• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2115-2121
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• 2009

This paper proposes the new reclosing scheme considering the recovery time of SFCL in distribution systems which is based on variable dead time control. The main idea is that it uses the carrier signal to distinguish whether the fault is instantaneous or permanent after tripping the line by recloser. The system and SFCL is modeled by using Electromagnetic Transient Program(EMTP) and the validity of the reclosing scheme presented in this paper is analyzed according to the fault resistance, the recovery time of SFCL and the fault clearing time.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.300-301
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• 2006

Korean power system has some problems like as curtailing investment and the NIMBY (Not In My Back Yard) phenomena, because of power demand concentration in downtown area. In this time, superconducting power devices rise as a very attractive solution. This study proposes a basic concept of superconductivity power system with bulk capacity, and identifies the items for technical and economic analysis. The proposed system consists of superconducting cables/transformers/FCLs(fault current limiter). The basic concept is to replace 154kV conventional cables with 22.9kV superconducting cables and to convert a 154kV substation into a 22.9kV switching station in downtown area.

• 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.

• Progress in Superconductivity and Cryogenics
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• v.14 no.1
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• pp.20-24
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• 2012

This paper proposes an insulation coordination and surge arrester design for superconducting power system with SFCL(Superconducting Fault Current Limiter) in Icheon substation. In the aspect of the economic analysis, since the superconducting devices are very expensive, the insulation coordination to prevent the dielectric breakdown caused by the lightning surge should be considered carefully. In this paper, the insulation coordination for real grid including SFCL and the design of the protection devices against lightning surge is verified using PSCAD/EM TDC.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.22-27
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• 2010

This paper analyzed bus voltage sag caused by recloser-fuse coordination in a power distribution system with SFCL. Generally, the recloser is installed to upstream of fuse to clear against both permanent and temporary faults appropriately, when the fault happened and to block expansion of the fault area. Furthermore, when the fault occurred, bus voltage sag is caused by increased fault currents. However, in a power distribution system with SFCL, the fault current could be decreased by the effect of the impedance value of the SFCL and place to install one as long as it could improve bus voltage sag. Therefore, to analyze the effect of the improvement of bus voltage sag caused by recloser-fuse coordination in a power distribution system with SFCL, we used PSCAD/EMTDC about a permanent fault at the place behind the fuse.

• Progress in Superconductivity and Cryogenics
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• v.8 no.2
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• pp.43-45
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• 2006

Recently, the resistive Fault Current Limiter (SFCL) made with Coated Conductor (CC) has been researched with an advanced capability in CC. Current limiting elements must be connected in series in order to fabricate the resistive SFCL having large capacity. By the way, unless the applied voltage in the SFCL is distributed to the elements when the fault occurred, those elements will be critically damaged. Thus simultaneous quench of the elements is an important factor to design the resistive SFCL. In this paper, simultaneous quench characteristics of current limiting module by using BSCCO 2223 were researched before manufacturing the resistive SFCL by using CC. At the first fault stage, the elements generated the resistance at the same time. However, the unequal voltage is applied to the each element in process of time. The method is suggested to solve the problem of the unequal distribution. These experimental results will play an important part in developing for the resistive SFCL by using CC.

• Progress in Superconductivity and Cryogenics
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• v.13 no.3
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• pp.10-13
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• 2011

The power demand is steadily increasing due to rapidly develop of industrial field. The ratio of prospected increment of power consumption is over 2.2 % per year from 2007 to 2020 year. The superconducting fault current limiters(SFCLs) should be suggested to be one of promising machines to protect power grid. Four basis tests such as resistivity, short-circuit tests, ac losses and recovery time were investigated according to various reached maximum temperature, operating temperature. This paper deals with investigation of the various commercial high temperature superconductor for applying resistive type SFCLs.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.91-94
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• 2000

We fabricated resistive super- conducting fault current limiters (SFCL) based on YBCO thin films grown on 2" diameter $Al_{2}O_{3}$ substrates. Two SFCLs with nearly identical properties. two SFCLs with nearly identical properties were connected in series to investigate simultaneous quenching. There was a difference of several half cycles in their quench starting time, although the difference was not more than 0.1 msec when they were operated separately. This imbalance was removed by connecting a shunt resistor to an SFCL in parallel. Increased power input at high voltages also reduced the initial imbalance in power dissipation. Further efforts on the simultaneous quench in SFCLs connected in series are on the way through methods such as the artificial control of quench speed.peed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.214-219
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• 2012

In this paper, the method of protective coordination is studied to install Superconducting Fault Current Limiter (SFCL) to power distribution system. If SFCL is installed, the protective coordination is not operated well because of the decreased fault current. Thus, the resetting method of protective devices is presented to coordinate protection system in power distribution system with resistor-type SFCL. The presented methods are divided into three parts; OCR, OCR-Recloser, OCR-Recloser-Recloser. The presented methods are proved through case studies using PSCAD/EMTDC simulation.

• Progress in Superconductivity
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• v.6 no.1
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• pp.46-51
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• 2004

We fabricated a resistive type superconducting fault current limiter (SFCL) of 3-phase $6.6 kV_{rms}$ / rating, based on YBCO thin films grown on sapphire substrates with a diameter off inch. Each element of the SFCL was designed to have the rated voltage of $600 V_{rms}$ $/35A_{rms}$. The elements produced a single phase with 8${\times}$6 components connected in series and parallel. In addition, a NiCr shunt resistor of 23 $\Omega$ was connected in parallel to each of them for simultaneous quenches between the elements. Prior to investigating the performance of the 3 phase SFCL, we examined the quench characteristics for 8 elements connected in series. For all elements, simultaneous quenches and equal voltage distribution within 10% deviation from the average were obtained. Based on these results, performance of the SFCL for single line-to-ground faults was investigated. The SFCL successfully limited the fault current of $10 kA_{ rms}$ below 816 $A_{peak}$ within 0.12 msec right after the fault occurred. During the quench process, average temperature of all components did not exceed 250 K, and the SFCL was totally safe during the whole operation.