• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.916-917
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• 2001

We investigated the properties of a hybrid type superconducting fault current limiter (SFCL), which consists of a transformer with multiple secondary windings and resistive $YBa_2Cu_3O_7$ (YBCO) thin film stripes. The secondary windings of the transformer were coupled with each other, and a superconducting current limiting unit of YBCO stripes was connected to each of them as a switch. Simple connection in series of SFCL units tends to produce imbalance in power among the units due to slight differences in quench current. In current design, magnetic coupling between the SFCL units provides a solution to power dissipation imbalance, inducing simultaneous quench by current redistribution in the YBCO films.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.57-63
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• 2015

Fault currents characteristics contain decaying DC offset. First cycle peak value of fault currents is higher than steady-state fault current value. These characteristics can affect the operation of protective device. To reduce the asymmetric fault current, the method using a series connection of two hybrid-type Superconducting Fault Current Limiter(SFCL) components, an auxiliary SFCL and a main SFCL, has been proposed. The auxiliary SFCL limits the first half cycle fault current, while main SFCL limits the steady state fault currents. This paper proposed a decision method of the optimal insertion resistance of auxiliary and main SFCL components. To verify the effectiveness of proposed scheme, the various simulations are performed by using Electromagnetic Transient Program(EMTP).

• 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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• 2009.07a
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• pp.294_295
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• 2009

Superconducting fault current limiter (SFCL) is an power device of a novel concept. While SFCLs generate no ohmic loss during the operation carrying normal currents, they can limit fault currents very fast making large impedance by their quench characteristics. In 2006, KEPCO has developed a distribution class hybrid type SFCL by a collaborative research project with LS industrial systems. The SFCL has merits in practical and economical points of view. In the SFCL, the superconductor just plays a role of a fault detector and the current limiting is completed by the other current limiting element made of normal metals throu호 the line commutation. As a result, the required amounts of superconductors can be reduced considerably. Consequently, the hybrid SFCL can be fabricated with small size and cost, maintaining perfect current limiting performance. Currently, KEPCO is carrying out a research project at Gochang power test center for the purpose of the verification test of the 22.9 kV/ 630 A class SFCL for the practical application in real grid. Through the project, a long term operational test and fault current test will be done. In this paper, the back ground of development and installation of the SFCL will be explained and the operation plan of the SFCL for the verification test is also introduced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.56-62
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• 2014

When fault currents contain decaying DC offset, the peak value of the fault current in the first cycle of the fault period is higher than the fault current during the steady-state period. To reduce the asymmetric fault current, this paper proposes an operation scheme using the series connection of two hybrid type Superconducting Fault Current Limiters (SFCLs) : an auxiliary SFCL and a main SFCL. The proposed method calculates the fault angle by comparing the zero-crossing time with fault detection time. According to the fault angle calculated, an auxiliary SFCL operates to reduce an asymmetric fault current during half a cycle after fault occurrence. After this process, the fault current is limited by a main SFCL. To confirm the usefulness of the proposed method, case studies using Electro-Magnetic Transients Program (EMTP)/Alternative Transient Program (ATP) Draw are perfomed.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.172-174
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• 2008

A fault current limitation using fault current limiter(FCL) is very important for power system operation. In recent year, a number of research have been performed and still Progressing about the super conducting fault current limiter(SFCL), To protect the power system effectively from the large fault current, several superconducting fault current limiters proposed. However, there are many problem such as cost, recovery and ac loss. To solve these problems, hybrid superconducting fault current limiter(HSFCL) have been proposed. In this paper, HSFCL are modeled using (Electro Magnetic Transient Program - Restructured Version) EMTP-RV.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.223-225
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• 2008

In order to apply SFCLs into electric power systems, the urgent issues to be settled are as follows, such as initial installation price, operation and maintenance cost due to ac loss of superconductor and the life of cryostat, and high voltage and high current problems. We designed novel hybrid SFCLs which combine superconductor and conventional electric equipments including a vacuum interrupter, an electro-magnetic contactor and a current limiting reactor. The main purpose of the hybrid SFCL is to drastically reduce total usage of superconductor by adopting current commutation method by use of the superconductor and the fast switch. According to protective coordination and performance, we investigated two concepts of Hybrid SFCLs. First is a half cycle fault current limitation type and second is a non-half cycle fault current limitation type. We concluded that the non-half cycle fault current limitation type is batter than the other.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.27-27
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.246-247
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• 2007

최근 KEPRI-LSIS가 공동 개발한 하이브리드형 초전도 한류기 동작 시, 사고 검출을 담당하는 초전도체의 최적 설계에 적용하기 위하여 Au/YBCO 박막의 ��치 회복 특성을 조사하였다. $600\;V_{rms}$, 3 ms의 사고가 초전도 박막에 인가되었을 때, ��치가 종료된 이후 초전도성을 회복하기 위해 142 ms의 시간이 소요되었다. 또한 인가 시간이 증가함에 따라 소요 시간도 비례하여 증가하여 4 ms 동안 인가되었을 때, ��치 회복 시간은 272 ms로 측정되었다.