• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.371-371
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• 2009

For the application of superconducting wires to fault current limiting devices, it is required that they have a high rated voltage when a fault occurs. Stabilizer-free coated conductors, particularly, shows a good performance for the high rated voltage, which is beyond 0.6 V/cm. In this study, using the stabilizer-free coated conductors, we made fault current limiting devices and examined their characteristics. Fault current limiting devices were fabricated with a shape of the cylinder of a mono-filar coil winding. Stabilizer-free coated conductors were wound along the mono-filar coil line and the terminal parts between the wire and metal were soldered using In solder. Two kinds of devices were fabricated by a different method in the terminal joint, one was made by a soldering and the other was made by a soldering-free joint. Critical currents and resistance at the joint parts were measured. In addition, long-time current flowing tests were also carried out for the characterization of the fault current limiting devices.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.619-623
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• 2004

We proposed the bridge type superconducting fault current limiter(SFCL) using switching operation of high-Tc superconducting(HTSC) thin film. The proposed bridge type SFCL consists of HTSC thin film, a diode bridge and a dc reactor. The controller for the operation of an interrupter is required in the conventional bridge type SFCL to prevent the continuous increase of fault current after a fault happens. On the other hand, the proposed bridge type SFCL can limit the fault current without the interrupter and the controller for its operation by the resistance generated when the gradually increased fault current exceeds HTSC thin film's critical current. We calculated the time when the gradually increased fault current started to be limited by the resistance generated in HTSC thin film after a fault happened and confirmed that it could be dependent on the amplitude of source voltage. The experimental results well agreed with the calculated ones from simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1944-1947
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• 2012

In this work, we investigated quench characteristics of matrix-type superconducting fault current limiters (MFCLs) according to the turn number of reactors. The reactors used in MFCLs apply magnetic field to superconducting elements within reactors when fault currents surge into MFCL systems. It makes the fast and simultaneous quenches between superconducting elements. Also reactors decrease the fault power burden of superconducting elements by bypassing the partial fault currents to itself, when quench occurs. These structure proposed in this work can be expected to achieve much more current limiting capacity even though it uses less superconductors compared with other type SFCLs. Three reactors were made by Bakelite. These reactors with the turn number of 190, 380 and 570, had the length of 270 mm and diameter of 80 mm. We reported experimental results, including fault currents, fault voltages and resistance in superconducting elements according to the turn number of reactors. We confirmed that experimental results will be useful in next future plan for the real power grid.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.24-26
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• 1995

In this paper, we investigated transient fault currents in a magnetic coupling High-Tc superconducting current limiter(HCL). It has an important effect on the reliability and stability of the power system. In order to analyze transient fault characteristics of HCL, we fabricated a magnetic coupling HCL and tested it in different fault conditions. An important parameter of design and manufacture which makes HCL inherently reliable is reduction of inrush fault currents. Without inrush fault currents, the currents flowing under such conditions can be limited to a desired-value within one cycle. Inrush fault current depends on saturation, normal spot propagation velocity, turns ratio and the fault angle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.524-530
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• 2011

This paper analyzes fault tolerance under a stator turn fault, according to the winding configuration. Improvement of torque characteristics and fault tolerance can be achieved by winding configuration without additional methods. And, torque characteristics and fault tolerance according to the winding configuration can be usually analyzed by analytical method. But, when the stator turn fault generates, compare to the steady-state, analysis of torque characteristics and fault tolerance using the analytical method is not accurate because it does not reflect influence in mutual inductance and magnetic non-linearity. Therefore, analysis of torque characteristics and fault tolerance has to be performed by using the numerical method under fault condition. This paper develops fault characteristics according to the winding configuration using the FEM-base model considered magnetic non-linearity. And, this paper suggests fault tolerance improvement according to the winding configuration, by the comparison of 8/12 and 10/12 models, under fault condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1855-1860
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• 2009

This paper caused a distribution utility to generation of analysis fault several cases on the ground of substation in a energy meter three phase current, voltage data measurement to fault type and characteristics. Mother wavelet transformation of suitable to method algorithm from the distribution utility to generation of fault in image impedance etc several parameter for utility characteristics effective to probatory fault point extraction.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.93-96
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• 2004

In this paper, we analyzed the current limiting characteristics according to increase of source voltage in the flux-lock type high-Tc superconducting fault current limiter (SFCL). The flux-lock type SFCL consisted of two coils, which were wound in parallel each other through an iron core, and high-Tc superconducting (HTSC) element connected with coil 2 in series. The flux-lock type SFCL has the characteristics better in comparison with the resistive type SFCL because the fault current in the flux-lock type SFCL can be divided into two coils by the inductance ratio of coil 1 and coil 2. The fault current limiting operation of the flux-lock type SFCL can be different due to winding direction of the two coils. The winding method where the decrease of linkage flux between two coils in the accident happens is called the subtractive polarity winding and the winding method in case of the increase of linkage flux is called the additive polarity winding. The fault current limiting experiments according to the source voltage were performed for these two winding methods. Through the comparison and the analysis of the experimental data, we confirmed that the quench time was shorter, irrespective of the winding direction as the source voltage increased and that the fault current and the HTSC's resistance increased as the amplitude of the source voltage increased. The additive polarity winding made the fast quench time and the lower resistance of HTSC element in comparison with the subtractive polarity winding. The fault current of the subtractive polarity winding was larger than that of the additive polarity winding. In conclusion, we found that the additive polarity winding reduced the burden of SFCL because the quench time was shorter and the fault current was smaller than those of the subtractive polarity winding.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.46-51
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• 2007

The fault current limiting characteristics of superconducting fault current limiter(SFCL) using magnetic coupling of two coils were investigated. This SFCL consists of a high-TC superconducting(HTSC) element and two coils with series or parallel connection on the same iron. In normal time, the inner magnetic fluxes generated by two coils are canceled in case that the HTSC element keeps superconducting state. However, in case that the resistance of the HTSC element happens by a short-circuit the magnetic fluxes, not cancelled, induce the voltages across two coils and the fault current can be limited by the impedance of this SFCL. This SFCL has the merit that the operational current of SFCL can be increased higher than the critical current of the superconducting element by adjusting the inductance ratio between two coils. To confirm its operation, the circuit for the fault simulation was constructed. From the measured voltage and current of the SFCL, it was confirmed that the operating current of this SFCL increased more than that of HTSC element's independent operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.159-160
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• 2005

The superconducting fault current limiter(SFCLs) provides the effect such as enhancement in the power system reliability due to limiting fault current in a few miliseconds. The Flux-lock type SFCL using the YBCO film among various type SFCLs consists of the primary and the secondary copper coils that are wound in parallel each other through the iron core. The operation can be controlled by adjusting the inductances and the winging directions of each the coil. We compared the current limiting performance on the additive and the subtractive polarity winding directions in case of an open-loop iron core. To analyze quench characteristics, we experimented various phase angle.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.285-290
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• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.