• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.46-48
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• 2008

The increase of fault current due to large demand has caused the capacity of power machines in power grid to increase. To protect the power system effectively from the large fault current, several superconducting fault current limiters have been proposed. however, in order to apply superconducting fault current limiters into power system, there are many problems such as cost, recovery, AC loss, and cryogenic. In order to solve these problems, hybrid superconducting fault current limiter(HSFCL) was proposed. In this paper, we modeled hybrid superconducting fault current limiter using PSCAD/EMTDC and analyed fault current limiting characteristic and total resistance of hybrid superconducting fault current limiter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1135-1140
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• 2008

Superconducting fault current limiters (SFCL) have been progressing due to the development of superconducting technology. The resistor type SFCL is one of the promising current limiting devices in power system for its effective operation. For proper application and operation of a SFCL, the prior investigation of fundamental characteristics and its effects to the distribution systems are needed. The most important current limiting behavior of a SFCL is dominated by quenching and recovery characteristics. In this paper, the resistive type SFCL was developed by using EMTP/ATPDraw and MODELS language. The operating characteristics and current limiting behaviors of the SFCL in distribution systems have been simulated and investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1299-1304
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• 2003

Fault current limiters (FCL) are extensively needed to suppress fault currents, especially for trunk power systems heavily connected to high voltage/large current transmission lines. Due to its ideal electrical behavior, high-temperature superconductor fault current limiter (HTSFCL) becomes one of the most important developing trends of limiters in power system. This paper describes the result of an investigation of the dielectric characteristics of turn-to-turn insulation for pancake and solenoid type reactor coil in liquid nitrogen. The influence of thickness in a variety length, on AC, DC and impulse surface flashover has been investigated. Also, the relationships between the number of turn and breakdown characteristics were clarified. The information gathered in this test series should be helpful in the design of liquid nitrogen filled DC reactor type HTSFCL.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1944-1947
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• 2012

In this work, we investigated quench characteristics of matrix-type superconducting fault current limiters (MFCLs) according to the turn number of reactors. The reactors used in MFCLs apply magnetic field to superconducting elements within reactors when fault currents surge into MFCL systems. It makes the fast and simultaneous quenches between superconducting elements. Also reactors decrease the fault power burden of superconducting elements by bypassing the partial fault currents to itself, when quench occurs. These structure proposed in this work can be expected to achieve much more current limiting capacity even though it uses less superconductors compared with other type SFCLs. Three reactors were made by Bakelite. These reactors with the turn number of 190, 380 and 570, had the length of 270 mm and diameter of 80 mm. We reported experimental results, including fault currents, fault voltages and resistance in superconducting elements according to the turn number of reactors. We confirmed that experimental results will be useful in next future plan for the real power grid.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.65-65
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• 2004

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.20-20
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• 2005

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.796-798
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• 2002

In these days, the interruption capability of some circuit breakers, which are installed in the transmission systems, is getting lower than the magnitude of the fault current because of continuous increase of power demand and relatively short power line which was installed in forms of mesh network As a result of these situations, fault current limiters (FCLs) are strongly necessary. There are various types which is investigated around the world, and new power apparatuses that have been newly considered and developed by many manufactures. In this paper, we considered resistive superconducting fault current limiters with YBCO thin films. The resistive limiters utilize a transition of YBCO films from superconducting to normal state caused by exceeding the critical current. By means of newly occurred impedance, the fault current will be limited effectively. Generally, a few current path patterns are available for YBCO films to enhance the current limiting performance of YBCO films. In this paper. the meander-type and the bi-spiral-type were used for current paths of YBCO flims. When YBCO films are quenched into the normal state, bubbles could be observed on the surface of YBCO films. Using our high-speed camera, the number of bubbles and the size of bubbles could be visualized and the relation between bubbles and current density was analyzed. By means of moving pictures of bubbles, we observed how the quench extended or how the heat was conducted in films.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2B
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• pp.123-130
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• 2012

MLP (Multi dimensional Limiting Process) is implemented to simulate shallow water flows, and its performance over conventional TVD limiters in multidimensional flows is verified through several numerical simulations. MLP was developed to control oscillations for multi-dimensional compressible flows and proved to improve accuracy, efficiency and robustness in compressible flows. In this study, we applies MLP to modeling shallow water equations(SWEs) given that the SWEs are amenable to be solved using the large range of numerical methods developed to deal with compressible flows and MLP has been yet used for SWEs. Simulation results through the benchmark tests show that MLP has favorable features such as numerical oscillation control and convergence behaviors comparable to the conventional limiters. Both numerical accuracy and stability are improved in multi-dimensional discontinuous flows.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.705-711
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• 2004

We propose novel OCDMA system with the structure of reconfigurable may encoder/decoder(RAE/ RAD), which are able to reallocate the 2-D optical codes to each subscriber and recover the transmitted data at all the receiving nodes. We have first implemented the double hard limiters composed of limiting amplifier(first hard limiter) that maintain a level of the encoded data from receiving node and AND detector(second hard limiter) for detecting the position of the encoded data and recovering the data. With the proposed system, it was successfully implemented to recover a specific channel data out of 16 code-multiplxed channels using FPGA and 4 DFB-LDs having distinct wavelengths. From experimental results, the code length resulted from increasing the number of the simultaneously connected channels has been reduced by using 2-D OCDMA multiplexed in time and wavelength instead of 1-D OCDMA. In addition, bit errors phenomenon on account of deterioration of autocorrelation peak-to-side lobe ratio is enhanced by using the double hard limiters composed of AND detector and limiting amplifiers.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.61-61
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• 2006