Quench Behavior and Protection in Cryocooler-Cooled YBCO Pancake Coil for SMES

Ishiyama, Atsushi; Ueda, Hiroshi; Aoki, Yuji; Shikimachi, K.; Hirano, Naoki; Nagaya, S.

doi:10.1109/tasc.2010.2093491

Cited by 27 publications

(6 citation statements)

References 10 publications

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“…Therefore, a quench must be detected using some other method. In the previous paper, we showed that a quench in the coil could be detected by observing the transposition of the current in the bundle conductor caused by local normal transition [5]. After a quench is detected by observing a non-uniform current, the stored energy of the coil is dumped on the external resistance.…”

Section: B Quench Detectionmentioning

confidence: 99%

“…Moreover, we have investigated the redistribution characteristics of the transport current in, and the thermal behavior of, a coil wound during a quench and discussed a quench detection method by observing a non-uniform current in the coil [4], [5]. In this paper, based on these studies, we investigate the transposition of the current and the thermal behavior during a dump and determine the appropriate stabilizer thickness for the YBCO-coated conductors.…”

Section: Introductionmentioning

confidence: 99%

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Quench Detection and Protection of Cryocooler-Cooled YBCO Pancake Coil for SMES

Ueda

Ishiyama

Muromachi

et al. 2012

IEEE Trans. Appl. Supercond.

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In this paper, we focus on the quench detection and protection of a cryocooler-cooled pancake coil for SMES wound with a YBCO bundle conductor composed of laminated electrically insulated YBCO-coated conductors. Because the normal-zone propagation velocity is much slower in a high-temperature superconducting (HTS) coil than in a low-temperature superconducting (LTS) coil, the detection of the non-recovering normal zone using a voltage signal is quite difficult. Quench detection is considered to be more difficult during SMES operation because of the noise of the converter or other equipment. Therefore, a quench must be detected using some other method. In the previous paper, we showed that a quench in the coil could be detected by observing the transposition of the current in the bundle conductor caused by local normal transition. In this paper, based on this quench detection method, we investigate the transposition of current and the thermal behavior during the quench detection and the dumping of the stored energy by an external resistance in coils wound with a YBCO laminated bundle conductor for SMES and determine the appropriate stabilizer thickness of the YBCO-coated conductors.

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Section: B Quench Detectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quench Detection and Protection of Cryocooler-Cooled YBCO Pancake Coil for SMES

Ueda

Ishiyama

Muromachi

et al. 2012

IEEE Trans. Appl. Supercond.

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“…Since the inductance of a PWNI coil is significantly decreased with the reduced number of turns compared with a single-wound NI coil (SWNI) of identical size, the charging delay can be significantly suppressed [37,38]. Some studies have used numerical simulation methods to analyze the external electromagnetic characteristics of PWNI coils, such as central magnetic field and coil voltage [39][40][41]. The azimuthal current distribution among different turns in PWNI coils at certain times has been analyzed by the circuit network model [42,43].…”

Section: Introductionmentioning

confidence: 99%

Non-uniform current distribution in parallel-wound no-insulation high-temperature superconductor coil during ramping and fast discharging operations

Fu,

Wang,

Peng

et al. 2023

Supercond. Sci. Technol.

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A parallel-wound no-insulation (PWNI) high-temperature superconductor (HTS) coil is a kind of pancake-shaped no-insulation (NI) coil wound with parallel-stacked HTS tapes, which combines the characteristics of a NI coil and non-twisted stacked-tape cable. It shows a significant advantage in accelerating the ramping response compared with traditional NI HTS coils wound by a single tape, and is a promising alternative for large-scale high-field magnets. The stacked cable approach can lead to current redistribution between parallel tapes during ramping operations. It couples with the turn-to-turn current redistribution and leads to a much more complicated current redistribution inside the PWNI coil, the mechanism of which remains unclear so far. The aim of this work is to investigate electromagnetic behavior of a PWNI HTS coil in ramping and fast discharging process. A simulation model was developed by integrating an equivalent circuit network model and an improved T–A model. A three-tape PWNI coil and its insulated counterpart were wound and tested, and this model was validated by charging and discharging tests. Results show that there is a significant non-uniform current distribution on parallel tapes in the same turn during ramping operations and the maximum azimuthal current (transport current) can be 2.26 times the minimum one in the three-tape PWNI coil in this study. Meanwhile, the radial current shows a considerable accumulation in the tape near turn-to-turn contacts and the radial current through the turn-to-turn contacts can be 4.16 times of that the flow through tape-to-tape contacts (parallel tapes) in the same turn. During the fast discharging process, a significant coupling current is generated in the PWNI coil, leading to a large opposite transport current in local areas; the amplitude of variation of this can be 4.66 times the initial operating current. The radial current shows a similar distribution but opposite direction to that during ramping, and its amplitude is two orders of magnitude higher. These results provide practical guidelines for the design of large-scale high-field HTS magnets.

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“…However, the initiation of thermal runaway in multifilament coated conductors has not been experimentally studied. Furthermore, previous experimental studies on thermal runaway did not directly discuss the conditions under which the conventional quench detection and protection scheme (i.e., detecting quench/thermal runaway using voltage taps and dumping the stored energy in an external dump resistor) could be applied [22][23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Thermal Runaway of Conduction-Cooled Monofilament and Multifilament Coated Conductors

Luo

Zhao

Sogabe

et al. 2022

IEEE Trans. Appl. Supercond.

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We experimentally studied the thermal runaway initiating at a low critical current (Ic) part. This low Ic part is determined by the combination of two reasons in a real coil: (a) the unavoidable defects caused by the manufacturing process, which reduce local critical currents (and might not be uniform across the width of a coated conductor) and (b) the magnetic field distribution along the coated conductor. To simulate the thermal runaway using a short monofilament/multifilament REBa2Cu3Oy (RE-123) coated conductor, we artificially created a local defect (low Ic part) in a short sample by pressing using a drill bit (creating a defect close to one edge of a coated conductor) or bending (creating a uniform defect across the width of a coated conductor). The sample of the coated conductor was conduction-cooled to 30 K, and a magnetic field was applied (µ0H up to 2 T) perpendicular to the wide face of the conductor to control its critical current. Transverse voltages in a multifilament coated conductor were measured to obtain the transverse currents among the filaments through the copper layer. Thermal runaway currents (operating currents above which thermal runaway initiates) of the monofilament sample and those of the multifilament sample with additional Joule loss due to the transverse currents were determined and compared to study the effect of the transverse currents on the initiation of thermal runaway in the multifilament coated conductor. Experiments on the protection against thermal runaway were conducted. When a normal voltage (over a preset threshold) was detected, the supplied current would be decreased exponentially. The thresholds for protecting monofilament and multifilament coated conductors from degradation after thermal runaway were compared.

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Quench Behavior and Protection in Cryocooler-Cooled YBCO Pancake Coil for SMES

Cited by 27 publications

References 10 publications

Quench Detection and Protection of Cryocooler-Cooled YBCO Pancake Coil for SMES

Quench Detection and Protection of Cryocooler-Cooled YBCO Pancake Coil for SMES

Non-uniform current distribution in parallel-wound no-insulation high-temperature superconductor coil during ramping and fast discharging operations

Thermal Runaway of Conduction-Cooled Monofilament and Multifilament Coated Conductors

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