• 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 Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.507-510
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• 2002

In economical points of view, AC loss of high temperature superconducting devices is considered as a serious problem that must be solved. Expecially, in case of HTS cables, HTS tapes are wound helically on the former to reduce AC loss. Critical characteristics of HTS tapes, however, are influenced by mechanical stress as well as electrical, temperature, and magnetical factors. The purpose of this study is to investigate the over current characteristics of HTS tapes given mechanical stress when they are wound on the former. We prepared HTS tapes with the pitch angle 20$^{\circ}$, length 25cm as well as tapes with pitch angle 0$^{\circ}$. When current of over 200A$\_$rms/ was applied, we found out that there are differences to the rate of resistance increase between the case of pitch angle 20$^{\circ}$and that of 0$^{\circ}$. The rate of resistance variation in HTS tapes of pitch angle 20$^{\circ}$increased more slowly than that of pitch angle 0$^{\circ}$. As a result, we concluded that if critical characteristics of HTS tapes are degraded by any external factor, when over current is applied, the current limiting characteristics in HTS tapes won't be able to be expected any more.

• Progress in Superconductivity and Cryogenics
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• v.5 no.2
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• pp.8-15
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• 2003

Nowadays, As power demand increases gradually, the call for underground transmission system increases. But it is very difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. HTS cable has the several useful characteristics such as increased power density, stronger magnetic fields and/or reduced losses. Therefore HTS cable can allow more power to be moved in existing ducts, which means very large economical and environmental benefits. In this paper, we investigate the status of korean power system and underground transmission system. Based on this, the feasibility study on applying HTS cable to korean power system is carried out and then we propose the new power system configuration of metropolitan area with HTS cable. Finally, we can get a conclusion that applying HTS cable to 154kV underground transmission line in metropolitan area such as seoul is very available. In addition, detail applicable cases are investigated; a)replace old conventional cable with HTS cable; b) apply HTS cable to constructing new underground transmission line; c)use HTS cable to resolve overload problem in conventional power system configuration.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.75-76
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• 2007

Several kinds of High Temperature Superconducting(HTS) power cables have already been developed and evaluated for use in the utility power network. HTS power cable is expected to be used as a very powerful energy delivery system supplying electric power for densely populated cities in the near future, because HTS power cable is capable of the high current density delivery with low AC loss and the size effect comparing with the conventional cable whose capacity is same. Before applying the HTS power cable to real utility network system analysis should be carried out by some simulation tools. Hereby the electrical power system analysis is very important for the practical use of HTS power devices. In this paper, authors propose a real-time simulation method which incorporates a real HTS tapes into the simulated 22.9kV utility power network system using Real Time Digital Simulator(RTDS). For the simulation analysis, a test sample of HTS tapes was actually manufactured, and the transient phenomenon of HTS power cable system was analyzed in the simulated utility power network.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.10-13
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• 1999

For large scale applications of high temperature superconductor(HTS) such as transmission cables, motors and generators, long length of flexible HTS conductors is required. Currently, HTS tape that is capable of being fabricated in long length by industrial processes is the Bi-2223 HTS tape. In this study, we fabricated 19 filamentary Bi-2223($Bi_{1.8}$$Pb_{0.4}$$Sr_{2}$$Ca_{2}$$Cu_{3}$$O_{10+X}$) HTS tape with 100m length by PIT(Powder In Tube) process. Critical current(Ic) of this long length tape was measured 18.5 A at 77 K, self field and short sample Ic is 32.5 A at the same condition. Critical current of 100m length tape was decreased by about 1/3 compared to that of short tape. This was mainly resulted from the increase of non homogeneity in oxide layer.

• Progress in Superconductivity and Cryogenics
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• v.1 no.2
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• pp.15-19
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• 1999

For large scale applications of high temperature superconductor (HTS) such as transmission cables, motors and generators, long length of flexible HTS conductor is required. Currently, Bi-2223 HTS tape is capable of being fabricated in longer than 100 m length by industrial processes. In this study, we fabricated 100 m 19 filamentary Bi-2223 ($Bi_{1.8}Pb_{0.4}Sr_2Ca_2O_{10+x}$) HTS tape by PIT (Power in Tube) process. Critical current(IC) of this long length tape was measured 18.5 A at 77K, self field. Critical current of 100 m length tape was mainly resulted from the increase of inhomogeneity in oxide from the increase of inhomogeneity in oxide layer. Engineering critical current (Je=Ic/total tape cross-section area) that is important factor for practical applications and fabrication cost was measured 2.2 kA/cm2.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.97-103
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• 2015

This paper introduces two on-going projects for DC high temperature superconducting (HTS) cable systems in South Korea. This study proposes the application of DC HTS cable systems to enhance power transfer limits of a grid-connected offshore wind farm. In order to develop the superconducting DC transmission system model based on HTS power cables, the maximum transfer limits from offshore wind farm are estimated and the system marginal price (SMP) calculated through a Two-Step Power Transfer (TSPT) model based on PV analysis and DC-optimal power flow. The proposed TSPT model will be applied to 2022 KEPCO systems with offshore wind farms.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.129-133
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• 1999

In recent years, there is a growing needs for large capacity underground power transmission lines with the increasing demand of electric power in the urban area, where various environmental limitations are imposed on the overhead transmission lines. But it is difficult to get the space for the underground power transmission cables because of complicated distributions of underground public facilties such as subway, water pipes, gas etc. As the superconducting power cables have the large power transmission capacity, the high power transmission capacity, the high power transmission density, and low loss characteristics in comparison with a conventional cable, it would be a solution to meet the increased power demand. In this paper, the results of the conceptual design and analysis of power system of HTS power transmission cable is described.

• 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.5 no.1
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• pp.107-110
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• 2003

High Temperature Superconductor (HTS) transmission cable can carry more than 2 to 5 times higher electricity and also obtain substantially lower transmission losses than conventional cables. Liquid nitrogen is to be used to cool the HTS power cable and its cost is much cheaper than the liquid helium used for the cooling of metal superconducting wire. In Korea the HTS power cable development project has been ongoing since July, 2001 with the basic specifications of 22.9kV, 50MVA and told dielectric type as the first 3-year stage. The cryogenic system of the HTS cable is composed of HTS cable cryostat termination and refrigeration system. Termination of HTS cable is a connecting part between copper electrical cable at room temperature and HTS cable at liquid nitrogen temperature. In order to design the termination cryostat, it is required that the conduction heat leak and Joule heating on the current lead be reduced, the cryostat be insulated electrically and good vacuum insulation be maintained during long time operation. Heat loads calculations on the copper current lead have been performed by analytical and numerical method and the feasibility study fer the other candidate materials has also been executed.