• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.794-795
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• 2011

The DC side voltage and current of a HVDC transmission system are directly affected by non-linear switching devices such as the thyristor valve which causes real power losses, even under the superconducting conditions of a high temperature superconducting (HTS) power cable. This paper deals with the development of miniaturized superconducting DC cable system. The authors designed and fabricated two thyristor converters for DC transmission system. One is operated as a rectifier and the other is an inverter. The HTS model cable was connected between the DC side of the rectifier and inverter. Real DC transport current and voltage were applied to the miniaturized HTS DC cable. Experimental results are discussed in detail.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.236-242
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• 2000

NZP velocities were investigated on Ag sheathed multi filamentary Bi-2223 tape and direction type HTS cable. The critical current($I_c$) of Ag sheathed Bi-2223 tape and direction type HTS cable were 12 A, 63 A at 77 K, 0 T. NZP velocities of tape with two condition of DC and AC were almost same at each temperature. In case of DC, the NZP velocities of numerical analysis and experiment were almost same. NZP velocities of direction type HTS cable were 1.9-2.4 cm/sec. The result shows that the total transport current of spiral type HTS cable in $LN_2$ was 475[A], and transport current passed through almost the outer layer (2-layer). Also, AC transport losses in outer layer of HTS cable was proportion to $I^2$ and higher than losses of inner layer. And in case of $I_p=I_c$, calculated numerical loss density was concentrated on the edge of tape and most of loss density in cable was distributed outer layer more than inner layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.4
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• pp.345-350
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• 2001

Normal zone propagaton(NZP) properties were investigated on Bi-223/Ag tapes and prototype HTS cable. NZP experiments in tape were conducted in temperatures from 45K to 77K in zero field. Prototype HTS cable was molded using epoxy and the experiments were carried out under adiabatic condition in LN$_2$. NZP velocities in tapes with tow conditions of DC and AC currents were almost same at each temperature. NZP velocity in prototype HTS cable was 1.9-2.4 cm/sec in LN$_2$. Numerical analysis was carried out by a one-dimensional equation of heat balance. The simulation results of NZP velocity in Bi-2223/Ag tapes were similar to the experimental results.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.15-18
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• 2003

HTS(High Temperature Superconductor) tapes have dependence on critical characteristics such as electric, magnetic field and temperature. In order to confirm these effects, we examined the current transport characteristics of HTS tapes. First, after being fed DC and AC, the dependence of HTS tapes of 10cm on external magnetic field was investigated. On centeral region of HTS tape, about 1cm, external magnetic field was applied. Second, after applying DC of 50A to HTS tapes, we applied time variable magnetic field about 100mT and investigated the quench characteristics. Finally, AC, which is about 10 times of I$_{c}$, was applied to HTS tapes and over current characteristics were investigated. The data acquired in this study will be used as a source for the study of HTS cable conductor which is supposed to carry on.n.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.50-54
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• 2022

High temperature superconducting (HTS) magnets for large-capacity energy storage system need to be composed of toroid magnets with high energy density, low leakage magnetic fields, and easy installation. To realize such a large capacity of a toroid HTS magnet, an HTS cable with large current capacity would be preferred because of the limited DC link voltage and instantaneous high power required for compensation of the disturbance in the power grid. In this paper, the optimal operating strategies of the SMES for peak load reduction of the microgrid system were calculated according to the load variation characteristics, and the effect of compensation of the frequency change in microgrid with a SMES were also simulated. Based on the result of the simulation, key design parameters of SMES coil were presented for two cases to define the specification of the HTS cable with large current capacities for winding of HTS toroid coils, which will be need for development of the HTS cable as a future work.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.280-284
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• 2000

The prototype high-T$_c$ superconducting (HTS) power transmission cables have been designed and fabricated multi layers of spirally wound HTS tapes. The cables were made Bi-2223 based Ag-sheathed HTS tapes, and tested in LN$_2$. Critical currents of 700A dc and better were achieved. The magnetic flux density and field direction were analyzed in the cable configuration. In this paper the results of analysis and tests of HTS power transmission cables were described.

• Progress in Superconductivity and Cryogenics
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• v.14 no.4
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• pp.32-35
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• 2012

A high-$T_c$ superconducting (HTS) DC application has advantages such as the ultimately lower loss, more compact dimensions, and large capacity compared to AC application. In order to optimize the insulation design of a HTS DC machines, it is important to understand the high voltage insulation and materials at cryogenic temperature. Polypropylene laminated paper (PPLP) has been widely used as an insulating material for HTS AC machines. However, the fundamental data under DC voltage have not been revealed satisfactorily until now. In this paper, we will discuss mainly on the breakdown and dielectric characteristics of PPLP in liquid nitrogen ($LN_2$). The polarity effects of DC and impulse voltage were studied by using the semi-rod to cylindrical electrode. The volume resistivity of PPLP in $LN_2$ was studied. Also, the space charge distribution at room temperature was studied. However, it is necessary to study this topic at cryogenic temperature in the near future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.287-287
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• 2008

HTS-케이블은 구리도체 대신 고온초전도도체를 사용하여 저항이 0이 되는 초전도현상을 이용하여 대용량 전력수송이 가능한 전력케이블로서 대도시의 전력부하 집중문제를 해결할 수 있는 환경 친화적 전력케이블이다. 최근 고온초전도선재의 고임계전류밀도화 및 장척화에 힘입어 HTS-케이블의 실용화를 목표로 경제성이 있는 전력케이블을 개발하려는 움직임뿐만 아니라 실증시험 등 활발한 연구가 진행 중이다. 그러나 초전도전력케이블에서 발생되는 교류손실은 케이블의 효율을 저하시킬 뿐만 아니라 냉동기비용 증가로 인한 기존 케이블과의 가격경쟁에서 경제성을 저하시키는 주된 요인으로 작용하기 때문에 이의 상용화에 앞서 교류손실에 대한 정확한 규명이 되어야 하며 또한 실계통 투입 시 중요한 선로임피던스에 대한 정확한 규명도 필요하다. 본 논문에서는 실제 한전 주관으로 고창시험장에 설치된 배전급 22.9 kV, 100 m, 50 MVA급 3 상 HTS-케이블에 대한 통전특성을 규명하기 위하여 먼저 HTS-케이블의 DC 통전특성을 조사하였다. 또한 3상평형운전상태에서 AC 통전특성(인덕턴스 및 교류손실)을 실험적으로 조사하였으며 5m-케이블에서 측정된 결과와 비교 검토하였다.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.46-49
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• 2009

A 3-phase 100m long, 22.9kV class HTS power transmission cable system was developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. those are participated in the 21st Century Frontier project R&D Program of Korea. It is important to test the DC critical current related with its power capacity before applying to the real power grid. In 1995, several international standards organizations including International Electrotechnical Commission (IEC), decided to unify the use of statistical terms related with 'accuracy' or 'precision' in their standards. It was decided to use the word 'uncertainty' for all quantitative (associated with a number) statistical expressions. In this paper, we measured DC critical current of 22.9kV/50MVA superconducting power cable with several voltage tap and analyzed the uncertainty with these results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.448-451
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• 2000

Normal zone propagation(NZP) characteristics were investigated on Ag sheathed Bi-2223 tape and cylindrical stacked conductor. Normal zone propagation(N2P) experiments with tape were conducted with refrigerator in temperature from 45 K to 77 K, 0 T. Cylindrical stacked conductor was molding with epoxy and experiments were conducted with adiabatic condition in $LN_2$. NZP velocities of tape with two condition of DC and AC were almost same at each temperature. NZP velocities of cylindrical stacked conductor were 1.9-2.4 cdsec in $LN_2$. Numerical analysis was carried out by a one-dimensional heat balance equation. As a result, simulated results of NZP velocity with Bi-2223 tape were similar to experimental results in DC.