Fundamental studies for the application of quench protection systems based on an active power method for cryocooled LTS coils

Takeuchi, Kazuya; Nanato, N.; Murase, S.; Kim, Seok Beom; Nishijima, G.; Watanabe, Kazuo; Takeuchi, T.; Banno, N.; Kikuchi, A.

doi:10.1016/j.cryogenics.2008.02.002

Cited by 21 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the most common technique for detecting quench, resistive voltage-based techniques have been widely used in lowtemperature superconducting (LTS) coils and magnets [7,8]. Using voltage taps arranged in a superconducting coil or magnet, which is a technique to measure the resistive voltage signal between the taps when a probable quench occurs.…”

Section: Introductionmentioning

confidence: 99%

Quench detection and early warning based on thermoelastic strain rate for HTS tapes thermally triggered by heat spots

Chen¹,

Guan²,

Tong³

et al. 2022

Supercond. Sci. Technol.

View full text Add to dashboard Cite

The rapid detection and comprehensive monitoring of quench onset and evolution in high-temperature superconducting (HTS) materials remain immensely challenging because the normal zone propagation velocity in HTS materials is two or three orders of magnitude less than that in low-temperature superconductors. In this study, we experimentally and numerically explore quench events triggered by heat spots in yttrium barium copper oxide HTS tapes to characterize the quench onset and propagation. A multiplexed fiber Bragg grating sensor with multiple gratings was used to perform highly accurate strain measurements. Conventional voltage and temperature measurements were performed synchronously on the HTS tapes. A systematic comparison of these multifield signals during quench onset and development illustrated that the evolution of thermoelastic strain and strain-rate in HTS tapes captures the quench onset and propagation. A distinct feature was exhibited during the quenching of a pre-tensioned HTS tape: the thermoelastic strain initially relaxed but subsequently increased until the strain rate exhibited a significant slope change, which corresponded to the quench onset time. The thermoelastic strain in a nearly unconstrained HTS tape gradually increased until quenching occurred. A prominent characteristic for detecting quench onset in HTS materials have been revealed based on the change in the slope of the thermoelastic strain-rate or the second derivative of the strain remaining nearly constant. For a pre-tensioned HTS tape, the minimization of the thermoelastic strain or the strain-rate becoming zero may be a predictor that preceded the quench by 1–2 s, which can be, to a certain extent, regarded as an early warning. Another important and novel result was the experimental demonstration of global strain responses distant from the quench location in the pre-tensioned HTS tape, while the temperature and voltage detection are commonly localized methods. The mechanism behind these thermoelastic strain characteristics was further discussed and simulated from the induced Joule heating throughout the quench event. The measurements and numerical predictions suggested a new paradigm of quench detection based on the thermoelastic strain-rate in HTS materials.

show abstract

Section: Introductionmentioning

confidence: 99%

Quench detection and early warning based on thermoelastic strain rate for HTS tapes thermally triggered by heat spots

Chen¹,

Guan²,

Tong³

et al. 2022

Supercond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The phenomenon known as 'quench' is regarded as the most severe condition that can occur in superconducting magnets, which are commonly used in large tokamak fusion devices [1,2]. The function of quench protection systems (QPSs) is to protect the superconducting magnets from being damaged [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

100 kA/10 kV thyristor stack design for the quench protection system in CRAFT

Wei¹,

Meng²,

Li³

et al. 2023

Plasma Sci. Technol.

View full text Add to dashboard Cite

Thyristors have longer lifetime, higher reliability, less maintenance and very high voltage and current rating capabilities compared to other high-power semiconductor devices. As a result, it is very suitable for Quench Protection System (QPS), which protects the superconducting magnet in large fusion device from being damage. In this paper, the design of a 100 kA/10 kV thyristor stack is proposed by both theorical and simulation analysis and experiment verification. Due to the ultra-high electrical performance requirements put forward by Comprehensive Research Facility for Fusion Technology (CRAFT) to QPS, three main issues must be considered: the voltage-balancing problem brought from multiple thyristors in series structure, the junction temperature rising problem brought from extremely high current and reverse recovery phenomenon as the thyristor physical structure. Hence, a series of detailed theoretical analyses, simulations and experiments including thyristor junction temperature prediction method and reverse recovery process modeling are carried out to optimize the design scheme. Finally, the reliability and stability of the thyristor stack are verified by a series of prototype experiments. The results verify the correctness and accuracy of the proposed design methods of the thyristor stack, and also indicate that the proposed thyristor stack can meet the application conditions of 100 kA QPS in CRAFT project.

show abstract

“…In addition to protecting superconducting devices, such a serious accident must be prevented as much as possible. For this purpose, the abnormality monitoring method of superconducting coils used in the past, i.e., the quench detection system [4][5][6][7][8], is insufficient. Therefore, for practical HTS devices, the monitoring and diagnosing system is required to detect the degradation of superconducting properties before the normal transition locally occurs and diagnose the degree of degradation.…”

Section: Introductionmentioning

confidence: 99%

The calculation and measurement of electromagnetic energy flows for investigation of critical current estimation for high-temperature superconducting coil by means of pick-up coils

Omura

Sato²,

Kawagoe³

2022

IOP Conf. Ser.: Mater. Sci. Eng.

View full text Add to dashboard Cite

For practical operations of high-temperature superconducting (HTS) devices, we have proposed a monitoring and diagnosing system to detect the degradations of superconducting properties before normal transitions occur locally in the HTS winding. The proposed system estimates the distributions of critical current indirectly from measurement results of the active power components of the Poynting vector around the monitoring HTS devices conducting ac currents by means of pick-up coils pairs mounted surrounding the HTS devices. For this purpose, it is necessary to solve the inverse problem. In order to estimate the critical current distribution, therefore, it is first necessary to be able to calculate the measurement signal distribution from the critical current distribution of the monitoring coil. This paper first proposes the calculation method of signal distributions measured by our system, next reports the results of the experiments and analysis, which were carried out to verify the validity of the calculation method. A pancake coil wound with Bi-2223 multifilamentary tape exposed to a uniform AC magnetic field was assumed as a monitoring coil in the experiments and analyses. The good agreement between the measured signals obtained from the experiments and the numerical analysis demonstrates the effectiveness of the proposed calculation method of measured signals.

show abstract

Fundamental studies for the application of quench protection systems based on an active power method for cryocooled LTS coils

Cited by 21 publications

References 4 publications

Quench detection and early warning based on thermoelastic strain rate for HTS tapes thermally triggered by heat spots

Quench detection and early warning based on thermoelastic strain rate for HTS tapes thermally triggered by heat spots

100 kA/10 kV thyristor stack design for the quench protection system in CRAFT

The calculation and measurement of electromagnetic energy flows for investigation of critical current estimation for high-temperature superconducting coil by means of pick-up coils

Contact Info

Product

Resources

About