• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.523-526
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• 2004

According to the continuous demand for power and the growth of electric power utilities, the electric power transmission capacity was increased. The increase of the electric power transmission capacity results in an increase of the fault current level a fault happened. So the superconducting fault current limiter(SFCL) has been reached as the countermeasure for the reduction of the fault current. In this paper, we investigate the fault currents characteristics of resistive type SFCL according to fault angles when AC power source applied. As the fault angles increase, the first peak value of fault current decreased lower. On the other hand, the power burden of SFCL increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.159-163
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• 2010

The superconducting fault current limiter (SFCL) plays a role in compensating the voltage sag of the sound feeder adjacent to the fault feeder as well as the fault current limiting operation of the fault feeder. Especially, the SFCL using magnetic coupling of two coils with parallel connection has different voltage sag compensating and current limiting characteristics due to the winding direction and the inductance ratio of two coils. In this paper, the current limiting and the voltage sag compensating characteristics of a SFCL using magnetic coupling of parallel connected two coils were analyzed. Through the analysis on the experimental results considering the winding direction of two coils, the SFCL designed with the additive polarity winding was shown to have the higher limited fault current than the SFCL designed with the subtractive polarity winding. In addition, it could be confirmed that the higher fault current limitation of the SFCL could be contributed to the higher load voltage sag compensation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.522-525
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• 2009

We investigated the fault current characteristics of the separates three-phase flux-lock type superconducting fault current limiter(SFCL) according to the variation of inductances. The single-phase flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil on an iron core. And superconductor is series connected on secondary coil. Superconductor is using the YBCO coated conductor. The separated three-phase flux-lock type SFCL consists of single-phase flux-phase type SFCL in each phase. To analyze the current limiting characteristics of a three-phase flux-lock type SFCL, the short circuit experiments were carried out fault such as the triple line-to-ground fault. The experimental result shows that fault current limiting characteristics of additive polarity winding was better than subtractive polarity winding and when the inductances of coil 2 was lower, resistances of YBCO CC was more generated.

• Journal of Power Electronics
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• v.12 no.1
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• pp.10-18
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• 2012

This paper proposes a finite element method (FEM)-based model of an interior permanent magnet (IPM)-type BLDC motor having stator inter-turn faults. We also propose impedance modeling of the magnetic characteristics. By integrating the developed model with a current-controlled voltage source inverter (CCVSI) model, the distributed characteristics of an inter-turn fault operated by a six-switch inverter are investigated considering speed control. Moreover, this paper presents the flux density distribution and torque characteristics for analyzing the inter-turn fault of an IPM-type BLDC motor. Additionally, fault impedance is required to calculate the circulating current that causes magnetic distortion. Thus, this paper proposes a method for estimating the circulating current taking into account the voltage at the shorted turn and the rotating speed. The analysis data were verified experimentally.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.522-532
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• 2017

In this study, we propose a fault analysis method for a power distribution grid with PCS-based DERs. We first explain the characteristics of a PCS-based DER. According to the characteristics, the DER is considered as a current-controlled voltage source, which produces varying voltages within a certain limit so that currents equal to given references flowing from the DER to the grid (currents controlled). So, we introduce the symmetrical equivalent models in the form of varying voltage source for fault analysis and then, construct a convex optimization problem to solve the fault problem associated with the equivalent models and grid conditions. Thus, the proposed method enables to perform a proper fault analysis considering the characteristics of the DER, which are currents controlled, voltage limited, and unity power factor achievement. To verify the validity of the proposed method, we perform computer simulations with the proposed method and with MATLAB Simulink, and the results are compared.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.213-216
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• 2007

The computer simulation for the fault current limiting characteristics of the superconducting fault current limiter (SFCL) using the magnetic coupling of two coils was performed. The magnetic fluxes generated from two coils were canceled out during a normal time. However, the resistance generation of high-$T_c$ superconducting (HTSC) element after a fault occurrence keeps up the magnetic fluxes of two coils and contributes to the fault current limiting operation. Through the computer simulation for the fault current limiting characteristics based on its electrical equivalent circuit, its operational current and the limiting impedance could be improved by adjusting the inductance ratio between two coils.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.21-22
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• 2008

The increase of fault current due to larger power demand has caused the capacity of power machines in grid to increase. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) have proposed one of several countermeasures. Therefore, to introduce SFCL into power distribution system, the position of SFCL in power distribution system is selected among some cases. Each position changes fault current limiting characteristics and SFCL's requirement. In this paper, the characteristics of limiting fault current according to installed SFCL's location in power distribution system.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.114-116
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• 1994

Recently a superconducting fault current limiter(SFCL) has public attentions for the solution of large fault currents of power systems. Though a SFCL has more effective characteristics than the other current limiting devices, there are many problems to apply it to real power systems. For the analysis of transient fault characteristics of the SFCL, we designed and fabricated a inductive SFCL and tested it in 35V line. The superconducting cable of the SFCL was quenched at lower current(49A) than the designed critical current but it limited the fault current to the lower value(150A) than the one expected without SFCL(250A). And within one period the fault current decreased lower than normal laod current.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.131-133
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• 1995

Inductive high-Tc superconducting fault current limiter using YBCO superconducting ring in the secondary part has many advantages in power networks. It is based on the superconducting to normal transition and this paper describes its operational characteristics and experimental results, especially focused on the harmonic component analysis and recovery time. We fabricated and tested it under various conditions for the analysis of transient fault characteristics. And for the analysis of harmonics we used FFT methods. The superconducting ring was quenched in 240Arms and fault current was effectively limited to the lower current level. In addition, it was fast recovered when the fault condition was removed and after fault the system had odd harmonics.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.368-370
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• 2005

Superconducting fault current limiter (SFCL) provides the effect such as enhancement in power system reliability due to limiting fault current in a few miliseconds. The flux-lock type SFCL among various type SFCLs consists of two coils wound on the same iron core and a component using the YBCO thin film. In the SFCL, operation characteristics can be controlled by adjusting the inductances and the winding directions of the coils. In this paper, we investigated the various fault current limiting characteristics according to the voltage level. To analyze the current limiting performance, we compared operational characteristics on the subtractive polarity winding direction on in case of open-loop iron core.