• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.375-380
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• 2004

This paper presents the basic quench protection idea for the HTS(High-Temperature Superconducting) cable. In Korea power system, the transfer capability of transmission line is limited by the voltage stability, and HTS cable could be one of the countermeasure to solve the transfer limit as its higher current capacity and lower impedance[1]. However, the quench characteristic of HTS cable makes HTS cable to loss its superconductivity, and therefore change the impedance of the line and power system operating condition dramatically. This pheonominum threats not only HTS cable safety but also power system security, therefore a proper protection scheme and security control counterplan have to be established before HTS cable implementation. In this paper, the quench characteristics of HTS cable for the fault current based on heat balance equation was established and a proper protection method by FCL(Fault Current Limiter) was suggested.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.693-694
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• 2006

In order to develop a high temperature superconducting(HTS) coil for the fault current limiter(FCL), the over-current characteristics in YBCO coated conductor(CC) with Ni-W alloy substrate are analyzed. The HTS wire is wound by bifilar winding method for resistive current limitation and it is operated in 65K sub-cooled nitrogen. In order to analyze the resistance and the temperature characteristics of the CC wire, an analysis program is developed considering all the composition materials except the buffer layer. Using this program, the temperature rise, the resistance development and the current limitation of CC are calculated depending on the applied voltage and the stabilizer materials. According to the analysis results, under the temperature restriction of 300K, the maximum voltage per meter is determined as 40V/m if the stabilizer is $25{\mu}m$ thick stainless steel at each side. Finally, the wire length needed for the distribution level HTS FCL is estimated.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.16-20
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• 2007

This paper describes protection system of new distribution power system with superconducting power devices such as HTS cable, HTS transformer, HTS-FCL. First of all, this paper investigates protection systems of Korean power system and then do a basic study on relaying systems in the power system with HTS power devices. For the more detailed results, we did the study using EMTDC relaying system modeling from the viewpoint of superconducting power devices application. Then we proposed some solution for a high resistance fault problem.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1998-1999
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• 2007

Before applying the HTS(High Temperature Superconductor) power devices to a real utility network, system analysis should be carried out by some simulation tools. PSCAD/EMTDC simulation tool is one of the most popularized useful analysis tools for electrical power system. Unfortunately the model component for HTS coil is not provided in PSCAD/EMTDC simulation tool. In this paper, EMTDC model component for HTS coil has been developed considering real characteristics of HTS coil like critical current, temperature and magnetic field. The developed model component of HTS coil could be used for power system application. Using the developed model component for HTS coil, we can easily do the simulation of HTS power devices application test in utility with the various inductance, quench current, inner magnetic field, and temperature values, for instances; SMES(Superconducting Magnetic Energy Storage) system, superconducting motor, transformer, and FCL(Fault Current Limiter)

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.55-59
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• 2009

In attempts to closely study the effect of high efficiency, friendly environment HTS(High Temperature Superconducting) cable and SFCL(Superconducting Fault Current Limiters) on power system, several projects were carried out around the world. Promising results have been achieved in terms of cable capacity and reliability. commercial HTS cable and SFCL, however, must not only be only be feasible, but meet practical requirements as well. To facilitate the transition of HTS cable technology from the Lab. to the Real Grid, a New project for applying 22.9kV HTS cables and SFCL to the commercial Power Grid supported by Government has just started in KEPCO. Target of this project is to operate two 22.9kV, 50MVA, 150MVA HTS cables and two 22.9kV 630A, 3000A SFCL in a KEPCO Grid in order to demonstrate its reliability and stable operation. This paper will present the technology for selecting appropriate site and its plan for installation & operating of 22.9kV HTS cables & SFCL in KEPCO Grid.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.59-63
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• 2014

HTS power cable bypass the fault current through the former to protect superconducting tapes. On the other hand, the fault current limiting (FCL) power cable can be considered to mitigate the fault current using its increased inductance and resistance. Using the increased resistance of the cable is similar to the conventional resistive fault current limiter. In case of HTS power cable, the magnetic field of HTS power cable is mostly shielded by the induced current on the shield layer during normal operation. However, quench occurs at the shield layer and its current is kept below its critical current at the fault condition. Consequently, the magnetic field starts to spread out and it generates additional inductive impedance of the cable. The inductive impedance can be enhanced more by installing materials of high magnetic susceptibility around the HTS power cable. It is a concept of SFCL power cable. In this paper, a sample SFCL power cable is suggested and experimental results are presented to investigate the effect of iron cover on the impedance generation. The tests results are analyzed to verify the generation of the inductive and resistive impedance. The analysis results suggest the possible applications of the SFCL power cable to reduce the fault current in a real grid.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.266_267
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• 2009

22.9kV HTS(High Temperature Superconducting) cable and SFCL(Superconducting Fault Current Limiter) will be installed to Icheon 154kV substation for real distribution power system operation in 2010. This paper proposes CLR (Current Limiting Resistance) specification of the SFCL and fault current condition fo the HTS cable for applying to Korean power system.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.25-29
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• 2009

To reduce the power loss in normal state, non-inductively wound high temperature superconducting (HTS) coils are used for fault current limiter (FCL) application. Non-inductively wound coils can be classified into two types: solenoid type and pancake type. These two types have different electrical and thermal and mechanical characteristics due to their winding structure difference. This paper deals with the current limiting characteristics, magnetic field analysis of the two coils. Simulation using finite element method (FEM) was used to analyze the magnetic field distribution and inductance of the coils. Short circuit test using stabilizer-free coated conductor (CC) was also carried out. We can compare the characteristics of the two types of coil by using the data obtained from simulation and short circuit test. We confirmed the feasibility of FCL application by the analysis about the characteristics of non-inductively wound coil using CC.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.19-23
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• 2021

We have studied the breaking system that combines a resistive superconducting fault current limiter (SFCL) and a DC circuit breaker for DC fault current. To verify the design of the 15 kV DC SFCL, which was driven from the previous work, a 500 V DC system was built and a scale-down SFCL were manufactured. The manufactured SFCL module was designed as a bifilar coil which is a structure that minimizes inductive reactance. The manufactured SFCL module has been experiment to verify characteristics of the current-limiting performance in the DC 500 V system. Also, the manufactured FCL module was combined with the DC circuit breaker to be experimented to analyze the breaking performance. As a result of the experiment, when SFCL was combined to the DC circuit breaker, the energy dissipation received by the DC circuit breaker was reduced by up to 84% compared to when the DC circuit breaker operates alone. We are preparing methods and experiments for the optimal method for much higher performance as a future work.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.705-712
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• 2003

Analysis for the thermal stress distribution in the laminated plates containing a hot-spot(local heating region) is performed. It is assumed that the local heating region induces only mechanical stress by the thermal expansion but effect of the thermal conduction is neglected. The region is regarded equivalent to a homogeneous inclusion expanding in a laminated medium. As an example, Au/YBCO/Al$_2$O$_3$laminate which is often employed for High Temperature Superconducting Fault Current Limiter(HTS FCL) has been analyzed. Effects of heat input, thickness of each layer and the got spot size upon the stress distribution in the hot-spot have been investigated. For a constant heat generation into the hot-spot, as the thickness of the Al$_2$O$_3$substrate increases, the stress in the YBCO layer is peculiarly oscillated, and the curvature of laminate has a maximum at a certain thickness of the Al$_2$O$_3$.