• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.125-128
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• 1999

This paper presents the 2-D analysis of damper transient in superconducting of damper transient in superconducting synchronous generator(SCG) using finite element method. Efficient 2-D analysis model which compensates the leakage flux is proposed for the savign of computation time and memory capacity required in 3-D finite element analysis. The characteristics of damper transient in SCG and the prime role of damper also have been evaluated.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.87-89
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• 2006

We investigated the current limiting characteristics of flux-lock type superconducting fault current limiter(SFCL) according to inductance variation of coil 2. The flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil through an iron core, and the secondary coil is connected to the superconducting element in series. The operation of the flux-lock type SFCL can be divided into the subtractive and the additive polarity winding operations according to the winding directions between the coil 1 and coil 2. The current limiting characteristics in two winding directions were dependent of on the ratio of the number of turns of coil I and coil 2. The fault current increased when the number of turns of coil 2 increased in the subtractive polarity winding. On the contrary, the fault current decreased under the same conditions in case of the additive polarity winding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.806-809
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• 2000

A key technology for achieving commercial Nb$_3$Sn superconducting wires may be driven from fabrication Process of big-scale billets. Sub-element billet with diameter of 200 mm was designed and fabricated. This billet was hot-extruded and drawn. Cu stabilizer tube, Nb barrier tube and 19 sub-elements inserted Sn core were composed for strand. There was no breakage in the strand that was constituted with annealed sub-element. It was need that billet had to treat HIP because of remove of voids and goad contact between Cu and Nb filaments. Ta wound sheet was better than Ta tube thor barrier in the strand. Ic of the Nb$_3$Sn wire at 127, 4.2K was over than 120 A.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.42-46
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• 2002

This research is conducted with the object of Piling up the foundation of design technologies for high temperature superconducting (HTS) power transformer which is thought to be as a powerful power transformer of next generation. In this study, not only the theoretical design of high temperature superconducting (HTS) transformer but also the arrangements of superconducting tape and the cooling method have been conducted. Moreover, electromagnetic analyses using finite element method (FEM) were conducted to confirm the efficiency of the designed transformer.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.600-602
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• 2000

This paper deals with finite element analysis of 2GVA superconducting generator which has slitted electrothermal shield in d-axis. Open emf voltage is calculated and three phase fault is considered to Predict the generator parameters by F.E.M. Results show that quick response excitation could be applied to superconducting generator with slitted electrothermal shield.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04a
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• pp.39-42
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• 2004

The $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin film fabricated by using the sputtering method was compared with the $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin film fabricated by using the evaporation method. In doing the ultra-low deposition because each element can exist on the substrate surface, both the sputtering method and the evaporation method could easily fabricate single phase of the Bi2212 phase. Also, it is cofirmed that by optimizing the deposition condition, each single phase of the Bi2201 phase and the Bi2212 phase can be fabricated, the sticking coefficient of Bi element is clearly related to the changing of substrate temperature and the formation of the Bi2212 phase.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.711-712
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• 2006

For the application of superconducting fault current limiters(SFCLs) to the protection system, quench recovery characteristics of Au/YBCO thin film were investigated. The Au/YBCO thin film was designed as a SFCL element with a bi-spiral pattern. The SFCL element limited the fault current successfully. For the analysis of the recovery to superconducting state, we measured resistance variation of the SFCL element after the quench. In addition, in order to investigate the dependence of quench characteristics of SFCL on the $LN_2$ cooling condition, we measured the recovery time under a pressure of 1, 2 and 3 atm. As the results, the recovery time increased in proportion to the duration of the fault currents. In the sub-cooled condition, while the quench development was exactly the same, the recovery time was shortened as the pressure increased.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.42-47
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• 2008

In this paper, the fault current limiting characteristics for the superconducting fault current limiter(SFCL) using magnetic coupling between two coils were investigated. The SFCL consists of a high-$T_c$ superconducting(HTSC) element and two coils. This SFCL has different characteristics that depend on the connection form, the winding direction and the inductance ratio of two coils. The impedance and the operational current of the SFCL can be adjusted higher or lower than the resistance and the critical current of HTSC element. Therefore, the SFCL can change the amplitude of the limited fault current. To confirm it, the HTSC element was modeled and the fault current limiting characteristics of the SFCL were analysed through computer simulation. It was obtained from the analysis that the connection form and the winding direction of two coils of the SFCL were the important design parameters.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1832-1837
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• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1292-1298
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• 2003

In this paper, dc reactor lot the inductive high-Tc superconducting fault current limiter (SFCL) was optimally designed by finite element method(FEM). The Prototype high-Tc do reactor was manufactured and compared to the results of design. This dc reactor consists of 4∼stacked double pancake coils which are wounded with Bi-2223 wire coated with SUS315L. Kapton tape is used for the insulation of turn to turn and layer to layer. Each pancake is connected in series by soldering Finally, optimal design and manufacture method lot the dc reactor is suggested in this paper. Through the comparison of result of optimal design and experimental result of prototype high-Tc superconducting dc reactor, reliance on the design of the high-Tc dc reactor tot the 1.2 kV/80 A SFCL is proved.