• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.12
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• pp.1239-1245
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• 1990

With the rapid growth of power system capacity, fault current levels approach the maximum capacity of circuit breakers. In this paper, a superconducting current limiter (SCL) is proposed to reduce the fault current to an appropriate level. Superconductor for SCL has been examined and design criterion of each triggering method has been shown. Thin film SCL has been fabricated and switching characteristics are shown, where thermal and current triggering methods are adopted. Experimental result shows that fault current is reduced to one-half.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.878-882
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• 2016

These days, SFCLs are being developed in order to limit fault current. However, the superconducting elements that limit the fault current have such problems as capacity increase and require auxiliary devices including cooling device. If devices that comprise the current power network can withstand fault current for at least one cycle, it is possible to limit the fault current with current limiting elements by bypassing it on the fault line. In this study, the fault current limiter was configured with current transformer, vacuum interrupter, and current limiting element. Through the experience, it was confirmed that the fault current was limited within one cycle. The superconducting element, as a current limiting element, limited the fault current by 80 % within one cycle from fault occurrence, and the passive element limited it more than 95 %. Also, through the comparison between resistance curve and power consumption curve, it was confirmed that the current limiting element using a passive element was more stable than the superconducting element that required capacity increase and other auxiliary devices. It was considered that the FCL proposed in this study could limit fault current stably within one cycle from fault occurrence by using the existing power technologies such as fault current detection and solenoid valve operating circuit.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.777-781
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• 2014

The current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL) using series connected two coils with twice triggering operation, which consists of series connected two coils and two superconducting (SC) modules with the inserting resistance, was analyzed. The feature of the suggested SFCL is that it can limit the fault current by triggering either one SC module or two SC modules comprising the SFCL depending on the amplitude of the fault current. To verify the current limiting operation of the suggested SFCL, the short-circuits in the fault location with the different fault currents were tested and its useful operations were described through the analysis on the tested results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.344-345
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• 2009

The flux-coupling type superconducting fault current limiter(SFCL) is composed of a series transformer and superconducting unit of the YBCO coated conductor. The primary and secondary coils in the transformer were wound in series each other through an iron core and the YBCO coated conductor was connected with secondary coil in parallel. In a normal condition, the flux generated from a primary coil is cancelled out by its structure and the zero resistance of the YBCO thin films. When a fault occurs, the resistance of the YBCO coated conductor was generated and the fault current was limited by the SFCL. In this paper, we investigated the fault current limiting characteristics according to turn ratio in the flux-coupling type SFCL. The experiment results that the fault current limiting characteristics was improved according to turn ratio.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1817-1822
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• 2011

The fault current has been increasing due to expansive substation facilities for meeting the increase of demand. To limit increasing fault current in a power system, among methods the superconducting fault current limiter (SFCL) has been considered to be adopted in the power grid. However, in case of adopting SFCL in the power system, most of SFCLs need to solve problems such as recovery, cost. With efforts to solve those problems, the novel fault current limiting device which is called hybrid SFCL is developed. To apply the hybrid SFCL, it has to be needed to analyze application possibility and itself operation characteristics. In this paper, the fault current limiting and operation characteristics of hybrid SFCL with first half cycle the limiting operation in case of various resistances of superconducting element were analyzed through experiment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.370-374
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• 2005

AC loss of a superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in power systems. Therefore, the AC loss characteristics in several fault current limiting elements of a coil type have been investigated experimentally. The test result shows that AC losses measured in the fault current limiting elements depend on arrangement of a voltage lead. The AC loss of a bifilar coil is smallest among the fault current limiting elements of the coil type. The measured AC loss of the bifilar coil is much smaller than that calculated from Norris's elliptical model. However, the loss measured in a meander, which is frequently used in a resistive fault current limiter, agrees well to the theoretical one.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.592-593
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• 2015

Recently, the fault current has increased to exceed the rated breaking capacity of protective device due to the growth of the power demand on the power system where is changed into the loop-, mesh-, network grid. To limit fault current, the superconducting fault current limiter (SFCL) is announced with various methods. In many researches, the current limiting effect with the SFCL has been analyzed considering the rated breaking capacity of the CB with one fault condition. However, the power system has various short circuit and operation conditions. In order to select the capacity of the SFCL with reclosing operation and burden of the fault current on the protective device, the characteristics of the power system were investigated. Through the analysis, the evaluation method of the current rate was improved.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1540-1541
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• 2006

For limitation and interruption of short circuit currents from low voltage to extra high voltage applications, the electrical equipment including fuses and circuit breakers, are widely used today. But in order to anticipate increasing needs for effective and competitive device for limiting the growing fault current in electrical power systems, fault current limitation technologies and fault current limitation devices are widely introduced and investigated in these days. Fault current limiters are emerging electric equipment which is under development using various methods including superconducting fault current limiter, solid state fault current limiter, arc driving fault current limiters. And these various methods have some advantages and disadvantages to take into considerations In order to commercialize fault current limiters in the electrical networks, a lot of discussions should be given on the point that fault current limiting methods, need for fault current limiters, coordination with existing protective system, and field experience before commercialization. In this paper, recent trends of fault current limiting technologies will be reviewed and the key issues of superconducting fault current limiters will be dealt with. And finally, future applications of superconducting fault current limiters would be discussed.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.17-20
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• 2005

AC loss of a high $T_c$ superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in the power systems. Therefore, several samples of the fault current limiting coils have been fabricated and the effect of conductor's arrangement and current direction on AC loss characteristics investigated experimentally The test result shows that the AC losses measured in the fault current limiting coils depend significantly on the conductor's arrangement. Futhermore, they are also considerably influenced by the conductor's current direction. The AC loss measured in the face-to-face arrangement is smallest among the fault current limiting coil samples.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.56-62
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• 2014

When fault currents contain decaying DC offset, the peak value of the fault current in the first cycle of the fault period is higher than the fault current during the steady-state period. To reduce the asymmetric fault current, this paper proposes an operation scheme using the series connection of two hybrid type Superconducting Fault Current Limiters (SFCLs) : an auxiliary SFCL and a main SFCL. The proposed method calculates the fault angle by comparing the zero-crossing time with fault detection time. According to the fault angle calculated, an auxiliary SFCL operates to reduce an asymmetric fault current during half a cycle after fault occurrence. After this process, the fault current is limited by a main SFCL. To confirm the usefulness of the proposed method, case studies using Electro-Magnetic Transients Program (EMTP)/Alternative Transient Program (ATP) Draw are perfomed.