• 전기학회논문지
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• 제60권6호
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• pp.1268-1273
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• 2011

The study on power capacity increase of superconducting fault current limiter (SFCL) is one of the most important researches to apply a SFCL in the power system. To achieve this, we thought that the unbalanced quenching problem generated in series connection of superconducting units should be solved. In this paper, we investigated the quenching characteristics of superconducting units in the transformer-type SFCL with or without the neutral line between secondary windings and superconducting units. In case of transformer-type SFCL without neutral line, the connection structure of superconducting units is identical to that of the resistive-type SFCL connected in series. Therefore, the unbalanced quenching was occurred by difference of critical current between superconducting units. However, in case of transformer-type SFCL with neutral line, the superconducting units with different critical current were simultaneously quenched. It was because the currents induced by secondary winding were separately flowed through the superconducting units. By these results, we confirmed that the resistances and consumption powers of the superconducting units were equally generated.

• 한국전기전자재료학회논문지
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• 제35권2호
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• pp.184-189
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• 2022

In this paper, the fault current limiting operations of three-phase transformer type superconducting fault current limiter (SFCL) using double quench, which consisted of E-I iron core with three legs wound by primary and secondary windings and two superconducting modules (SCMs), were analyzed according to three-phase ground fault types. To verify the effective operation of the three-phase transformer type SFCL using double quench, the test circuit for three-phase ground faults was constructed, and the fault current tests were carried out. Through analysis on the fault current test results, the different fault current limiting characteristics of three-phase transformer type SFCL using double quench from three-phase transformer type SFCL using three SCMs were discussed.

• 한국전기전자재료학회논문지
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• 제25권12호
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• pp.1000-1003
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• 2012

The superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes and 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 flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, has different voltage sag compensating and current limiting characteristics due to the winding direction and the inductance ratio of two coils. The current limiting and the voltage sag compensating characteristics of a SFCL using a transformer winding were analyzed. Through the analysis on the short-circuit tests results considering the winding direction of two coils, the SFCL designed with the additive polarity winding has shown the higher limited fault current than the SFCL designed with the subtractive polarity winding. It could be confirmed that the higher fault current limitation of the SFCL could be contributed to the higher load voltage sag compensation.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.44-47
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• 2017

In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.2090-2091
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• 2007

We investigated the characteristics of transformer type SFCL with neutral line. The transformer type SFCL having neutral line has achieved the simultaneous quench because the secondary winding has acted as parallel reactor. The fault current of SFCL was limited according to ratio of turn number between primary and secondary windings. Therefore, the power burden of superconducting element can be reduced by reduction of ratio of turn number between primary and secondary windings. As a result, we could expect reduction of it's volume in the transformer type SFCL.

• Transactions on Electrical and Electronic Materials
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• 제18권1호
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• pp.42-45
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• 2017

In this paper, a transformer type SFCL (superconducting fault current limiter) using an additional magnetically coupled circuit was suggested. Its transient fault current limiting characteristics, due to the winding direction of additional coupled circuit, were analyzed through fault current limiting tests. The suggested transformer type SFCL was composed of the primary winding, and one secondary winding wound on the same iron core together with an additional magnetically coupled circuit. That circuit consists of the other secondary winding together with the other SC (superconducting) element connected in parallel with its other secondary winding. As one of the effective design parameters to affect the transient fault current of the SFCL, the fault current limiting tests of the suggested SFCL were carried out considering the winding direction of its additional coupled circuit. It was confirmed that, through the analysis on the fault current tests of the SFCL, the quench sequence of two SC elements comprising the suggested SFCL could be adjusted by the winding direction of the additional coupled circuit.

• 전기학회논문지
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• 제60권7호
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• pp.1438-1443
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• 2011

The increase of power capacity in the superconducting fault current limiter (SFCL) is essential for application into the power grid. To achieve this, when superconducting units were connected in series and parallel, the unbalanced quenching characteristics between superconducting units generated by different critical current behavior should be improved. In the transformer-type SFCL, the superconducting units connected in series could be simultaneously quenched by the connection of neutral lines between secondary coils and superconducting units. From this the consumed power in superconducting units was equally distributed. In addition, the more the turn ratio of the transformer was reduced, the more consumed power in the superconducting units was reduced by the decrease of the induction voltage generated in the superconducting units. From those results, the transformer-type SFCL using neutral lines could increase the power capacity of the SFCL by the equal power division into the superconducting units.

• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.630-634
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• 2016

In this paper, we analyzed the power consumption and the accumulated energy in HTSC (high-TC superconducting elements) according to the resistance of HTSC element and the winding current of transformer type SFCL (superconducting fault current limiter) using double quench. For the analysis, two different inductances of the one secondary winding among two secondary windings comprising the transformer type SFCL were selected and the short-circuit tests were carried out. The consumed power and the accumulated energy in HTSC element connected into the secondary winding with larger inductance were analyzed to be larger compared to the one connected into the secondary winding with lower inductance.

• 한국초전도ㆍ저온공학회논문지
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• 제15권4호
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• pp.30-33
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• 2013

The studies of superconducting fault current limiter (SFCL) for reduction of the fault current are actively underway in the worldwide. In this paper, we analyzed the characteristics of a new type SFCL using the conventional transformer and superconducting elements combined mutually. The secondary and third windings of this SFCL were connected the load and the superconducting element, respectively. The electric power was provided to load connected to secondary windings of the transformer in normal state of power system. On the other hand, when the fault occurred in power system, the fault current was limited by closing the line of third winding of the transformer. At this time, the ripple phenomenon of the fault was minimized by opening the fault line in secondary winding of a transformer in power system. The sensing of the fault state was performed by the CT(current transformer) and then turn-on and turn-off switching behavior of the SFCL was performed by the SCR(silicon-controlled rectifier). As a result, the proposed SFCL limited the fault current within a half-cycle efficiently. We confirmed that the fault current limitation rate was changed according to the winding ratio of a transformer.

• 한국전기전자재료학회논문지
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• 제29권8호
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• pp.499-504
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• 2016

In this paper, we analyzed the operational characteristics of the fault current limiting according to the amplitude of the fault current for the transformer type superconducting fault current limiter (SFCL). If the fault current happens, the superconducting element connected to the secondary coil is occurred quench and the fault current is limited. When the larger fault current occurs, the superconducting element connected to the third coil is occurred additional quench and the peak fault current is limited. We found that the fault current can be more effectively controlled through the analysis of the fault current limiting and the short-circuit tests.