• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.295-300
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• 2007

High temperature superconducting (HTS) windings for an HTS transformer which have been developed have two kinds of type, one is the layer winding and the other is disk winding. The layer winding has adopted for an HTS power transformer so far because of the small AC losses of the HTS windings. The disk windings have surface of the HTS wire. We propose a new winding method for a high voltage HTS transformer which has advantages of both type of HTS windings, and we call it continuous disk winding. This new HTS winding consists of pile of HTS disk windings. The continuous disk winding was fabricated with multi-stacked HTS wires for dover HTS transformer. We can check the potential possibility from the characteristic test of the fabricated winding. The new type HTS windings can be applied to HTS power transformers, especially to the high voltage ones.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.903-905
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• 2002

According to the improvement of the HTS wires performance, several types of HTS superconducting machines, such as, transformer, motors, current limiters, and transmission cables are being developed. Degradation of the critical current in HTS tape owing to external field is very important subject in developing the HTS machines. Considering that stacked HTS tapes are widely used to develop the large HTS machines, the critical current characteristics of stacked HTS tapes in external field need to be examined. In this paper, we present critical current characteristics of 4-stacked HTS tapes which are exposed to the external field. HTS tape with critical current of 4-stacked HTS tape. Test results prove that four times critical current of single HTS tape is smaller than critical current of stacked HTS tape in high external field.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.229-233
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• 2019

Large-scale High Temperature Superconducting (HTS) wind power generators suffer from high electromagnetic force and high torque due to their high current density and low rotational speed. Therefore, the torque and Lorentz force of HTS wind power generators should be carefully investigated. In this paper, we proposed a Performance Evaluation System (PES) to physically test the structural stability of HTS coils with high torque before fabricating the generator. The PES is composed of the part of a pole-pair of the HTS generator for estimating the characteristic of the HTS coil. The 10 MW HTS generator and PES were analyzed using a 3D finite element method software. The performance of the HTS coil was evaluated by comparing the magnetic field distributions, the output power, and torque values of the 10 MW HTS generator and the PES. The magnetic flux densities, output power, and torque values of the HTS coils in the PES were the same as a pole-pair of the 10 MW HTS generator. Therefore, the PES-based evaluation method proposed in this paper can be used to estimate the critical characteristics of the HTS generator under high magnetic field and high torque before manufacturing the HTS wind turbines. These results will be used effectively to research and manufacture large-scale HTS wind turbine generators.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.87-91
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• 2003

According to the improvement of the HTS wires performance, several types of HTS superconducting machines are being developed. Stacked HTS tapes are used to conduct the current of the HTS power machines. To develop the HTS power machines, the critical current characteristics of a stacked HTS tapes in external field need be examined. In this paper, we present effect of the external magnetic field on the critical current of HTS stacked tapes. The critical current of various Hinds of multi-stacked HTS tapes in external magnetic filed are compare with that of a single HTS tape. Test results show that critical current of single HTS tape is smaller than that of multi-stacked HTS tape in the external field.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.33-37
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• 2004

This paper presents the construction and test results of an HTS induction motor. End rings and short bars were made of HTS tapes, To increase the efficiency and starting torque, HTS tapes can be used as the rotor bars. Because large current is induced in the rotor circuit, HTS tapes quench and high starting torque can be obtained. As the speed of rotor builds up. HTS tapes which are used as short bars become superconducting state again. After the HTS tapes recover from quench, resistance of the rotor circuit is nearly zero. In that case, power loss in rotor circuit is eliminated. Stator of the conventional induction motor was used as the stator of the HTS motor. Rated capacity of the conventional motor was 0.75 kW. Performances of the HTS induction motor were compared with those of the conventional motor with same volume and specification. Test result showed that the speeds of the HTS induction motor were the same with synchronous speed up to 2.6 Nm and 1.788 rpm at 9.7 Nm. It guarantees the high efficiency of the HTS motor. Starting torque of the HTS motor was more than twice of the conventional motor.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.37-40
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• 2004

A 1 MV A single phase high temperature superconducting (HTS) transformer was manufactured and tested. The rated voltages of primary and secondary of the HTS transformer are 22.9 kV and 6.6 kV respectively. BSCCO-2223 HTS tape was used for HTS windings of 1 MV A HTS transformer. In order to reduce AC loss generated in the HTS winding, the type of concentric arrangement winding was adopted to a 1 MV A HTS transformer. Single HTS tape for primary windings and 4 parallel HTS tapes for secondary windings were used considering the each rated current of the HTS transformer. A core of HTS transformer was fabricated as a shell type core made of laminated silicon steel plate. And a GFRP cryostat with a room temperature bore was also manufactured. The characteristic tests of 1 MV A HTS transformer were performed such as no load test, short circuit test and several insulation tests at 65 K using sub-cooled liquid nitrogen. From the results of tests, the validity of design of HTS transformer was ascertained.

• Journal of Magnetics
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• v.16 no.2
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• pp.129-133
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• 2011

This paper shows the entire future market volume of the HTS power industry, one of main smart grid equipment, in the case of the final market penetration ratio reaching 100% in the domestic market (South Korea). In this paper, the market penetration ratio is determined using the judgment method, with the market penetration S-curve induced using the Delphi method and the Product Life Cycle from 2011 (supposed launching year, not realistic physical year), to 2050 (expected final target year). This paper analyzes the HTS market penetration ratio of each stage, apparent innovation, early adapters, and the early/late majority and laggard stage, using the S-curve, thus calculating the total future market volume of HTS equipment in the positive sense. Finally, this paper estimates the quantitative analysis results for the HTS4-items (cable, FCL, transformer, rotation machine) of each year within the domestic market.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.658-663
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• 2004

According to the improvement of the HTS wires performance, several tapes of HTS superconducting machines are being developed. Stacked HTS tapes are used as conductor that can flow high current for the HTS power machines. To develop the HTS power machines, the critical current characteristics of a stacked HTS tapes in external filed and AC losses should be examined. In this paper, we present characteristic of the stacked HTS tapes and AC losses of HTS pancake windings with stacked tapes. AC loss of the pancake winding were measured and compared with the calculated loss by using AC loss data of the stacked samples and the magnetic flux density in the HTS winding under operating conditions. We can see that measured results generally agree well with the calculated results by using AC loss data of 4-stacked sample.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.507-512
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• 2004

HTS (High Temperature Superconducting) Transformer has the several useful characteristics in the viewpoints of technical and economical. Especially, an HTS transformer replaces the copper wire coils in a conventional transformer with lower loss HTS wire. In addition, inexpensive, environmentally benign liquid nitrogen replaces the conventional oil as the electrical insulation (dielectric) and provides the necessary cooling for the HTS transformer Therefore, the Life-cycle cost of an HTS transformer is much more attractive than conventional because it is more energy efficient, lighter in weight, smaller in size, and environmentally compliant. HTS transformer can be the best way to replace with conventional transformer in the future. In these days, companies world-wide have conducted researches on HTS transformer. A development project for a 154kV HTS transformer is proceeding at a research center and university in Korea. In this paper, we investigate the expected price of HTS transformer to have a merit in viewpoint of economic aspect. First, life-cycle cost of conventional transformer is calculated and based on this, the expected price of HTS transformer is evaluated. which HTS transformer is competitive against conventional transformer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1236-1240
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• 2007

In order to evaluate if the high-Tc superconducting(HTS) power cable is operating stably, the characteristics of the HTS power cable should be found out. The properties of HTS tapes by measuring the voltage with respect to the current can be archived. But, the HTS power cable is different from the case of HTS tapes. This method is invalid because of the electromagnetic fields caused by other HTS tapes. In this paper, the stability evaluation of the HTS cable was performed by the following procedure. First, the voltage-current characteristics of HTS tape were measured and the electromagnetic field distributions of the HTS power cable with the external magnetic field were analyzed. Second, the losses of the HTS power cable were calculated using the result of the measurement and the analysis. Finally, the stable operation of the HTS power cable was evaluated on the basis of the losses of the superconducting cable.