• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.85-86
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• 2008

This paper analyzes the improvement of the power quality by the reduction of the inrush current. We analyze the existing methods and simulate the segragated point-on-wave closing method selected as the proper method. And we attempts to use the resistive type Superconducting Fault Current Limiter(SFCL) to reduce the transformer inrush current. We simulate the various insertion resistances and analyze the voltage drop. All simulation are performed by EMTP. The simulation results show the validity and effectiveness of a SFCL application and the segragated point-on-wave closing method to reduce the inrush current and improve the power quality.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1531-1533
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• 1998

In this paper, the characteristics of the shielded inductive superconducting fault current limiter was designed and simulated. Parameters of design for superconducting tube, core and primary coil were first determined. And then according to the system characteristics such as load resistance, fault angle and source voltage, the simple power system composed of shielded inductive FCL was simulated by computer-aided numerical analysis. The flowing currents under the fault condition can be limited to about 10 A.

• 조명전기설비학회논문지
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• 제20권7호
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• pp.38-45
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• 2006

초전도전류제한기(SFCL)는 전력계통내 적용시 계통보호를 보다 향상시킬 수 있는 방안으로써 수초이내에 신속하게 사고전류를 제한한다. 이러한 SFCL중 자속구속형 전류제한기의 설계구조는 자속구속리액터인 하나의 철심에 1차측과 2차측 코일이 병렬로 결선되어 있다. 또한 전류제한소자인 YBCO박막과 2차측 코일을 직렬로 결선하여 설치장소의 조건에 따라 인덕턴스와 2차측 코일의 극성방향으로 과도전류 크기를 조절할 수 있다. 이러한 동작특성은 철심을 자속매개체로 적용되기 때문에 철심조건에 따른 성능평가실험은 필수적이다. 가극결선에서 전원전압을 200[Vrms] 인가시 피크전류는 폐루프가 30.71[A], 개루프가 32.01[A]까지 상승됨에 따라 초기과도 응답특성은 폐루프가 유리하였다. 하지만, 소자에 발생되는 전압이 폐루프가 220.14[V], 개루프가 142.73[V]까지 상승함에 따라, 폐루프 철심구조시 전류제한소자의 부담이 가중됨을 알 수 있었다. 결과적으로 자속구속형 SFCL의 전력계통내 적용 시 각각의 철심구조에 따른 다양한 운전특성을 적절히 설계시 장점을 극대화 할 수 있을 것이다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2003년도 High Temperature Superconductivity Vol.XIII
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• pp.66-66
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• 2003

• 한국초전도ㆍ저온공학회논문지
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• 제11권3호
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• pp.35-39
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• 2009

The study for a protective relay system is one of the important technical issues on the power system application of Superconducting Fault Current Limiter (SFCL). We used Real Time Digital Simulator(RTDS) to study the true interaction of the protection system with the power system. RTDS modeling of SFCL is necessary to the detailed protective relay tests. In this paper, we developed an analysis model using RTDS for studying the transient behavior of 22.9kV SFCL and carried out closed-loop testing of protective relays in distribution power system with the developed SFCL model. The SFCL model has the operation mechanism of 22.9kV hybrid SFCL being developed by LSIS and KEPRI in Korea. The parameters of the model are based on the test data of the real SFCL. Power system planners and operators can solve the expected problems in power system application of SFCL using protective relay testing results.

• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.28-31
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• 2005

To verify the feasibility of bifilar winding type superconducting fault current limiter (SFCL) using BSCCO tape, two types of magnets were fabricated and tested by short-circuit in this research. Even if the FCL using high Tc superconducting (HTS) tape has zero resistance in normal state, it needs to be wound as a bifilar winding for zero inductance. Solenoid type and pancake type bifilar winding magnets are designed and fabricated with the same length of BSCCO tape. The test system consists of AC power supply, transformer, fault switch, load and bifilar winding magnet. The applied AC voltages during fault duration, 0.1s, were from 0.5V to 20V. The test results without bifilar winding magnet were compared with those with each type magnets. The test results include voltage against magnet, transport current and generated resistance curve. Thermal stability, the recovery time, was studied from the results of two type magnets. The pancake type was the most effective to limit fault current but the solenoid type was thermally the most stable. From this research, short-circuit characteristics of the two types were obtained.

• 한국초전도ㆍ저온공학회논문지
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• 제5권2호
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• pp.41-45
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• 2003

Resistance distribution in thin film type SFCL elements of different shunt layer thickness was investigated. The 300 nm thick film of 2 inch diameter was coated with a gold layer and patterned into 2 mm wide meander lines. The shunt layer thickness was varied by ion milling the shunt layer with Ar ions, and also by having the shunt layer grown in different thickness. The SFCL element was subjected to simulated AC fault current for measurements. It was immersed in liquid nitrogenduring the experiment. The resistance distribution was not affected by the shunt layer thickness at applied voltages that brought the temperature of the elements to similar values. This result could be explained with the concept of heat transfer from the film to the surroundings. The resistance distribution was independent of the shunt layer thickness because thick sapphire substrates of high thermal conductivity dominated the thermal conductance of the elements.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.43-45
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• 2008

In this paper, the operational characteristics of SFCL with magnetically coupled two coils were modeled and simulated by PSCAD/EMTDC. The dependence of the line voltage sag on the resistance of superconducting element during the fault period was analyzed. Through the analysis for the winding direction of two coils, the line voltage sag in case of the additive polarity winding was observed to be more improved compared to the case of the subtractive polarity winding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.83-85
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• 2004

We proposed the bridge type fault current limiter(FCL) using switching operation of high-Tc superconducting(HTSC) thin film. The proposed bridge type FCL consists of HTSC thin film, a diode bridge and a dc reactor. The controller for the operation of an interrupter is required in the conventional bridge type FCL to prevent the continuous increase of fault current after a fault happens. On the other hand, the proposed bridge type FCL can limit the fault current without the interrupter and the controller for its operation by the resistance generated when the gradually increased fault current exceeds HTSC thin film's critical current. We calculated the time when the gradually increased fault current started to be limited by the resistance generated in HTSC thin film after a fault happened and confirmed that it could be dependent on the amplitude of source voltage. The experimental results well agreed with the calculated ones from simulation.

• 한국초전도ㆍ저온공학회논문지
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• 제13권1호
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• pp.31-35
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• 2011

A Hybrid Fault Current Limiter(FCL) which has more advantages in fast response and thermal characteristics than a simple resistive FCL had been proposed by our group. The Hybrid FCL consists of a resistive FCL for the magnitude of the first peak of fault current, and a fast switch for detecting fault current and generating the repulsive force within a cycle in fault situation. In ideal case, the impedance of the fast switch wound with two other kinds of HTS tape is negligibly zero in normal operation. But, during the fault situation, each HTS tape has different quench characteristics because of asymmetric current distribution. And this phenomenon causes effective flux and this flux opens the switch through the repulsive force applied to a metal plate of the fast switch. The magnitude of the repulsive force affects the switching characteristics of the fast switch. It should be large enough to raise the metal plate up. Otherwise the arc re-out break which are caused by not enough repulsive force to raise the metal plate up can cause unintended operation of the fast switch. In this paper, the numerical calculation of the repulsive force applied to the metal plate of the fast switch in various combinations of HTS tapes was performed by using the short-circuit test and finite element method.