A. Ninomiya

S. Naruo

S. Yamada

T. Ishigohka

T. Mito

Y. Uriu

National Institute for Fusion Science (NIFS-Repository)

§21. State Estimation of Superconducting Coil by Highly Utilization of Voltage and Acoustic Signal Ishigohka, T., Uriu, Y., Ninomiya, A., Naruo, S. (Seikei Univ.), Mito, T., Yamada, S. In the LHD superoonducting system which is romposed of a number of large superoonducting roils, a high-perl'onnanre state estimation system of a superoonducting roil is essentially important To obtain a highly reliable state estimation system, a traditional quench detection system monitoring only voltage signal itself would not be sufficient In such a situation, the authors have proposed to introdure a new estimation factor into the quench detection system. In order to improve the state estimation of superoonducting roil, a utilization of voltage signal and acoustic signal would be effective. Unfortunately, in the LIID superoonducting roils, any AE seruors are not attached Therefore we roncentrated our effort on the highly utilization of electric signals from the superoonducting roil. Targeting more precise state estimation ofH-I roil (Inner Helical roil), we introduced a new roncept of the equivalent aocumulated heat The equivalent aocumulated heat WI€ is calculated by Equation (1). T-t W == [e --. . vi . dt elf 0 where, T: present time [s] v: balance voltage [V] i: roil current [A] 'r: heat dissipation time ronstant [s]. (1) In an actual calculation, we areumulated discretely the heat generated in a period dt following Equation (2). Iv. . e _n;l& + V e _n~2At + .... j W == 1 2 X/.f1t elf 1 - - At ... +Vn-1e r + Vn (2) The calculated equivalent areumulated heat is used as the fourth input variable for the Fuzzy system in addition to the balance voltage, the current, and the liquid helium pressure. The calculated "dangerous rate" of the roil is displayed on a CRT as shown in Fig. 1. -'.;-~:·t r. ~!4i ~ ~ ~: I~'~ l··, l.O ,.:, ..... ,,'~, .. ,. _ .. 8 ,··1' .tJ. ,~ ! Uf Fig. 1. CRT display of dangerous rate of superoonducting roil. The "dangerous rate" calculated introducing the equivalent accumulated heat is shown in Fig. 2, and, that in case of without it is shown in Fig. 3. From these two figures, it can be understood that in case of introducing the equivalent aocumulated heat the dangerous rate increases exceeding 0.5 (the alann level) about 20 [s] earlier than in case of without it 0.8 0.7 Q) 0.6 ~ 0.5 (f) ::l 0.4 o '-~ 0.3 c ~ 0.2 0 .1 o o til 1 11 I Jl J~ 10 20 30 40 50 time (s) ,w ""- 1.1 .J JlU 60 70 80 Fig. 2 Calculated dangerous rate in the new system introducing equivalent aocumulated heat Q) 0.9 0.7 ro 0.6 '-0.5 A. ~ .IJ ~ W 1 Where V, v: v: ....... V are the balance voltages at each ~o 0.4 ' l' 2' 3 ' n '-sampling time. For the heat dissipation time ronstant 'r, we applied the value 1 [s]. And, the sampling time Llt was selected to be 0.1 [s]. Meanwhile, we decided to ronsider the preceding heat until it decays lower than 11100 of the initial _ n-l& value. So, from the rondition e r < 0.01, and Llt = 0.1, 'r = 1 [s], we obtain n = 50. 108 ~ 0.3 c ~ 0.2 0.1 10 20 30 40 50 50 70 80 t i rae (s) Fig. 3 Calculated dangerous rate in the old system without equivalent aocumulated heat 

State Estimation of Superconducting Coil by Highly Utilization of Voltage and Acoustic Signal

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