Hahn, Sang-Hee
(National Fusion Research Institute (NFRI))
,
Kim, K.H.
(National Fusion Research Institute (NFRI))
,
Choi, J.H.
(National Fusion Research Institute (NFRI))
,
Ahn, H.S.
(POSCON Cooperation R&D Center, 101 Korea Tech. Complex Bldg., Korea Univ.)
,
Lee, D.K.
(National Fusion Research Institute (NFRI))
,
Park, K.R.
(National Fusion Research Institute (NFRI))
,
Eidietis, N.W.
(General Atomics)
,
Leuer, J.A.
(General Atomics)
,
Walker, M.L.
(General Atomics)
,
Yang, H.L.
(National Fusion Research Institute (NFRI))
,
Kim, W.C.
(National Fusion Research Institute (NFRI))
,
Oh, Y.K.
(National Fusion Research Institute (NFRI))
As a part of the plasma control system (PCS) for the first plasma campaign of KSTAR, seven sets of fast feedback control loop for the superconducting poloidal field magnet power supply (PF MPS) have been implemented. A special real-time digital communication interface has been developed for the simu...
As a part of the plasma control system (PCS) for the first plasma campaign of KSTAR, seven sets of fast feedback control loop for the superconducting poloidal field magnet power supply (PF MPS) have been implemented. A special real-time digital communication interface has been developed for the simultaneous exchanges of the current/voltage data from the 7 sets of 12-thyristor power supplies in a 200 microsecond control cycle. Preliminary power supply tests have been performed before actual cooldown of the device. A $29mH/50m{\Omega}$ solenoid dummy has been fabricated for a series of single power supply tests. Connectivity and response speed of the plasma control system have been verified. By changing hardware cabling, this load was also used to estimate mutual inductance coupling effects of two geometrically adjacent solenoid coils on each power supply. After the cooldown was complete, each pair of the up/down symmetric PF coils has been serially connected and tested as part of the device commissioning process. Bipolar operation and longer pulse attempts have been investigated. The responses of the coils and power supplies corresponding to the plasma magnetic controls in plasma discharges are also analyzed for the future upgrades.
As a part of the plasma control system (PCS) for the first plasma campaign of KSTAR, seven sets of fast feedback control loop for the superconducting poloidal field magnet power supply (PF MPS) have been implemented. A special real-time digital communication interface has been developed for the simultaneous exchanges of the current/voltage data from the 7 sets of 12-thyristor power supplies in a 200 microsecond control cycle. Preliminary power supply tests have been performed before actual cooldown of the device. A $29mH/50m{\Omega}$ solenoid dummy has been fabricated for a series of single power supply tests. Connectivity and response speed of the plasma control system have been verified. By changing hardware cabling, this load was also used to estimate mutual inductance coupling effects of two geometrically adjacent solenoid coils on each power supply. After the cooldown was complete, each pair of the up/down symmetric PF coils has been serially connected and tested as part of the device commissioning process. Bipolar operation and longer pulse attempts have been investigated. The responses of the coils and power supplies corresponding to the plasma magnetic controls in plasma discharges are also analyzed for the future upgrades.
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문제 정의
In this paper we will describe how the controls of the power supply system have been verified and how the controls have been applied to the real superconducting coils and the plasma control during the first commissioning period.
가설 설정
(a) Comparison of the dumrny load (dash dot) and SC PF1 (solid) when the IPT-type zero-crossing is performed at -2 kA/s. (b) Behaviors of the PF7 voltage are compared for different ramp rates: -2 kA/s (solid), -3 kA/s (dash dot) and ~4 kA/s (dash).
4. (a) Mutual inductance effects are shown when the slew rates of two strongly-coupled solenoids are different, (b) For a zero-crossing situation, the mutual inductance effect is in the form of the induced voltage to the dead circuit.
3. (a) High-inductance dummy load used to the pre-commissioning of the PCS and the PF MPS controls, (b) Test result of coil current feedback control with PF1 + dummy load 29 mH/ 50 mQ + 250 mQ BRIS. In each shot the slew rate was adjusted by pre-programmed additional PS voltage during the 50 ms blip.
As shown in Fig. 6(b), bigger ramp rate before the zero-crossing scheme starts makes the dead time shorter. It should be apparent because the sooner the current reaches to zero the earlier the power supply turns off its voltage for the reversed operation again.
제안 방법
2, a kind of "echo" test has been performed. The test scheme is that the PCS sends a command signal and tries to receive the “echo" returned from the power supply controller, which simply copies the command to the RFM as soon as it receives the command. The PCS was run at the fastest operable cycle, 50 microseconds, to measure the average delay for this communication loop.
대상 데이터
These were performed as part of the SC AC loss measurements. The PF1, PF5 and PF6 were selected for the test. Figure 5 shows snapshots of the waveforms used on the PF1 AC loss measurements.
성능/효과
The PCS was run at the fastest operable cycle, 50 microseconds, to measure the average delay for this communication loop. The measured result was about 420 microseconds in average, which is within the maximum expected assuming the communication overhead for the RFM transfer is very small (< 5 microseconds). However the real power supply response, loop (b) in Fig.
후속연구
The responses of the coils and power supplies corresponding to the plasma magnetic controls in plasma discharges are also analyzed for the future upgrades. Further research of both the elimination of this dead time and controls for safe zero-crossing is required for longer and safer plasma operations.
참고문헌 (4)
Lee, G.S. et al, "Design and Construction of the KSTAR Tokamak", Nuclear Fusion, vol. 41, pp. 1515, 2001
Hahn, S.H., et al, "Plasma Control System for "Day-One" Operation of KSTAR Tokamak", Fusion Engineering and Design (submitted), 2008
Choi, J.H., et al, "Overview of Superconducting Magnet Power Supply System for the KSTAR 1st Plasma Experiment," Transactions of the Korean Nuclear Society (accepted), 2008
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