• 한국초전도학회:학술대회논문집
• /
• 2009.07a
• /
• pp.119-119
• /
• 2009

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1208-1210
• /
• 1999

Design & operation power systems for meeting increase of electric power demand is becoming more difficult and complex. Some of limitations of conventional technology can be broken through by the application of superconductivity technology. This paper presents a new concept & image for the configuration of superconducting power system which has introduced superconducting(SC) generator, cable, transformer, fault current limiter(SFCL), SMES, etc. Engineering evaluation of each power apparatus and its assessment of application to power system were conducted. Futhermore, it is pointed that superconducting power system require a new operating condition. This is, SFCL should play a important part of quenching current level coordination to prevent the other superconducting devices from quenching. Its designing & operating condition including SFCL was discussed in viewpoint of quenching current level and insulation coordination of SC coil.

• Progress in Superconductivity and Cryogenics
• /
• v.14 no.3
• /
• pp.5-8
• /
• 2012

Superconducting windings of synchronous machine have to be operated in below the critical temperature, critical current density and critical magnetic field. If one of these characteristics does not satisfied, then the quench occurred in superconducting winding. Especially the armature current dramatically increased as the superconducting generator is short-circuited at the rated load condition and magnetic field in field winding increased due to the armature current. Therefore, damper is required to reduce the magnetic field of field winding which increases reliability of the superconducting generator. Damper dimension can be decided by time constant[1-2]. In this paper the basic model is high-power and low-speed superconducting generator. Damper time constant was calculated from the changed damper thickness and material. Magnetic flux of field coil at the basic model and changed damper time constant model is analyzed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.8
• /
• pp.107-112
• /
• 2007

The flux-lock type SFCL consists of transformer with primary and secondary windings connected to a superconducting element in serial. It can be divided into the subtractive and the additive polarity windings according to the winding direction. It could change the fault current limiting characteristics according to the inductance ratio between the coil 1 and coil 2. We investigated the voltage-current characteristics of the flux-lock type SFCL according to the increment of applied voltage. When the applied voltage of the SFCL with the subtractive and the additive polarity windings was increased a initial limiting current ($I_{ini}$) and the quench time of the superconducting element were increased. The recovery time of the superconducting element was increased by increment of applied voltage. Therefore, it was confirmed that recovery characteristics in the flux-lock type SFCL were largely dependent on the consumed energy of a superconducting element because of increment of the consumption power into the superconducting element.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.824-825
• /
• 2011

This paper reports advantages of an insulationless high temperature superconductor (HTS) pancake coil compared with an insulated HTS pancake coil. The various characteristics of the insulationless HTS pancake coil were evaluated under charge-discharge conditions. Also over-current test was performed and the results were analysed to demonstrate that in terms of stability insulationless HTS pancake coil outperforms existing insulated HTS pancake coil.

• Journal of Magnetics
• /
• v.13 no.4
• /
• pp.177-181
• /
• 2008

A very simple a.c. magnetic susceptometer for use in a helium closed cycle cryostat is reported in this paper. This simple setup has only a single bobbin-less copper coil, instead of the primary coil and two secondary coils typically used in mutual-inductance types. The single bobbin-less copper coil is directly mounted on the cryostat cold head. A sample is attached on the inside wall of the copper coil using a thermal contact material and its a.c. magnetic susceptibility is obtained from the measurement of the self-inductance of the sample coil using an LCR meter or an impedance analyzer. Experimental details are described and illustrative measurements on magnetic and superconducting materials as a function of temperature are included. The performances and limitations of this simple a.c. magnetic suceptometer are also discussed.

• Progress in Superconductivity and Cryogenics
• /
• v.18 no.1
• /
• pp.46-49
• /
• 2016

The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

• Journal of Korea Society of Industrial Information Systems
• /
• v.24 no.2
• /
• pp.33-40
• /
• 2019

Many companies have tried to develop wind power generators with a larger capacity, smaller size and lighter weight. High temperature superconducting (HTS) generators are more suitable for wind power systems because they can reduce volume and weight compared with conventional generators. However, the HTS generator has problems such as huge vacuum vessel and the difficulty of repairing the HTS field coils. These problems can be overcome through the modularization of the HTS field coil. The HTS module coil require a current leads (CLs) for deliver DC current, which causes a large heat transfer load. Therefore, CLs should be designed optimally for reducing the conduction and Joule heat loads. This paper deals with a structural design and thermal analysis of a module coil for a 750 kW-class HTS generator. The conduction and radiation heat loads of the module coils were analysed using a 3D finite element method program. As a result, the total thermal load was less than the cooling capacity of the cryo-cooler. The design results can be effectively utilized to develop a superconducting generator for wind power generation systems.

• Progress in Superconductivity and Cryogenics
• /
• v.14 no.1
• /
• pp.44-47
• /
• 2012

The substantial improvement of the signal-to-noise ratio (SNR) can be achieved with small-size samples or low-field MRI system by high-temperature superconducting(HTS) RF coil. The typical HTS RF coil made of HTS thin film is expensive and is limited the coil geometry to planar surface coil. In this study, commercial Bi-2223 HTS tapes was used as RF coil for a 0.35T permanent MRI system. It has advantages of both much lower cost and easier fabrication over HTS thin film coil. SNR gain of the image obtained from the HTS RF coil over a conventional Cu RF coil at room temperature was about 2.4-fold and 1.9-fold using the spin echo pulse sequence and gradient echo pulse sequence respectively.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.160-165
• /
• 2007

It is well recently recognized that quench is one of the serious problems for the integrity of superconducting magnets, which is mainly attribute to the rapid temperature rising in the magnet due to some extrinsic factors such as conductor motion, crack initiation etc. In order to apply acoustic emission(AE) technique effectively to monitor and diagnose superconducting magnets, it is essential to identify the sources of acoustic emission. In this paper, an acoustic emission technique has been used to monitor and diagnose quenching phenomenon in racetrack shaped superconducting magnets at cryogenic environment of 4.2K. For these purposes special attention was paid to detect AE signals associated with the quench of superconducting magnets. The characteristics of AE parameters have been analyzed by correlating with quench number, winding tension of superconducting coil and charge rate by transport current.