• Title/Summary/Keyword: limiter

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Influence of polymer coating on SFCL recovery under load

  • Gorbunova, D.A.;Kumarov, D.R.;Scherbakov, V.I.;Sim, Kideok;Hwang, Soon
    • Progress in Superconductivity and Cryogenics
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    • v.21 no.4
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    • pp.44-47
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    • 2019
  • This paper is a study of recovery under load process of superconducting fault current limiter (SFCL). SFCL consists of five parallel-connected high-temperature superconductor (HTS) tapes additionally stabilized by stainless tape. Previously, HTS was heated by current pulse to simulate a short circuit in a power grid. During the cooling period, the current amplitude decreased to 23% or less of HTS critical current value, which is the simulation of network re-switching. When HTS with a polymer coating is cooled, temperature gradient on thermal insulation layer occurs, that prevents a boiling crisis and improves the heat sink into liquid nitrogen. Two samples are coated with a 30 ㎛ and 50 ㎛ polylactide (PLA) layers, reference sample has no polymer coating on it. Samples with a polymer coating show 3-5 times faster cooling than the reference one.

Investigation of the Feasibility of a Bus-bar coupled SFCL in the 154 kV KEPCO Grid (154 kV 초전도 한류기 모선연계 적용 연구)

  • 윤용범;현옥배;황시돌;김혜림
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.291-293
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    • 2003
  • Applicability and economical feasibility of a Superconducting Fault Current Limiter (SFCL) have been investigated using the PSS/E simulation for a bus bar coupling at the real 154 ㎸ KEPCO power grid near Seoul. For the investigated substation, the maximum fault current exceeds the interruption rating of 4 circuit breakers (CB) out of 9 installed in the substation. The simulation showed that a SFCL installed in the bus tie position effectively limits the fault currents to save 4 CBs, which are to be replaced by ones of gloater interruption rating, otherwise. We suggest that the optimum resistance of the SFCL be 10 Ohm for the given grid.

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Fault Current Limiting Characteristics of Resistive Type SFCL using Transformer (변압기를 이용한 저항형 고온초전도 전류제한기의 한류 특성)

  • 임성훈;최효상;고석철;이종화;강형곤;한병성
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.288-290
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    • 2003
  • The transformer is expected to be an essential component of resistive type superconducting fault current limiter (SFCL) for both the increase of voltage ratings in SFCL and the simultaneous quench due to different critical current between HTSC elements. However, for the design to prevent the saturation of iron core and the effective fault current limitation, the analysis for operation of SFCL with consideration for the magnetization characteristics are required. In this paper, the fault current limiting characteristics related with the magnetization ones were investigated through the variation of the ratio of the number of turns in the 1st and the 2nd windings. The proper design condition with variation of the number of turns to make the effective fault current limiting operation could be determined.

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A Flowfield Analysis Around an Airfoil by Using the Euler Equations (Euler 방정식을 사용한 익형 주위에서의 유동장 해석)

  • Kim M. S.
    • 한국전산유체공학회:학술대회논문집
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    • 1999.05a
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    • pp.186-191
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    • 1999
  • An Euler solver is developed to predict accurate aerodynamic data such as lift coefficient, drag coefficient, and moment coefficient. The conservation law form of the compressible Euler equations are used in the generalized curvilinear coordinates system. The Euler solver uses a finite volume method and the second order Roe's flux difference splitting scheme with min-mod flux limiter to calculate the fluxes accurately. An implicit scheme which includes the boundary conditions is implemented to accelerate the convergence rate. The multi-block grid is integrated into the flow solver for complex geometry. The flowfields are analyzed around NACA 0012 airfoil in the cases of $M_{\infty}=0.75,\;\alpha=2.0\;and\;M_{\infty}=0.80,\;\alpha=1.25$. The numerical results are compared with other numerical results from the literature. The final goal of this research is to prepare a robust and an efficient Navier-Stokes solver eventually.

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OPTIMIZATION OF A DRIVER-SIDE AIRBAG USING KRIGING AND TABU SEARCH METHODS (크리깅과 타부탐색법을 이용한 운전석 에어백의 최적설계)

  • Kim, Jeung-Hwan;Lee, Kwom-Hee;Joo, Won-Sik
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1035-1040
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    • 2004
  • In the proto design stage of a new car, the performance of an occupant protection system is often evaluated by CAE instead of the real test. CAE predicts and recommends the appropriate design values hence reducing the number of the real tests. However, the existing researches using CAE in predicting the performances do not consider the uncertainties of parameters, in which inconsistency between the actual test results and CAE exists. In this research, the optimization procedure of a protection system such as airbag and load limiter is suggested for the frontal collision. The DACE modeling known as Kriging interpolation is introduced to obtain the meta model of the system followed by the tabu search method to determine a global optimum. Finally, the distribution of a suggested design is determined through the Monte-Carlo Simulation.

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Quench propagationin resistive SFCL (저항형 초전도 한류기에서의 퀀치 전파)

  • 김혜림;현옥배;최효상;황시돌;김상준
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.85-88
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    • 1999
  • We fabricated resistive superconducting fault current lmiters based on YBa$_2$Cu$_3$O$_{7}$ thin films and investigated their quench propagation characteristics. The YBa$_2$Cu$_3$O$_{7}$ film was coated with a gold layer and patterned into 1 mm wide meander lines by photolithography. The limiters were tested with simulated fault currents of various fault angles and amplitudes. The quench propagation characteristics were explained based on the heat transfer within the film as well as between the film and the surrounding liquid nitrogen. The quench completion time strongly depended on the potential fault current. It was 1 msec at the peak fault current of 76 A/peak/ and corresponding quench propagation speed was 43 m/sec (film cross section: 4 x 10$^{-6}$ $\textrm{cm}^2$).

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Fabrication and Characterization of BSCCO System High-Temperature Superconductor Using Centrifugal Forming Process (원심성형법을 이용한 BSCCO계 고온초전도체 제조 및 특성 분석)

  • 박용민;장건익
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.189-192
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    • 2000
  • High-temperature superconductor of Bi-2212 system was fabricated by CFP(centrifugal forming process). To make a uniform specimen slurry was prepared in the ratio of 7:3(powder:binder) and ball milled for 24 hours. Milled slurry was charged into a rotating mold with 450 rpm and dried at room temperature. Then the specimen was performed binder burn-out at 35$0^{\circ}C$ and heated for partial melting to 86$0^{\circ}C$. XRD analysis of most specimens were shown 2212 phase and observed a local plate shaped microstructure with a well aligned c-axis direction from SEM images. T$_{c}$(Critical temperature) of Bi-2212 was 64K.K.

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A Study on SFCL Systems for Future Korean T&D Power System Application Considering Auto Reclosing Actions of Protection System (미래 송배전계통에서의 자동재폐로 동작을 고려한 초전도한류시스템에 관한 연구)

  • Lee Seung Ryul;Kim Jong-Yul;Yoon Jae Young
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.12
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    • pp.580-585
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    • 2005
  • The recovery time of developing SFCL(Superconducting Fault Current Limiter) has an uncertainty. In general, the recovery time is estimated at 1 sec and more, even though the progress of SFCL technology is considered. However, auto reclosing time of circuit breaker is 0.3 or 0.5 sec in Korean power system. It is impossible to apply only one SFCL to power system because the recovery time is over the reclosing time of protection system. This study proposes two new SFCL systems for power system application. The proposed systems consider auto reclosing action for the protection in practical power system and consist of tow parallel SFCLs.

The Study on Reducing Voltage Sags Due to Single Line Short Circuit Faults in Distribution System (배전계통 단선지락사고에 의한 전압저하 저감방법에 관한 연구)

  • 오용택;김진성
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2003.11a
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    • pp.111-116
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    • 2003
  • Recently, power-electronics equipments or machine that microprocessor is included and computers have been installed continuously in industrial process or region of electronics customer. So concern for power quality, especially sags has been increased. Because those equipments are very sensitive to sags. The sag is phenomenon that magnitude of load voltage temporarily decreases because of power system fault. If a certain equipment in industrial process have any trouble result from sag, it can cause utility to be charged for enormous economics loss. Therefore it need to analyze the characteristic of sag and then mitigation method for sags in distribution system in oder to increase reliability. This paper gives an overview of sags characteristic due to short circuit fault in distribution system and after a general discussion of the various forms mitigation, gives a sags mitigation method with concentrating on mitigation-device interface method, especially FCL that is Fault Current Limiter.

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Implementation of OCDMA System with Double Hard Limiters (이중 하드리미터 구조의 OCDMA 시스템 구현)

  • 권순영;김범주;박종대
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.807-809
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    • 2004
  • 본 논문에서는 광 부호분할다중접속(OCDMA) 시스템 구현을 위해 각 가입자의 시간ㆍ파장영역의 2차원 부호할당 및 변경이 가능하고 다중 사용자의 암호화된 데이터의 동시 전송과 모든 수신 노드에서 복원이 가능한 OCDMA 시스템 구조를 제안하였다. 또한 기존의 이중 광 하드리미터를 제한증폭기와 AND 게이트를 사용하여 이중 전기 하드리미터를 구현하였다. 서로 다른 파장을 갖는 레이저 다이오드와 FPGA를 이용한 전기 상관기로서 시간과 파장영역의 2차원으로 부호 다중화된 동시 가입자 신호에서 특정 가입자의 신호를 복원하였고, 제한 검출기와 위치 검출기의 이중 전기 하드리미터를 이용하여 MAI로 인한 기존 OCDMA 시스템에서의 식별력 저하와 비트오류 문제를 해결하였다.

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