• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.110-113
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• 2002

The high-tc superconducting fault current limiters (SFCL) are studied worldwide to be classified as resistive type or inductive type such as magnetic shielding type and dc reactor type. This Paper deals with an open core type SFCL, a kind of magnetic shielding type SFCL. We manufactured a 30 kVA open core type SFCL. It was modified from the old one with a rated power of 8 kVA. We stacked four superconducting tubes as magnetic shielding material and used the same primary winding as the old one. The experiments were performed with a maximum source voltage of 1 kV. The results show that the fault current in the source voltage of 1 kVrms was reduced to be about 105 Apeak, which was calculated to be about 22 % of the fault current in the system without an SFCL.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.40-44
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• 2001

Recently. the high-tc superconducting fault col-rent limiters (SFCL) are studied worldwide to be classified as a resistive type or an inductive type such as a magnetic shielding type and a inductive type. The high-tc SFCL wish an open core belongs to the magnetic shielding type SFCL. Unlike conventional magnetic shielding type SFCLS it uses the open core to reduce the mechanical vibrations and installation space, The high-tc SFCL with an open core was designed and manufactured by stacking three BSCCO 2212 tubes. It was tested in the maximum source voltage of 400 Vrms. The results such as the reduction of fault current and impedance of the SFCL are described in this paper. The results show that the fault current in the source voltage of 400 Vrms was reduced to be about 123 Apeak. about 3.9 times greater than the normal state current. Also, the impedance of the high-tc SFCL was about 9${\Omega}$ about 9 times greater than the normal state impedance. The impedance of the SFCL appears just after the fault, and its size is dependent on the source voltage. From the impedance, the inductance of the SFCL was calculated.

• 한국초전도ㆍ저온공학회논문지
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• 제15권4호
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• pp.26-29
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• 2013

Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

• 조명전기설비학회논문지
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• 제16권3호
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• pp.74-83
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• 2002

본 논문은 전력설비에 조기적용이 예상되는 초전도한류기의 파라메타를 정의하고 앞으로 개발방향을 제시하기 위하여 한류기의 동작원리, 특성 및 계통조기적용가능성들을 근거로 파라메타의 특성을 비교 ·평가하였다. 또한 한류기의 계통적용효과를 분석하기 위하여 SFCL이 기간 특고압 모델계통에 도입한 경우를 상정하여 3선지락 고장에서 저항형과 유도형 SFCL의 도입 효과에 대하여 RTDS (Real Time Digital Simulation)/EMTDC(Electromagnetic Transient DC)로 시뮬레이션하였다. 특히 저항형과 유도형의 한류효과의 비교 평가, 모선전압의 저하 억제 및 계통과 한류기의 파라메타와의 관련성에 대하여 검토하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제5권2호
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• pp.36-40
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• 2003

Inductive superconducting fault current limiter(SFCL) with DC reator rated on 6.6k $V_{rms}$/200 $A_{rms}$ has been developed in Yonsei University. The development of the DC reactor is the key technology in this type SFCL. This paper deals with the fabrication and characteristic test of the DC reactor. For the development of this magnet, the winding machine for high-Tc superconducting solenoid was manufactured. Using this machine, a large-scale HTS solenoid using Bi-2223 tape was fabricated successfully. This coil has 5 layers which are connected in series each other. The inductance of the DC reactor coil is 84mB. The cooling system was the sub-cooled nitrogen whose temperature is about 65K. The characteristic test of the coil was performed. The full quench current of this coil is about 490A.90A.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.234-236
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• 2003

The cryogenic system for inductive superconducting fault current limiter (SFCL) has been investigated recently. In this investigation, the sub-cooled nitrogen cryogenic system was adopted to enhance the performance of DC reactor for 6.6㎸/200A inductive SFCL. In sub-cooled nitrogen state at 64K, the critical current value and the thermal conductivity are larger than those of saturated nitrogen state at 77K and the electrical insulation capacitance should be remarkably enhanced. The solenoid type of 84mH superconducting DC reactor was fabricated and cooled down to 64K by using sub-cooled cooling method with GM-cryocooler and rotary pump. The fabrication techniques of cryogenic system and some experimental results such as cooling down characteristic are introduced in this study. Moreover, the sub-cooled nitrogen cryogenic system was detailedly introduced in this paper.

• 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.

• 한국초전도ㆍ저온공학회논문지
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• 제5권3호
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• pp.57-61
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• 2003

In this investigation, the 6.6kV/200A Inductive Superconducting Fault Current Limiter (SFCL) was designed and fabricated. The type of DC reactor for Inductive SFCL was determined as solenoid type during the period of $1${st}$ year research. The 5 bobbins for DC reactor were fabricated and each bobbin was wound with 4 stacked High-Tc superconducting (HTS) tapes and the 5 bobbins were connected in series. The critical current and inductance of DC reactor were simulated by Finite Element method (FEM) and compared with the measured results. The characteristics of DC reactor were enhanced in sub-cooled nitrogen system rather than in liquid nitrogen system. The procedures to accomplish the sub-cooled nitrogen system and the experimental results were introduced in detail. Moreover, the design of sub-cooled nitrogen cryogenic system for next year research was introduced in brief.

• 한국초전도ㆍ저온공학회논문지
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• 제8권2호
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• pp.29-32
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• 2006

An advanced superconducting fault current limiter (SFCL) using $high-T_c$ superconducting (HTS) wire has been developed. The SFCL has a non-inductively wound magnet for reducing loss in normal state. Two types of non-inductively wound magnets, the solenoid type and the pancake type, were designed and manufactured by using Bi-2223 wire in this research. Short-circuit tests of the magnets were performed in sub-cooled $LN_2$ cooling system of 65 K. The magnets are thermally more stable and have a higher critical current in 65 K sub-cooled $LN_2$ cooling system than in 77 K saturated one. Because the resistivity of matrix at 65 K is lower than the resistivity at 77 K, the magnets generate a small resistance to reduce the fault current when the quench occurs. The magnets could limit the fault current to low current level with such a small resistance. The current limiting characteristic of the magnets was analyzed from the test result. The solenoid type was wound in parallel to make it non-inductive. The pancake type was also connected in parallel to be compared with the solenoid type in the same condition. The solenoid type was found to have a good thermal stability compared with the pancake type. It also had as large resistance as the pancake type to limit the fault current in sub-cooled $LN_2$ cooling system.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.338-342
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• 1999

전력계통에 저항형과 유도형 초전도 한류기를 적용하였을 때 사고각별 전류제한 효과를 살펴보았다. S1 변전소로부터 S2 변전소까지 거리의 약 60%지점에서 사고가 발생하였을 때, 1선 지락사고에서 S1측 고장전류는 사고각 0 $^{\circ}$ 의 경우 약 39kA이었으며 이는 정상전류의 약 87배이었고, 5주기 이후의 전류값도 53배에 달하는 약 23 kA값을 보여주었다. 차단기 전단에 저항형과 유도형 초전도 한류기를 적용하였을 때 사고각별 전류제한효과를 보면, 사고각 0 $^{\circ}$ 인 경우 저항형은 사고발생 직후 최대 한류전류값이 최고 39 kA, 최종 한류전류값이 약 15 kA이었다. 이때 과도상태에서 직류분은 거의 발생하지 않았다. 유도형은 사고발생 직후 최고 39 kA와 최종 12 kA의 전류값을 나타내었다. 이때 직류분은 약 3 kA이었다. 2선 지락사고에서 고장전류는 사고각 0 $^{\circ}$ 의 경우 최고 약 56 kA이었으며 이는 정상전류의 약124배이었고, 5주기 이후의 전류값도 76배에 달하는 약 34 kA값을 보여주었다. 선로에 저항형과 유도형 초전도 한류기를 적용한 경우 사고각별전류제한 효과를 보면, 사고각이 0 $^{\circ}$ 일때 저항형은 사고발생 직후 최대 한류전류값이 최고 44kA, 최종한류전류값이 약 15 kA이었다. 이때 과도상태에서 직류분은 거의 발생하지 않았다. 유도형은 사고발생 직후 최고 44 kA와 최종 14 kA의 전류값을 보여주었다. 이때 직류분은 약 4 kA이었다. 1, 2선 지락사고를 종합해 보면 2선 지락사고가 사고전류의 크기와 유도형의 직류분 감쇄폭이 약간 컸을 뿐 전력계통에서 초전도 한류기의 적용은 같은 조건(초전도 한류기의 최종 임피던스100${\omega}$)하에서 전류제한 능력면에서는 유도형이 유리하고 초기 과도상태에서 직류성분의 발생측면은 저항형이 장점을 가지고 있음을 알 수 있었다. 아울러 앞으로는 quench 시간에 따른 전류제한 현상에 관한 simulation을 수행 하고자 한다.