• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.904-908
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• 2013

When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through a high-capacity and high-$T_c$ superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate measure to protect it. Therefore, appropriate measures are needed to protect HTS cables. The fault-current-limiting HTS cable that was suggested in this study performs an ideal transport current function in normal operations and plays a role in limiting a fault current in abnormal operation (i.e., when a fault current is applied). It has a structure that facilitated its self-current-limiting ability through device change and reconfiguration in the existing HTS cable without extra switching equipment. To complete this structure, it is essential to investigate about the selection of the superconducting wire. Therefore, in this paper, HTS wire using two types of different stabilization layer is compared and examined the stability and current limiting properties under the existence of a fault current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.10
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• pp.657-661
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• 2014

When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through high-Tc superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate method to protect it. The fault-current-limiting type HTS cable that is suggested in this study has a structure of transport part and limit part. It conduct a zero impedance transport current at ordinary operations and carry out a fault current limiting at extraordinary operations. To make a perfect this structure, it is essential to investigate electrical properties of transport part that comprise the fault-current-limiting type HTS cable. In this paper, transport part that comprise HTS wire with copper stabilization layer is examined the current transport properties and the stability evaluation.

• Progress in Superconductivity and Cryogenics
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• v.21 no.4
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• pp.59-63
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• 2019

To reduce the fault current below the current capacity of a circuit breaker, researches on HTS (High Temperature Superconductor) power cables with fault current limiting (FCL) function are increasing. An FCL HTS power cable transports current with low a impedance during normal operation. Yet, it limits the fault current by an increased inductive or resistive impedance of conducting layer when quench occurs at the FCL HTS power cable by the large fault current. An inductive type FCL HTS power cable uses increased inductive impendence caused by leakage magnetic flux outside the cable core when the quench occurs at a shield layer losing the magnetic shielding effect. Therefore, it has an advantage of less resistive heating than resistive type FCL HTS power cable and temperature increase is suppressed. This paper describes an ideal circuit model for the FCL HTS power cable to investigate the effectiveness of increased inductive impedance when quench occurs at the shield layer. Then, FEM analysis is presented with a simplified model cable composed of various iron yokes to investigate the effect of the shape of yoke on the generation of the inductive impedance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.191-195
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• 2015

Inside the existing superconducting cables, the superconducting wire carries a loss-free current, and the cable former (the stranded copper wire) bypasses the fault current to prevent damage and loss of the superconducting cable when the fault current is applied. The fault-current-limiting-type superconducting cable proposed in this paper usually carries a steady current; but in a fault state, the cable generates self-resistance that makes the fault current lower than a certain width. That is, the superconducting cable that transmitted only a low voltage and a large capacity power repetitively limits the fault current, as does a superconducting current limiter. To complete this structure, it is essential to investigate the mutual resistance relationship between the superconducting wires after applying a fault current. Therefore, in this paper, one kinds of superconducting wires (a wire without a stabilization layer) were connected parallel 4 tapes, respectively; and after applying a fault current, the current, voltage, resistance and thermal stability of the HTS thin-film wires were examined.

• Progress in Superconductivity and Cryogenics
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• v.22 no.1
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• pp.7-11
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• 2020

As demand for electricity in urban areas increases, it is necessary to improve electric power stability by interconnecting neighboring substations and high temperature superconductor (HTS) power cables are considered as a promising option due to its large power capacity. However, the interconnection of substations reduces grid impedance and expected fault current is over 45 kA, which exceeds the capacity of a circuit breaker in Korean grid. To reduce the fault current below 45 kA, a HTS power cable having a fault current limiting (FCL) function is considered by as a feasible solution for the interconnection of substations. In this study, a FCL HTS power cable of 600 MVA/154 kV, transmission level class, is considered to reduce the fault current from 63 kA to less than 45 kA by generating an impedance over 1 Ωwhen the fault current is induced. For the thermal design of FCL HTS power cable, a parametric study is conducted to meet a required temperature limit and impedance by modifying the cable core from usual HTS power cables which are designed to bypass the fault current through cable former. The analysis results give a minimum cable length and an area of stainless steel former to suppress the temperature of cable below a design limit.

• 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.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.50-54
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• 2009

In Korea, 22.9kV 50MVA HTS (High Temperature Superconducting) cables and 630A/3kA hybrid SFCLs (Superconducting Fault Current Limiters) have been or are being developed by LS Cable, LS Industrial System, and Korea Electric Power Research Institute. They will be installed at Icheon 154kV Substation for real-power-distribution-system operation in 2010. This paper proposes specification of current limiting resistor/reactor for the SFCL and fault current condition of the HTS cable for applying the superconducting devices to Korean power distribution system, from the viewpoint of power system protection.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.37-39
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• 2007

In the faults of power line, single line ground and line-to-line fault make power system to unbalanced. These fault currents make unbalanced power system. This paper suggests the simulation results of dynamic characteristic of HTS cable system under unbalanced faults condition using EMTDC, Quench phenomenon and current limiting effects are observed. However, quench on the HTS is destroy cable system, coordination with SFCL has to be considered.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.243-244
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• 2006

As an preliminary study for the quench protection of high temperature superconducting (HTS) cable using superconducting fault current limiter (SFCL), experimental research was carried out. The test circuit was composed of Bi-2223/Ag HTS tape and a SFCL made of YBCO thin films. In the normal state, the applied current of 56 A, which was critical current of HTS tape, could be flown through the circuit without resistive loss. Increasing the currents, the quench development of both materials was investigated from the voltage signal acquired from the resistance of the quenched superconductor. Up to around 10 times of the critical current was applied to the HTS tape and the current limiting characteristics of SFCL were investigated. In addition, for the finding out the optimal operating condition of SFCL such as the numbers of elements, a shunt resistor was applied to the SFCL and quench characteristics were analyzed as well.