Watanabe, Y. Taniguchi, O. Motojima, LHD group National Institute for Fusion Science, Chikusa-ku Nagoya 464-01, Japan
The world largest superconducting fusion machine LHD (Large Helical Device) is under construction in Japan, aiming at steady-state operations. Its basic control system consists of UNIX computers, F D D l / E t h e r n e t LANs, VME multiprocessors and VxWorks real-time OS. For flexible and reliable operations of the LHD machine a cooperative distributed system with more than 30 experimental equipments is controlled by the central computer and the main timing system, and is supervised by the main protective interlock system. Intelligent control systems, such as applications of fuzzy logic and neural networks, are planed to be adopted for flexible feedback controls of plasma configurations in addition to the classical PID control scheme. Design studies of the control system and related R&D programs with coil-plasma simulation systems are now being performed. The construction of the LHD control building on a new site will begin in 1995 after finishing the construction of the LHD Experimental Building, and the hardware construction of the LHD central control equipment will be started in 1996. The first plasma production by means of this control system is expected in 1997.
1. Introduction F u s i o n energy is an u l t i m a t e a n d infinite source of energy for h u m a n s a n d is expected to be c r e a t e d in a controlled m a n n e r d u r i n g the next century. A m o n g several classes of fusion c o n c e p t s t h e t o k a m a k is t h e world l e a d e r of the p r e s e n t fusion research, but the field d e p e n d s on the toroidal c u r r e n t in the plasma itself, which is n o t a d e q u a t e for steady-state operations. O n the o t h e r h a n d , a helical m a g n e t i c system is c r e a t e d by the external helical coil only, in stead of the toroidal field coils a n d the p l a s m a c u r r e n t of t o k a m a k systems. T h e helical system c a n p r o d u c e steady-state a n d c u r r e n t l e s s plasmas, the merits of which will be d e m o n s t r a t e d in o u r new m a c h i n e . T h e Large Helical Device ( L H D ) [1-2] is the world's largest s u p e r c o n d u c t i n g fusion m a c h i n e , now u n d e r c o n s t r u c t i o n in Japan. T h e m a j o r d i a m e t e r of the L H D p l a s m a is 7.8 m a n d the central m a g n e t i c field is 4.0 T. T h e m a g n e t i c field energy s t o r e d in t h e coil will b e a r o u n d 1.6 GJ. U n l i k e the c o n v e n t i o n a l fusion machines o p e r a t e d at p r e s e n t , all coils of the L H D are s u p e r c o n d u c t i v e to d e m o n s t r a t e t h e steady-state operation. T h e design studies for the control system [3-4] of the L H D m a c h i n e have b e e n carried out, c o n c e n t r a t ing o n the m o d e definition of the m a c h i n e - p l a s m a operations, the a r c h i t e c t u r e of the L H D control sys* Corresponding author.
tern, the real-time intelligent control system for the plasma control and the R & D p r o g r a m s for the L H D central control system.
2. LHD system overview
2.1. Control design philosophy E x p e r i m e n t a l fusion systems are not as large in d i m e n s i o n s as accelerator systems, but fusion m a c h i n e s are characterized by the complicated and high energy density in the system. T h e r e f o r e the safety requirem e n t s are important. Moreover, a fusion m a c h i n e requires flexibility to o p e r a t e as a physics r e s e a r c h machine in o r d e r to optimize the m a g n e t i c configuration. As for the L H D machine, it is a large heavy-duty device requiring reliable a n d safe operations, a n d a physics m a c h i n e requiring flexible operations. M o r e over, the control system itself should be e x t e n d a b l e in o r d e r to i n c o r p o r a t e future modifications. Therefore, the following characteristics are required: 1) safe a n d reliable distributed processing for machine operations, 2) flexible a n d central o p e r a t i o n for experiments, and 3) s t a n d a r d i z a t i o n a n d flexible design using an o p e n system. T h e c o n c e p t u a l a n d d e t a i l e d designs of control, protective interlock a n d timing systems are u n d e r way,
0168-9002/94/$07.00 © 1994 - Elsevier Science B.V. All rights reserved SSDI 016 8 - 9 0 0 2 ( 9 4 ) 0 0 0 51 - 8
II. STATUS & SYSTEMS ARCHITECTURE
44
K. Yamazaki et al. /Nucl. Instr. and Meth. in Phys. Res A 352 (1094) 43-46 NIFSBackboneLAN (FDDI)
~ y ~ a t ~
~everaJyears ~veralmomhs L
Control System
VacuumEvacuation
f
k__ ~Experiment mode IMagnet Operation)
I
Magneticfield
/
- l0 hours ~
°:::Tr°e~':t:°~ . . . . . . . . . .
,~ 1~
nexi da> ..... / " -
~
.....
}E×perimentmodeIPlasmaOpera_t~on)J
!
~,.... ~°duc'i°nA U - T L
........
P~asmaHeating
l
" Plasn~aDiag.r~ostics. . . . . . . . . . . . . . . . . . . . . . . . - - ~ -
~ I hour pulses
i
i
i
.
i
Fig. 2. Global control architecture of LHD (Large Helical Device).
time
Fig. 1. Machine/plasma operation modes. sists of the superconducting (SC) magnet operation mode and the plasma experiment mode. These modes are defined for clarifying the personnel entrance permission, magnetic field hazard and possible radiation exposure. Besides the slow software interlock, the hardwired interlock logic should be determined independent of these modes. The SC magnet will be operated for about ten hours per day, and the number of
taking the flexible and reliable operations for LHD experiments into account. 2.2. Operation scenarios
The LHD machine operation is divided into three modes; shutdown mode, facility operation mode and experiment mode (Fig. 1), The experiment mode con-
•
?
[ s'~°'~ti°~II
leo
Computer
Diagnostic
~
Diagnostic LAN
Torus LAN
(Ethernet)
~stic Protection Interlock
Torus ProtectivefnterJ(
Control
Coil Power
-~[
)iagnostic Control
To,usMoo,to,io~ PI. . . .
~"
)iagnostic Timing
Terus Timing
, ~
_
~i/
~
[
"--~,.~_-
S u p p l . .
"-;o~,a~ '- - *[
, , .
Liq. He Relfigerat
.....
~a,ve~ox~ s ~
-~
Coo,,ng
-
L~''"'~!
-'~,
'
__.[
Diagnostic Control
CACAO
F--
c,MAo
k--
F--WMotor Generator ]-"--
~tt
]-E-mergencyPower S. } ~
L :
S--econdaryCooling ] - ~ Timing Signalf
Protective Interlock Signal (Hardwired)
VacuumPumping
Gas Puffing Gas Purification
Inj----~"-~-Ctor Penet
Torus LAN IEthernetl
Fig. 3. System diagram of LHD control.
]
i
45
K. Yamazaki et aL /NucL Instr. and Meth. in Phys. Res A 352 (1994) 43-46
short-pulsed plasma operations with 10 s duration will be typically 50-100 shots per day. Unlike the present conventional pulsed fusion machines, the LHD is going to be operated in the steady state (i.e. more than 1 h pulse length) and requires interactive control of the machine and plasma. Electromagnetic sensors for the long-pulsed control, which is different from the control concept of present conventional fusion devices, are required.
quenched, it is necessary to wait for one second before making an emergency stop of the coil current, to avoid the plasma current induction and hard X-ray production by means of the protective gas injection or the protective rod insertion. The information about these protective actions is transferred to the experimental control computer via LHD control Ethernet-LAN.
4. Intelligent feedback control scheme 3. LHD control system and its standardization 3.1. Global control architecture
On the basis of the above-stated operation scenarios, the proposed control system is composed of the central experimental control system which deals with the plasma experiment mode, and several sub-supervisory control systems to arrange facility operation mode such as torus machine control, heating machine control, diagnostic control and electric/cooling utility control systems, as shown in Fig. 2. All sub-supervisory systems are connected by the Ethernet-LAN. The data acquisition system, having conventional CAMAC modules with our specially developed softwares and the large supercomputer system for theoretical analyses using experimental data, are connected to the experimental control computer by the interlaboratory backbone FDDI-LAN. 3.2. Design o f the central system and sub-systems
The detailed diagram of the LHD control system is shown in Fig. 3. Within the facility operation mode, almost all the equipments are operated by thier subsystem controllers. The liquid helium refrigerator, the coil current power supply, the vacuum pumping, and the wall conditioning systems are controlled from the main torus control system. Each plasma heating system such as NBI, ECH and ICRF is operated by its own control computer. On the other hand, in the experiment mode, most of the input parameters are controlled from the engineering workstation (EWS) of the central experimental control system. The timing system is important to create a flexible and reproducible plasma, and its functions are distributed among the main timing system and the torus timing system. Each equipment has its own simple and reliable interlock system and the cooperative protection is performed by a common fast interlock system with multiple hard-wired lines, in addition to the slow software computer control system. It is expecially important to arrange a comprehensive fast emergency stop during the plasma operation. For example, when the SC coil is
The feedback control for plasma current, position and cross-sectional shape will be carried out using intelligent control systems, using fuzzy logic and neural networks in addition to the standard PID algorithm. For example, fuzzy logic will be applied to the change in the control algorithm or to the fuzzification of input parameters for the control of the plasma current and position. The former application has been checked with a simulation model of the plasma current control and it was found that the fuzzy control is better for the nonlinear control response than the classical PID controller [3]. The neural network will be applied to the fine-tuning control of the plasma cross-sectional shape and is now under investigation.
5. R & D program for control system
As an R & D program for this LHD control system, a new simulation system is being made, consisting of a UNIX-EWS (Sun Sparc Station), Ethernet-LAN, VME multiprocessors (CPU 68030) with VxWorks real-time OS, simulation power supplies and a plasma-coil system (Fig. 4). For quick and accurate control response, a digital signal processor (DSP) board will be installed with the fuzzy logic plasma control algorithm [3] in addition to a PID controller for the demonstration of the plasma control and display. This R & D program will help the design and construction of LHD central control facilities.
Ethemet-LAN | [ Q I~ / VME System
I [3
Power Supply Plasma-CoilSystem bys~em .-~
Fig. 4. R&D system for LHD control.
II. STATUS & SYSTEMS ARCHITECTURE
46
K~ Yamazaki et al. /Nucl. Instr. and Meth. in Phys, Res A 352 (1994) 43-46
6. Construction schedule of control system and building The LHD machine is now under construction, and the detailed design of its central control system will be made in the period 1993-1995. Its central computer system will be installed in the LHD control building. The initial test operation of the LHD magnet system will induce a strong leakage magnetic field in the adjacent building which could make the computer inoperative. To avoid this, the L H D Control Building is planned to be located ~ 100 m away from the L H D machine. The expected magnetic field is 1 G in the initial coil test phase and less than 0.1 G in the normal operation phase. The construction of this control building on the new site will begin in 1995 after finishing the
construction of the LHD experimental building, and the hardware construction of the LHD central control equipments will start in 1996. The first plasma production by means of this control system is expected in 1997.
References [1] A. liyoshi et al., Fusion Technol. 17 (1990) 169. [2] O. Motojima et al., Fusion Eng. and Design 20 (1993) 3. [3] K. Yamazaki et al., Proc. Int. Conf. on Accelerator and Large Experimental Physics Control Systems, eds. C.O. Pak, S. Kurokawa and T. Katoh, KEK proceedings 92-15, p. 228. [4] H. Kaneko et al., Fusion Eng. and Design 20 (1993) 121.