• 조명전기설비학회논문지
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• 제21권2호
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• pp.94-98
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• 2007

자속구속형 초전도 사고전류 제한기는 평상시 자기적인 결합에 의해 철심의 히스테리시스 손실이 발생하지 않는 특징이 있다. 그러나 사고시에는 사고전류증가로 인해 고온초전도 소자의 저항발생과 함께 철심의 포화가 발생할 경우 제한기의 사고전류제한 특성을 저하시키는 현상이 발생하게 된다. 따라서 본 논문에서는 이를 분석하고 억제하기 위한 설계방안을 도출하기 위해 자속구속형 고온초전도 사고전류 제한기의 구성요소인 자속구속 리액터의 히스테리시스 특성을 고려한 사고전류 제한특성을 분석하였다. 이를 위해 제한기의 등가회로와 사고전류 제한실험으로부터 히스테리시스 곡선을 도출하였다. 1, 2차권선의 인덕턴스 비에 따른 히스테리시스 곡선으로부터 인덕턴스비가 증가함에 따라 제한되는 사고전류크기는 증가한 반면 사고시 자속구속형 사고전류제한기의 구성요소인 철심의 포화가 억제됨을 확인할 수 있었다.

• 전기학회논문지P
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• 제59권4호
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• pp.477-480
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• 2010

Fault current in power system is expected to increase by demand of power capacity. Therefore, when the fault occurred, fault current was increased in the power system. Many studies have been progressed to limit the fault current. Superconducting fault current limiter (SFCL) is one of them which has been studied in worldwide. In this paper, we will analyze characteristics of a transformer-type SFCL by reclosing operation when the voltage increases. Twice opening times in the reclosing of circuit breaker were set as the 0.5 and 15 seconds, respectively. Turn's number of primary and secondary coils set 4:2 and we increased voltages from 120V to 280V for each experiment. By the current waveform, maximum fault current in second and third cycles was lowered when the voltage was increased. In the recovery waveform, recovery time was increased as the voltage was increased. The reason was that power burden of the SFCL increased when consumption power was increased, so the time to get back to SFCL took longer. We compared the characteristics of a resistive-type and transformer-type SFCL. As a result, we found that the fault current of a transformer-type was lower than resistive-type and recovery time of the SFCL was shorter. Consequently, transformer-type SFCL was more profitable for limitation of fault current and recovery time under the same condition for reclosing operation.

• 한국초전도ㆍ저온공학회논문지
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• 제14권3호
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• pp.13-17
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• 2012

KEPCO Research Institute has been researching a Superconducting Fault Current Limiter (SFCL) which is considered one of solutions of fault current problems with Korea Institute of Machinery & Materials (KIMM) and Hanyang University since 2011. In this paper, we fabricated a current limiting module and conducted electrical short circuit tests for checking the validity of the transmission level SFCL design. Based on the short circuit characteristics of the second generation High Temperature Superconductor (HTS), we analyzed the short circuit characteristics of 3 parallel connected superconducting wires. The structure of the HTS wire is as follows: the stainless steel stabilizer of $100{\mu}m$ is laminated on the superconductor layer and under the substrate, both of which are electrically jointed with solder. We fabricated the current limiting module which has 40 series and 6 parallel connections and studied the short circuit characteristics of the module under various voltage levels.

• 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.

• 전기학회논문지
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• 제68권4호
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• pp.593-597
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• 2019

We proposed a current Interruption type DC superconducting circuit breaker(I-DC SCB), a protection device that combines the current limiting technology of a superconductor with the cut-off technology of circuit breaker. Unlike existing protective devices, the current I-DC SCB is a device that combines two protection functions, notably improving failure probability and operational reliability. It is also applicable to all DC systems, such as HV, MV, and LVDC, due to the ease in capacity increase. The 100 kV I-DC SCB was designed after taking into account the actual power system conditions, followed by an analysis of the transient characteristics and the breaking range of the limiter. The results of the analysis showed that the I-DC SCB had a fault current limit of about 75% at the rated voltage, and completed the cut-off operation within about 20 ms.

• 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.

• Progress in Superconductivity
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• 제5권2호
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• pp.118-123
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• 2004

We investigated quench distribution in AU/YBCO thin film meander lines with a heater. Quench distribution during faults is important for superconducting fault current limter applications, because uniform quench allows application of higher voltages across the meander lines. AU/YBCO thin films grown on sapphire substrates were patterned into meander lines by photolithography. Gold films grown on the rear sides of the substrates were also patterned into meander lines, and used as heaters. Meander lines on the front and the rear sides were connected in parallel. The meander lines were subjected to simulated AC fault currents for quench measurements during faults. They were immersed in liquid nitrogen during the experiment for effective cooling. Resistance of the AU/YBCO meander lines initially increased more rapidly with the rear heater than without, and consequently the fault current was limited more. The resistance subsequently became similar, The resistance distribution was more uniform with the heater, especially during the initial quench. Quench was completed more uniformly and significantly earlier. This resulted in uniform distribution of dissipated power. These results could be explained with the concept of quench propagation, which was accelerated by heat transfer across the substrate from the rear heater.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.99-104
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• 2002

This study deals with the optimal design of a DC reactor type high-Tc superconducting fault current limiter(SFCL). The condition in which the cost function is minimized under given constraints is one of the things to be first considered in developing SFCLS. This condition is a group of the values corresponding to the variables the cost function depends on. In this paper, the length of tape was taken as a dependent variable, the inductance of DC reactor and the turns ratio of magnetic core reactors as independent variables. For the SFCL available at the level of 6.6kV-200A, we examined 4 cases; at the fault times of 80msec, 50msec, 30msec and 10msec. Since thyristors would be utilized instead of diodes, we chose the result at 10msec as the basic data. Considering safety factor 30%, our optimal design was decided to be the inductance 570mH, the critical current over 620A, the turns ratio 0.89 and the fault time within 20msec.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.216-219
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• 2002

This paper describes the modelling method of the Superconducting Fault Current Limiters (SFCL) for Real-Time Digital Simulator (RTDS). The simulations in this paper were carried out using the R type SFCL. The R type SFCL is developed by using User Defined Component (UDC).

• 대한전기학회논문지:전력기술부문A
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• 제54권5호
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• pp.226-233
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• 2005

As the power demand has been increasing, a fault current problem is becoming more serious in real power system. Various ways like bus-split operation, transmission line open operation, are used in Korean power system for solving the problem. In this time, superconducting FCL(Fault Current Limiter) has been developed as a vary attractive alternative since HTS(High Temperature Superconductivity) was discovered. Korea, a project developing superconducting FCL to apply to 154kV transmission system is proceeding. Therefore, a power system analysis for SFCL application to power system is necessary, This paper presents the determination of quenching resistance and the selection of optimal cites when 154kV HTS-FCL is applied to Korean power system.