• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.25-31
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• 2005

Since the discovery of the high temperature superconductors many researches have been performed for the practical applications of superconductivity technologies in various fields. As results, significant progress has been achieved. Especially, Superconducting Fault Current Limiter (SFCL) offers an attractive means In limit fault current in power systems. HTS resistive type SFCL is based on the ultra fast transition from the superconducting (non resistive) state to the normal (resistive) state by overstepping the critical current density, In this study, the simulation method of resistive type superconducting fault current limiter using EMTDC is proposed and the developed EMTDC model of SFCL is applied to the modeled power network using the Parameters of real system.

• Superconductivity and Cryogenics
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• v.5 no.1
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• pp.10-17
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• 2003

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. Furthermore, the applications of high temperature superconducting materials (HTSC) into the current limiting devices are new approach for developing of novel and effective col-rent limitation electrical equipment. In this research, the necessities of current limitation technology and the developed and developing current limitation devices for power systems are introduced. Finally, the investigation of resistive type fault current limiters which is under development by LG and KEPCO were introduced.

• Progress in Superconductivity and Cryogenics
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• v.10 no.2
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• pp.30-33
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• 2008

Several kinds of superconducting fault current limiters (SFCLs), which reduces huge fault current, have been developing by many research groups. The SFCL has no impedance during normal operation, so it dose not give any influence to electric power system. The resistive type SFCL reduces the fault current with the impedance generated in the superconducting part of the SFCL when the fault current exceeds the critical current of SFCL. In this paper, a new type resistive SFCL made of bifilar coil wound with two different high-Tc superconducting (HTS) wires in parallel. Although a bifilar coil has theoretically no inductance, the bifilar coil made in this paper could generate inductance at fault. The specifications of the used two wires were considerably different, thus current distribution between the two HTS wire was different at fault. When the fault current exceeded the critical current of one wire in the bifilar coil, the momentary sharp increase of impedance was detected. Base on the results, a new resistive type SFCL can generate not only resistance but also inductance, which can be used to control a fault current in the future.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.9-13
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• 2007

Coated conductor(CC) is recently in actively progress for the research and development, and its can be used various stabilizer lot the specific requirements for each application. Among various superconducting applications, coated conductor applied to superconducting fault current limiters(SFCLS) bypasses fault current to its stabilizer, where the surge is abruptly reduced ; thus, stainless steel, which has large resistivity can be a suitable stabilizer for SFCLS. Despite high n-value of the YBCO, CC stabilized with stainless steel did not effectively limit the first peak fault current. In the short circuit test results of AMSC's 344S, a half period delay was observed between the fault and the generation of resistance(60Hz). In this paper, we performed short-circuit experiments with stacked and unstacked CC and compared the test results to analyze effective fault current limiting characteristics. we compared time of the generated resistance as the fault current limiting characteristics and made the samples one is the stacked CC and the other is unstacked CC. These samples were used equal numbers of pieces of CC. In addition, comparison and analysis was made for the stacked structure by measuring fault current limiting characteristics with respect to thermal insulation by impregnating with epoxy resin.

• Proceedings of the KIEE Conference
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• summer
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• pp.409-411
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• 2004

The need for Fault Current Limiters (FCL) is associated with the continuous growth and interconnection of modem power systems and increase in dispersed generation facilities, which result in progressive increase in the short circuit capacity far beyond their original design capacity. Fault Current Limiters (FCL) clips the fault currents and reduces the electromechanical stresses on the network and the need to handle excessive fault currents. In addition, the reduction of the fault duration Provided by the limiter should increase the power transmission capability and improve the dynamic stability. This paper proposes the model of resistive type superconducting fault current limiter using EMTDC(Electromagnetic transients for DC analysis program). In order to verify the effectiveness of the SFCL, in this paper, the analysis of fault current in a transmission system through the EMTDC based simulation by using the modeled component of a resistive type SFCL is peformed and the detailed results are given.

• 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.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.289-293
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• 2007

The fault current limiting characteristics of the separated and the integrated three-phase flux-lock type superconducting fault current limiters (SFCLs) were analyzed. The three-phase flux-lock type SFCL consisted of three flux-lock reactors and three $high-T_c$ superconducting (HTSC) elements. In the integrated three-phase flux-lock type SFCL, three flux-lock reactors are connected on the same iron core. On the other hand, three flux-lock reactors of the separated three-phase flux-lock type SFCL are connected on three separated iron cores. The integrated three-phase flux-lock type SFCL showed the different fault current limiting characteristics from the separated three-phase flux-lock type SFCL that the fault phase could affect the sound phase, which resulted in quench of the HTSC element in the sound phase. Through the computer simulation applying numerical analysis for its three-phase equivalent circuit, the fault current limiting characteristics of the separated and the integrated three-phase flux-lock type SFCLs according to the ground fault types were compared.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.176-177
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• 2001

Three nearly identical superconducting fault current limiters (SFCLs) were connected in series to increase the voltage ratings. A slight difference in the quench starting point of individual SFCL units produced significantly imbalanced power distribution when connected in series. The imbalance was successfully removed by connecting a shunt resistor to one SFCL in parallel. 1.2 kV SFCL was designed with five current limiting elements and two or three shunt resistors.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.737-741
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• 2000

We fabricated resistive superconducting fault current limiters (SFCL) based on YBCO thin films grown on 2-inch diameter $Al_2O_3$ substrates. Two SFCLs with nearly identical properties were connected in series to investigate simultaneous quench. There was a slight difference in the rate of voltage increase between two SFCL units when they were operated independently. This difference resulted in significantly imbalanced power dissipation between the units. This imbalance was removed by connecting a shunt resister to an SFCL in parallel. The appropriate values of shunt resistance were 80 ${\Omega}$ at 75 $V_rms$ and 110 ${\Omega}$ at 120 $V_rms$, respectively. Increased power input at high voltages also reduced the initial imbalance in power dissipation, but with increase in film temperature to higher than 200 K.

• 한국초전도학회:학술대회논문집
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• v.11
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• pp.66-66
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• 2001