• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.760-761
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• 2001

We have studied quench characteristics for current limiting elements of YBCO films in applied fields of 0 - 130 mT. The films were deposited on sapphire substrates and covered by gold top layer. The current limiting element consists of 2 mm wide YBCO stripes connected in series. The electric field - current density (E-J) measurements showed that the presence of applied magnetic fields induces uniform quench distribution for the stripes, otherwise non-uniform quenches were observed. We suggest that suppressing the critical current by increased fields due to fault current effectively forced the stripes of higher Jc(0) to quench, resulting in equalizing quench times.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.51-54
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• 2021

The DC system has less power loss compared to the AC system because there is no influence of frequency and dielectric loss. However, the zero-crossing point of the current is not detected in the event of a short circuit fault, and it is difficult to interruption due to the large fault current that occurs during the opening, so the reliability of the DC breaker is required. As a solution to this, an LC resonance DC circuit breaker combined a superconducting element has been proposed. This is a method of limiting the fault current, which rises rapidly in case of a short circuit fault, with the quench resistance of the superconducting element, and interruption the fault current passing through the zero-crossing point through LC resonance. The superconducting current limiting element combined to the DC circuit breaker plays an important role in reducing the electrical burden of the circuit breaker. However, at the beginning of a short circuit fault, superconducting devices also have a large electrical burden due to large fault currents, which can destroy the element. In this paper, the reactor is connected to the source side of the circuit using PSCAD/EMTDC. After that, the change of the fault current according to the reactor capacity and the electrical burden of the superconducting element were confirmed through simulation. As a result, it was confirmed that the interruption time was delayed as the capacity of the reactor connected to the source side increased, but peak of the fault current decreased, the zero-crossing point generation time was shortened, and the electrical burden of the superconducting element decreased.

• 조명전기설비학회논문지
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• 제28권8호
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• pp.62-68
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• 2014

The series connection type superconducting fault current limiter (SFCL) with added third winding, which was magnetically coupled in one iron core, was proposed. The proposed SFCL was expected to be more improved by just adding third winding into the conventional series connection type SFCL with two coils. To analyze the contribution of the third winding for the current limiting and the recovery characteristics of the SFCL, the short-circuit tests for the series connection type SFCL with the added third winding were performed together with the analysis on its electrical equivalent circuit. From the comparative analysis on the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising this SFCL, the improved current limiting and recovery characteristics of the series connection type SFCL using the third winding could be confirmed.

• 조명전기설비학회논문지
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• 제21권10호
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• pp.46-51
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• 2007

본 논문에서는 두 코일의 직 병렬결합을 이용한 초전도 사고전류제한기의 사고전류제한 특성을 분석하였다. 구조는 병렬 또는 직렬로 연결된 두 코일과 두 코일 중 하나와 직렬 또는 병렬로 연결되는 초전도 소자로 구성된다. 동작원리는 사고전에는 초전도 소자는 초전도 상태에 있어 병렬 또는 직렬로 연결된 두 코일에 의해 발생되는 자속은 서로 상쇄되어 두 코일에 유기되는 전압이 제로를 유지하게 되지만 사고가 발생할 경우 초전도 소자의 저항이 발생되어 두 코일에서 발생되는 자속은 더 이상 상쇄되지 않게 된다. 따라서 두 코일에 전압이 유기되고 이에 따라 사고전류를 제한하게 된다. 단락실험을 통해 두 코일의 직 병렬결합에 따른 사고전류제한 특성을 분석하였으며 분석을 동해 사고전류제한기의 동작전류를 증가시킬 수 있음을 확인하였다.

• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.363-369
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• 2005

we compared the operating characteristics between flux-lock type and resistive type superconducting fault current limiters(SFCLs). Flux-lock type SFCL consists of two coils, which are wound in parallel each other through an iron core, and a high-Tc superconducting(HTSC) element is connected with coil 2 in series. The the flux-lock type SFCL can be divided into the subtractive polarity winding and the additive polarity winding operations according to the winding directions between the coil 1 and coil 2. It was confirmed from experiments that flux-lock type SFCL could improve both the quench characteristics and the transport capacity compared to the resistive type SFCL, which means, the independent operation of HTSC element.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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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.

• 전기학회논문지P
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• 제59권3호
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• pp.330-334
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• 2010

We tried to combine a transformer with a superconducting element and investigated the current limiting characteristics. When a superconducting element was connected to third winding of the transformer, the fault current was limited to about 90 % effectively. The fault current and consumption power were able to be controlled by the turn's ratio of secondary and third windings. It gives flexibility of the rating of a transformer in the power grid. As a result, power burden of a superconducting element was reduced by the decrease of turn's ratio in third winding of a transformer. It was because the voltage behavior of a superconducting element was dependent on turn's ratio of a transformer while the current characteristic was independent.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.285-290
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• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.

• 전기학회논문지
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• 제60권10호
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• pp.1832-1837
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• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• 조명전기설비학회논문지
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• 제22권1호
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• pp.113-117
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• 2008

본 논문에서는 결선방향에 따른 자속구속형 전류제한기의 전류제한 및 회 특성에 대해 분석하였다. 자속구속형 초전도 한류기는 초전도 소자와 직렬로 연결된 2차 권선과 병렬로 연결된 1 2차 권선으로 구성되어 있다. 1 2차 권선의 결선방향에 따른 가극 결선과 가극 결선을 갖는 자속구속형 전류제한기를 저항형 전류제한기와 비교하여 분석하였다. 전류제한 및 회복특성은 1 2차 권선의 결선방향에 의존한다. 가극 결선을 갖는 자속구속형 전류제한기의 퀜치시간은 감극 결선이나 저항형 전류제한기보다 더 빠르다는 것을 확인하였다. 초전도 소자에서 소비되는 에너지는 $W= VIt=I^2Rt$으로 표현할 수 있다. 결선 방향에 따라 초전도 소자에서 소비되는 에너지의 차이는 초전도 소자에서 부담하는 전압의 차이 때문이라는 것을 확인할 수 있었다.