• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.213-213
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• 2009

In this paper, we investigated the current limiting characteristics due to the application location of the superconducting fault current limiter (SFCL) such as the feeder, the bus, the secondary side of transformer in a power distribution system. In addition, the quench and the recovery characteristics of the SFCL installed in each location of the power distribution system were compared each other. Through the analysis, in case that the SFCL was applied into the feeder line, its current limiting and voltage-drop compensating characteristics were confirmed to be the more effective. On the other hand, the power burden of the SFCL was increased higher compared to the SFCL'S other application location.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.281-283
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• 2008

The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.391-396
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• 2005

In this paper the modeling of interrupting characteristics of a high voltage current limiting fuse to be used in a power distribution system is introduced. In order to reduce the level of energy which can be absorbed by equipment during fault current flow, a high voltage current limiting fuse can generate a high voltage at the fuse terminals. Consequently it is necessary to model and analyze precisely the voltage and current variation during a CL fuse action. The characteristics of CL fuse operation modeled by electrical components have been performed with less than 6 [$\%$] errors. So the fuse designer or manufacturer can estimate the characteristics of CL fuse operation by using this modeling. The Electro Magnetic Transient Program (EMTP) is used to develop the modeling.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1661-1667
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• 2013

This paper studies the dynamic irreversible demagnetization characteristics of an interior permanent magnet (PM) brushless DC motor with a stator turn fault. A new algorithm, which is a finite element method (FEM) combined with a line voltage equation of the motor, is developed to analyze irreversible demagnetization under dynamic and transient states and considers a stator turn fault. The input current, circulating current, magnetic distribution characteristics, and operating property of the PM, including the irreversible demagnetization in the fault state, are analyzed using this algorithm by considering the magnetic saturation effect. The feasibility of the proposed method confirmed from the analysis results is verified via an experiment. Through this fault analysis, we can accurately check the fault phenomena of a PM motor against the demagnetization fault for fault prevention.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2078-2083
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• 2007

We have analyzed operating characteristics of transformer-type superconducting fault current limiter (SFCL) according to the serial or parallel connections of secondary coils with $YBa_2Cu_3O_7$ (YBCO) thin films. The turn ratio between the primary and secondary coils was 63:21. Transformer-type SFCL using a transformer with secondary winding of serial or parallel coils could reduce the unbalanced quench caused by differences of the critical current density between YBCO thin films. We found that transformer-type SFCL having serial or parallel connections induced simultaneous quench between the superconducting units. The limiting current in the transformer-type SFCL with a parallel connection was lowered to 30 % compared to the SFCL with a serial connection. In the meantime, when the currents generated in the superconducting units were similar, the voltage value in the parallel connection was 60 % as low as that in the serial connection. However, the voltage generated in the primary winding was some higher. In conclusion, we found that transformer-type SFCL with parallel connection of secondary coils was more effective in fault current limiting characteristics and in the reduction of the consumption power for superconducting units compared to those of the transformer-type SFCL with serial connection of secondary coils.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.368-369
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• 2011

This article suggests an online-based remote fault current mode discrimination method in order to identify the causes of the power line faults with various causes. For that, it refers to existing cause identification methods and categorizes modes by fault causes based on statistical techniques beforehand and performs the pretreatment process of fault currents by each cause acquired from the fault recorder into a topological plane in order to extract the characteristics of fault currents by each cause. After that, for the fault mode categorization, it discriminates modes by each cause using data by each cause as leaning data through utilizing RBF network based on FCM allowing self-organization in deciding the middle layer. And then it tests the validity of the suggested method as applying it to the data of the actual fault currents acquired from the fault recorder in the electric power transmission center.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.86-88
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• 2009

This article suggests an online-based remote fault current mode discrimination method in order to identify the causes of the power line faults with various causes. For that, it refers to existing cause identification methods and categorizes modes by fault causes based on statistical techniques beforehand and performs the pre-treatment process of fault currents by each cause acquired from the fault recorder into a phase space in order to extract the characteristics of fault currents by each cause. After that, for the fault mode categorization, it discriminates modes by each cause using data by each cause as leaning data through utilizing RBF network. And then it tests the validity of the suggested method as applying it to the data of the actual fault currents acquired from the fault recorder in the electric power transmission center.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.856-862
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• 2005

A flux-lock type SFCL consists of two coils, which are wound in parallel each other through an iron core, and a HTSC thin film connected in series with coil 2. If the current of the HTSC thin film exceeds its critical current by the fault accident, the resistance generated of the HTSC thin film, and thereby the fault current can be limited by the impedance of the flux-lock type SFCL. The amplitude of fault current can be set by the impedance of the flux-lock type SFCL. In this paper, we investigated the variance of the limiting current due to the ratio of inductances between coil 1 and coil 2 in the flux-lock type SFCL through the computer simulations and short circuit tests. In addition, both the simulation results and experimental ones were compared each other. From the comparison of both the results, the simulation results agreed well with the experimental ones.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.90-95
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• 2009

The application of a large power transformer into a power distribution system was inevitable due to the increase of power demand and distributed generation. However, the decrease of the power transformer‘s impedance causes the short-circuit current of the power distribution system to increase and thus, the higher short-circuit current exceeds the cut-off ratings of the protective devices such as a circuit breaker. To solve these problems, several countermeasures have been proposed to protect the power system effectively from the higher fault current and the superconducting fault current limiter (SFCL) has been expected to be the promising countermeasure. However, the current limiting effect of SFCL including its bus voltage drop compensation depends on SFCL's application location in a distributed power system. In this paper, the current limiting and the bus-voltage drop compensating characteristics of the SFCL applied into a power distribution system were studied. In addition, the quench and the recovery characteristics of the SFCLs in each location of the power distribution system were compared each other.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.381-382
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• 2008

This paper presents a novel scheme for reducing an asymmetry current with SFCL (Superconducting Fault Current Limiter) operation during transient period, when a fault occurs in power systems. The main idea is installation an auxiliary SFCL with characteristics, which reduces the asymmetry fault current in first half cycle before the operating of main SFCL. For proper activities of SFCLs, the principle of asymmetry current nature is reviewed. A scheme of asymmetry components reduction with SFCL is then explained. The EMTP/ATPDraw model of SFCLs using MODELS language developed and simulated to verify the performance and effectiveness.