• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.501-502
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• 2011

Based on the several advantages of high-temperature superconducting cable, there are many researches about HTS cable. In the aspect of power system engineering, since it has very low impedance, approximately zero, it is profitable for large capacity distribution line into the large scale load. In the step of its verifications, the HTS cable had been installed in Icheon substation and operated. In this paper, the protection coordination for Icheon substation had been designed and verified using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.961-963
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• 2002

When high temperature superconducting(HTS) tapes are wound on former for HTS cable application, their critical characteristics are likely to be degraded seriously because of mechanical stress. In this study, prior to fabricate prototype HTS cables, we investigated the variation of critical characteristics of HTS tapes according to their pitch angles. For this work, we prepared the samples of HTS tapes on the former of which diameter is 3cm. Pitch angles of HTS tapes are $0^{\circ}$, $00^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$, respectively. We applied current up to 160 $A_{rms}$ to HTS tapes and investigated E-I characteristics. The critical current of HTS tapes was decreased as pitch angle increased. In addition, when the applied current was beyond their critical current, the rate of resistance increase of HTS tapes was in proportion to their critical current. Finally, We concluded that the pitch angles affected resistance increase of HTS tapes as well as critical current.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1626-1628
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• 1998

In reccent years the large capacity underground power transmission systems have been required gradually with the increasing demand of electric power, the increasing electric power system and the environmental limitations of an overhead transmission line in the city. But it is difficult to get the space for the underground power transmission lines because of complicated distributions of underground public facilities. But as the superconducting power cables have the large power transmission capacity, the high power transmission density, and low loss characteristics in comparison with a conventional cable, the necessity for their development are increasing. In this paper, the results of the conceptual design of HTS power cable is described.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.397_398
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• 2009

Demonstrations to deploy high temperature superconducting (HTS) cable to the real gird are actively carried out throughout the world. Power utilities have an interest in the inherent advantage of the HTS cable system, and achieve the expected results from the series of verification test. To embody the reliability in the phenomenon occurred commonly in three-phase system, we simulate the load unbalance. A 22.9 kV large scale HTS cable system with the specification of 100 m-long, 50 MVA capacity has been tested with up to 30% unbalance rate. To evaluate the effect of AC loss increase due to the unbalanced load, the cooling loads are measured by the calorimetry method. In this paper, the correlation between AC loss and load unbalance is described and investigated precisely.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.331-336
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• 2004

Due to the outstanding insulating characteristics, Laminated Polypropylene paper (LPP) and Kraft paper have been used as ac power insulation for conventional cable. Recently, both of LPP and Kraft has been studied as main insulation fur high temperature superconducting (HTS) cable. Ifowever, studies on the use of LPP/Kraft paper for HTS cables are thinly scattered. In this paper, the comparison among LPP, Kraft and LPP/Kraft Samples impregnated with liquid nitrogen $(LN_2)$ on dielectric insulation characteristics was investigated. It was found from the experimental data that the breakdown strength becomes lower in the order LPP, Lpp/Kraft and Kraft but the lifetime indices n becomes lower in the order Kraft, LPP/Kraft, LPP. Moreover, partial discharge inception and dielectric loss tangent become lower in the order Kraft, LPP, LPP/Kraft.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.87-93
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• 2004

Laminated Polypropylene Paper (LPP) and Kraft paper were used as ac power insulation for conventional cable as well as high temperature superconducting (HTS) cable because of its prominent insulating characteristics. However, researches on the use of LPP/Kraft paper in HTS cables are thinly scattered. In this paper, the effect of laminate polypropylene paper on the breakdown strength of LPP/Kraft multi-layer sample impregnated with liquid nitrogen (LN2)under ac and impulse applied voltage was studied. In addition, the breakdown strength characteristics of LPP and Kraft multi-layer sample were also investigated. It was found from the experimental data that the LPP has higher breakdown strength value than Kraft paper in ac and impulse. Especially in the ac case, the breakdown strength increases as the component ratio of LPP in the LPP/Kraftsample increases and slightly affected by the inserting position of LPP but in impulse case, the breakdown strength strongly depends on the number of LPP and the relative position of LPP.

• 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.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.

• Progress in Superconductivity and Cryogenics
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• v.9 no.4
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• pp.41-45
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• 2007

Superconductor is developed for applications in high-power devices such as power-transmission cables, transformers, motor and generators. In such applications, HTS tapes are subjected to various kinds of stress or strain. AC loss is also important consideration for many large-scale superconducting devices. In the fabrication of the devices, the critical current $(I_c)$ of the high temperature superconductor degrades due to many reasons including the tension applied by bending and thermal contraction. These bending or tension reduces the $I_c$ of superconducting wire and the $I_c$ degradation affects the AC loss of the wire. The $I_c$ degradation and AC loss (self field loss) of Bi-2223 HTS and Coated conductor were measured under tension and bending conditions at 77K and self-field.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.41-43
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• 2009

The HTS power cable system of 3-phase 100-m class has been tested at the KEPCO's Gochang power testing center in Korea during 8,000 hours or more for investigating long-term operating performance. The system is rated 22.9kV, 1250A and is cooled with sub cooled liquid nitrogen. Several cooling performance tests such as cooling capacity, heat load, AC loss, temperature stability and thermal cycle were performed at operating temperature of 66.4K and several different temperatures.