• Proceedings of the KIEE Conference
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• 2002.07a
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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).

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.404-411
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• 2010

The present paper deals with the continuous work of extending multi-dimensional limiting process (MLP), which has been quite successfully proposed on two- and three-dimensional structured grids, onto the unstructured grids. The basic idea of the present limiting strategy is to control the distribution of both cell-centered and cell-vertex physical properties to mimic a multi-dimensional nature of flow physics, which can be formulated as so called the MLP condition. The MLP condition can guarantee a high-order spatial accuracy without yielding spurious oscillations. Recently, MLP slope limiter was proposed based on the MUSCL-type reconstruction in two-dimensional case and it can be readily extended to three-dimensional case. Through various numerical analyses and extensive computations, it is observed that the proposed limiters are quite effective in controlling numerical oscillations and very accurate in capturing both discontinuous and continuous multi-dimensional flow features on 3-D tetrahedral grids.

• Journal of IKEEE
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• v.11 no.3
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• pp.122-128
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• 2007

Sinusoidal voltage-controlled oscillators (VCOs) based on Colpitts and Hartley oscillators are presented. They consist of a LC parallel-tuned circuit connected in a negative-feedback loop with an OTA-R amplifier and two diode limiters, where the inductor is simulated one realized with temperature-stable linear operational transconductance amplifiers (OTAs) and a grounded capacitor. Prototype VCOs are built with discrete components. The Colpitts VCO exhibits less than 1% nonlinearity in its current-to-frequency transfer characteristic from 4.2 to 21.7 MHz and ${\pm}$95 ppm/$^{\circ}C$ temperature drift of frequency over 0 to $70^{\circ}C$. The total harmonic distortion (THD) is as low as 2.92% with a peak-to-peak amplitude of 0.7 V for a frequency-tuning range of 10.8-32 MHz. The Hartley VCO has the temperature drift and THD of two times higher than those of the Colpitts VCO.

• Journal of Magnetics
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• v.20 no.4
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• pp.400-404
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• 2015

Various kinds of winding arrangements can be used to enable fault current limiters (FCL) to tolerate higher forces without resulting in a substantial increase in construction and fabrication costs. In this paper, a distributed winding arrangement is investigated in terms of its effects on the short-circuit forces in a three-phase FCL. The force magnitudes of the AC supplied windings are calculated by employing a finite element-based model in the time stepping procedure. The leakage flux and radial and axial force magnitudes obtained from the simulation are compared to those obtained from a conventional winding arrangement. The comparison shows that the distributed winding arrangement significantly reduces the radial and, especially, the axial force magnitudes.

• Progress in Superconductivity
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• v.5 no.2
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• pp.136-140
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• 2004

We fabricated and tested a resistive superconducting fault current limiters (SFCL) operated at 3.8 ㎸ based on YBCO thin films. The SFCL was composed of 7 components connected in series. Each component was designed to be capable of current limiting at 600 V, and has a SiC shunt resistor ( $R_{s}$) of 40 Ω in Parallel. Short circuit tests were carried out fur 0 and 90 degree faults lasting fur 5 cycles. The test results showed that the 7 components were quenched simultaneously under the safe quenches and evenly shared the applied voltage. The SFCL successfully suppressed the fault currents below 94 $A_{peak}$ within the quarter cycle after fault.t.t.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.89-93
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• 2002

We investigated the resistance distribution n 4"diameter SFCLS. $YBa_2CU_3O_7$ films coated in-situ with a gold layer were patterned into 3 mm wide 142 cm long meander lines by Photolithography. The limiters were tested with simulated fault currents. The resistance was uniform all over the film except at the edge. At lower source voltages, CFCLs did not quench simultaneously and the resistance distribution was less uniform. Compared with 2" diameter SFCLS 4" SFCLS had similar values and time dependence of resistivity at similar electric fields The resistance distribution was more uniform in 4" SFCLS. The area at the edge where the distribution was not uniform was around 3 mm wide in SFCLs of both sizes. The experimental results were quantitatively explained with a heat transfer concept.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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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.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.91-94
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• 2000

We fabricated resistive super- conducting fault current limiters (SFCL) based on YBCO thin films grown on 2" diameter $Al_{2}O_{3}$ substrates. Two SFCLs with nearly identical properties. two SFCLs with nearly identical properties were connected in series to investigate simultaneous quenching. There was a difference of several half cycles in their quench starting time, although the difference was not more than 0.1 msec when they were operated separately. This imbalance was removed by connecting a shunt resistor to an SFCL in parallel. Increased power input at high voltages also reduced the initial imbalance in power dissipation. Further efforts on the simultaneous quench in SFCLs connected in series are on the way through methods such as the artificial control of quench speed.peed.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.133-135
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• 2000

We fabricated resistive super- conducting fault current limiters (SFCL) based on YBCO thin films grown on a 2" diameter $Al_{2}$O_{3} substrate. The minimum quench current of the current minimum quench current of the current limiting element was about 8 $A_{peak}. This SFCL successfully controlled the fault current below 14.3 $A_{peak} at the voltage of 100$V_{rms}, which is otherwise to increase up to 141$A_{peak}. and the quench completion time is less than 3 msec. The temperature of the current limiting element rose to about 200K in 3 cycles after fault. The SFCL showed reproducible characteristics during hundreds times of repeated experiments.ents.

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.21-25
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• 2013

In power grid, in order to level out the generation with demand, up-gradation of the system is occasionally required. This will lead to more fault current levels. However, upgrading all the protection instruments of the system is both costly and extravagant. This issue could be dominated by using Smart Fault Current Controller (SFCC). While the impact of Fault current Limiters (FCL) in various locations has been studied in different situations for years, the performance of SFCC has not been investigated extensively. In this research, SFCC which has adopted the characteristics of a full bridge thyristor rectifier with a superconducting coil is applied to three main locations such as load feeder, Bus-tie position and main feeder location and its behavior is investigated through simulation in presence and absence of small Distributed Generation unit (DG). The results show a huge difference in limiting the fault current when using SFCC.