• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.266-270
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• 2014

In this paper, the effects of superconducting fault current limiter (SFCL) installed in power distribution system on reliability are evaluated and analyzed. The fault current will be decreased in power distribution system with SFCL because of the increased impedance of SFCL. The decreased fault current will improve the voltage drop of the bus of substation. The voltage drop is an important factor of power distribution system reliability. In this paper, improvement of reliability worth is analyzed when SFCLs are installed at the starting point in power distribution system. First, resistor-type SFCL model is used in PSCAD/EMTDC. Next, typical power distribution system is modeled. Finally, when the SFCLs with impedance 0.5 [${\Omega}$] are installed in feeder, power distribution system reliability is evaluated. Also, the improvement effect of reliability worth including the effect of voltage sag is analyzed using customer interruption cost according to whether or not SFCL is installed.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.34-39
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• 2018

A cryogenic cooling system is designed for a 154 kV/ 2 kA three-phase hybrid type superconducting fault current limiter (SFCL). The superconducting modules of the SFCL have the operating condition of 71 K at 500 kPa. The total heat load of the SFCL including the cooling system is estimated at 9.6 kW. The cooling system of the closed loop is configured to meet the operating condition, depending on cooling methods of forced flow cooling and re-liquefaction cooling. The cooling system is composed of three cryostats with superconducting modules, cryocoolers, liquid nitrogen circulation pumps, a subcooler and a pressure builder. The basic cooling concept is to circulate liquid nitrogen between three SFCL cryostats and the cryocooler, while maintaining the operating pressure. The design criterion for the cooling system is based on the operation results of the cooling system for a 154 kV/2 kA single-phase hybrid SFCL. The specifications of system components including the piping system are determined according to the design criterion.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.115-116
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• 2006

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 to limit fault current in power systems. The SFCLS, in contrast to current limiting reactors or high impedance transformers, are capable of limiting short circuit currents without adding considerable voltage drop and energy loss to power systems during normal operation. Under fault conditions, a resistance is automatically inserted into the power grid to limit the peak short-circuit current by transition from the superconducting state to the normal state, the quench. The advantages, like fail safe operation and quick recovery, make SFCL very attractive, especially for rapidly growing power systems with higher short-circuit capacities. In order to verify the effectiveness of the SFCL, in this paper, the analysis of fault current and voltage stability assessment in a sample distribution system and a transmission system are performed by the PSCAD/EMTDC based simulation method. Through the simulation, the advantage of SFCL application is shown, and the effective parameters of the SFCL are also recommended for both distribution and transmission systems. A resistive type component of SFCL is adopted in the analysis. The simulation results demonstrate not only the effectiveness of the proposed simulation scheme but also SFCL parameter assessment technique.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.19-23
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• 2021

We have studied the breaking system that combines a resistive superconducting fault current limiter (SFCL) and a DC circuit breaker for DC fault current. To verify the design of the 15 kV DC SFCL, which was driven from the previous work, a 500 V DC system was built and a scale-down SFCL were manufactured. The manufactured SFCL module was designed as a bifilar coil which is a structure that minimizes inductive reactance. The manufactured SFCL module has been experiment to verify characteristics of the current-limiting performance in the DC 500 V system. Also, the manufactured FCL module was combined with the DC circuit breaker to be experimented to analyze the breaking performance. As a result of the experiment, when SFCL was combined to the DC circuit breaker, the energy dissipation received by the DC circuit breaker was reduced by up to 84% compared to when the DC circuit breaker operates alone. We are preparing methods and experiments for the optimal method for much higher performance as a future work.

• 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.23 no.1
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• pp.42-47
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• 2010

The power burden of high-$T_c$ superconducting (HTSC) elements comprising superconducting fault current limiter (SFCL) using magnetic coupling of shunt reactors was analyzed. The magnetically coupled shunt reactors play a role in distributing the even power burden between HTSC elements comprising the SFCL, which contributes to the effective current limiting and recovery characteristics of the SFCL. It was confirmed through the comparative analysis on the SFCLs with both the magnetically coupled and the magnetically uncoupled shunt reactors that the magnetically coupled shunt reactors could improve the SFCL's performance by equalizing the power burden of HTSC elements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.26-30
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• 2008

The simulation and experiment for the fault current limiting characteristics of the superconducting fault current limiter (SFCL) using the magnetic coupling of series connected two coils were performed. The magnetic fluxes generated from two coils were canceled out during a normal time. However, the resistance generation of high-Tc superconducting (HTSC) element after a fault occurrence allows the magnetic fluxes of two coils and contributes to the fault current limiting operation. Through the computer simulation and the current limiting experiment for this SFCL, the operational current and the limiting impedance of the SFCL could be confirmed to be improved by adjusting the inductance ratio of two coils.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.101-102
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• 2006

We investigated the characteristics of flux-lock type superconducting fault current limiter (SFCL) by the fault cycles. Since the recovery characteristics of a superconducting element in the flux-lock type SFCL were dependent on the winding' direction between two coils, the analysis for the recovery characteristics of this type SFCL together with the current limiting characteristic is necessary to apply it to power system. As the fault cycles was increased from 1 cycle to 5 cycles, the initial limiting current ($I_{ini}$) and quench characteristic were mostly same. As the fault period increases, the recovery time of the superconducting element increases. The consumed energy and recovery characteristics in a superconducting element show the same tendency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.499-505
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• 2010

This paper analyzed that the coordination of recloser-fuse when a superconducting fault current limiter (SFCL) is installed to a power distribution system linked small scale cogeneration system. As a rule, the recloser to properly protect against both permanent and temporary fault is installed to upstream of fuse. Therefore, in a power distribution system linked small scale cogeneration system, the fault current is increased by adding fault current of small scale Cogeneration system when a permanent fault occurs, and the fuse could melt during the first fast operation of the recloser because of more sufficient heat from the increased current. However, when SFCLs are applied into a power distribution system linked small scale cogeneration system, the coordination of recloser-fuse could be accomplished due to decreased fault current as the effect of the impedance value of the SFCL. Therefore, to solve these problems, we analysed the operation of recloser-fuse coordination in a power distribution system linked small scale cogeneration system with SFCL using PSCAD/EMTDC.

• 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.