• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.330-333
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• 2002

This study is concerned with the optimal design of DC reactor type high-Tc superconducting fault current limiter(SFCL) by Newton method. What should be first thought over in developing SFCL is the condition in which the cost function is minimized under given constraints. So, this condition is supposed to be the values corresponding to the variables the cost function counts on. In this paper, we got the result for the SFCL available at the level of 6.6kV-200A by means of simulation.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.56-59
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• 2003

As electric power systems grow to supply the increasing electric power demand short-circuit current tends to increase and impose a severe burden on circuit breakers and power system apparatuses. Thus, all electric equipment in a power system has to he designed to withstand the mechanical and thermal stresses of potential short-circuit currents. Among current limiting devices, Fault Current Limiter (FCL) is expected to reduce the short-circuit current. Especially, Superconducting Fault Current Limiters (SFCL) offer ideal performance: in normal operation the SFCL is in its superconducting state and has negligible impedance, in the event of a fault, the transition into the normal conducting state passively limits the current. The SFCL using high-temperature superconductors offers a positive resolution to controlling fault-current levels on utility distribution and transmission networks. This study contributes to the EMTDC based modeling and simulation method of DC Reactor type SFCL. Single and three phase faults in the utility system with DC reactor type SFCLs have been simulated using EMTDC in order to coordinate with other equipments, and the results are discussed in detail.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1294-1295
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• 2011

This paper describes a conceptual design of 10 MW class gearless type superconducting synchronous generator for wind turbine. The main benefits of gearless type generator are decrease of the process of maintenance and loss caused by drive-train. The designed generator improves efficiency of high-capacity wind turbine by applying superconducting coil making high magnetic field. Conventional wind turbines were investigated for up-scaling of generator and the generator had been designed with estimated design parameters using a finite elements method analysis tool.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.197-199
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• 2007

To apply the flux-lock type SFCL into power system, its current and voltage ratings are required to increase. Especially, in case of series connection of SFCLs, the countermeasure for simultaneous quenches must be considered. The structure, which each flux-lock type SFCL unit was wound in series on the same iron core, can induce the simultaneous quench of superconducting elements. Through the fault current limiting experiment for the suggested structure, it was confirmed that the even voltage burden among the superconducting elements comprising SFCLs could be made.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.339-342
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• 2001

In this paper, the characteristics of the shielded inductive superconducting fault current limiter(FCL) were simulated and analyzed to search for the parameter to determine FCL operation, Fault current limiting operation can be executed as resistive or inductive type, which is determined by iron-core radius and the number of the primary coil turns. It was considered through this paper that the operation of each was compared and examined about the merit of each mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.511-514
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• 2002

In this paper, we compared the characteristic of fault current liminting in the magnetic shielding type High-Tc superconducting fault current limiter(FCL) using both Piecewise linear magnetization curve and real magnetization one of iron core. From this paper, the characteristics of fault current limiting in both cases showed many differences. The latter has higher fault current than the former, because the saturation of iron core was reflected and more accumulated during fault. It is expected that the more exact characteristic of magnetic shielding type High-Tc superconducting FCL was obtained in the case of design and modeling.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.20-25
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• 2000

A CICC type superconducting bus-line electrically connecting a superconducting magnet to a power supply is cooled down to low temperature under the external magnetic field during operation. The thermal contraction during the cooling may be constrained by the supports which are installed to protect the bus-line from Lorenz magnetic forces. This constrained contraction causes thermal stresses in the bus-line to release thermal contraction. The minimum stress conditions in the bus-line may be optimized by controlling the supporting arrangement considering the thermal contraction and the external field. The analytical method to find optimal supports arrangement was suggested by using the beam theory, and numerical calculation using commercial code was performed to verify the suggested analytical optimization method.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.94-98
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• 2002

The Partial breakdown (PBD) and complete breakdown (BD) voltage characteristics in a composite insulation system of glass fiber reinforced plastics (GFRP) and liquid nitrogen are investigated to find the PBB and BD characteristics in solenoid type high temperature superconducting (HTS) coils at quench. The electrode system used is made from a coaxial spiral coil-to-cylindrical electrode with an insulation barrier and spacers, and is immersed in liquid nitrogen. A heater is mounted inside the coil electrode to generate boiling which occurs on quenched superconducting coils. The experimental results show that: (1) breakdown voltages are affected severely by the risetime of the applied voltage and the PBD inception voltage, (2) two kinds of BD mechanisms are found depending on the shape of the spacer, length of cooling channel and heater power.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.665-666
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• 2008

Inserted HTS (high temperature superconducting) coil is promisingly expected as a solution for achievement of higher fields such as GHz scale NMR magnet. However, HTS magnet causes persistent current decay in the persistent current mode and this decay should be compensated in order to keep stable magnetic field. As a solution for the decay in the HTS magnets, we proposed a new type superconducting power supply, i.e., linear type magnetic flux pump (LTMFP). The LTMFP mainly consists of DC bias coil, 3-phase AC coil and superconducting Nb foil. The compensating current in closed superconductive circuit can be easily controlled by the intensity of 3-phase AC current and its frequency. In this study, it has been investigated that the flux pump can effectively charge the current for various frequencies according to the different load magnets.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.232-234
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• 1998

Race-track type superconducting coils are used for wiggler magnets of accelerators and field coils of superconducting generators(S.C.G) and so on. The shape is different from ordinary solenoidal type magnet, so the manufacturing situation and conditions become different and moreover according to these results the output characteristics of magnet also becomes different. In this paper we are dealing with race-track type coil design that is inserted into 30(kVA) S.C.G which will be manufactured before we make l(MVA) S.C.G plant. The design procedure is based on two dimensional electromagnetic analysis including laplace equations in cylindrical coordinate.