• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.252-254
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• 2006

The recent improvement in the performance of digital processor, the application of control technology, which used in the HVDC(High Voltage Direct Current) system with the digital processors, has increased. Having this research development as the basis, this paper presents an achievement of progression by tuning the parameter of PI controller based on Genetic Algorithms(GAs) and by controlling with PI controller with a developed simulator by applying the Matrix operating function, voltage source switching element, modified nodal analysis which can include transformer and the backward Euler which does not create the problem of numerical oscillation. As a result, I expect this development in the simulator HVDC System to bring more application in the field of control technology research with an expanded practicality.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1651-1653
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• 1996

As electrode materials like as Cu-Pb, Cu-Bi, WC-Ag, W-Ag for vacuum circuit breaker have high chopping current or bad insulation-recovery characteristics, it can affect induction machinery like as transformer and motor. To produce low surge electrode material, it have been suggested Co-Ag-Se electrode which were infiltrated with Ag-Se intermetallic compound into sintered Co matrix. In this study, we would like to represent that production method and microstructure of Co-Ag-Se electrode material. The microstructure and characteristics of Ag-Se intermetallic compound and Co-(Ag-Se) electrode were investigated by using SEM, XRD, EPMA.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.422-425
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• 1997

This paper describes a resonant fly-back converter for high-voltage de distribution system. The proposed converter operates to change high-voltage de into low-voltage de with isolation and large converting ratio. The converter has a thyristor switch with an LC resonant circuit for commutation in the primary side of the gap transformer. The operation of the proposed system was verified through computer simulations and hardware scaled-model tests. The proposed system can be implemented with commercially available components and proven technologies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.35-41
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• 2009

This paper proposes a stand alone type single-phase fuel cells micro-source with a voltage sag compensator for compensating the ac output voltage variations (sag or swell) of micro-source. The proposed micro-source is consist of a PEM(polymer electrolyte membrane) fuel cells simulator, a full bridge de converter, a 60Hz PWM(pulse width modulation) VSI(voltage source inverter), and a voltage sag compensator. Voltage sag compensator is similar to the configuration of hybrid series active power filter, and it is directly connected to micro-source through the injection transformer. Compensation algorithm of a voltage sag compensator adopts a single phase p-q theory. Effectiveness of the proposed the system is verified by the PSIM(power electronics simulation tool) simulation in the steady state and transient state which the proposed system is able to simultaneously compensate the harmonic current and source voltage sag or swell.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.442-443
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• 2008

This paper describes modeling using the EMTP/ATPDraw for reclosing analysis in 154kV combined transmission systems, and analyzes switching overvoltage. Current transformer established at lead-in area and lead-out area in transmission line and circuit breaker were modeled using TACS in the EMTP/ATPDraw. And also MODELS was constructed by signal processing of the operating reclosing. The simulation was carried out the switching overvoltage according to the length of overhead and underground transmission line, overvoltage between sheath and earth, and voltage between joint boxes.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.681-682
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• 2008

최근 다양한 부하들로 인해, 배전용변압기로 사용되고 있는 몰드변압기의 운전조건이 가혹해 지고 있다. 특히, 전력변환장치와 연계된 몰드변압기의 경우, 부하의 운전특성에 따라 편자(偏磁)현상이 발생하며 이로 인해 직류성분의 전류가 몰드변압기로 유입된다. 이는 철심의 포화현상 및 변압기의 손실 증가를 유발하여 국부과열 문제로 인한 사고로 이어질 우려가 있다. 본 연구에서는 이러한 문제를 해결하기 위해, EMTP 과도해석 프로그램을 활용하여 직류성분 전류에 의해 증가되는 몰드변압기의 여자전류를 계산하고, 이를 토대로 철심의 자속밀도 변화를 계산하였다. 직류성분 전류의 크기에 따라 철심의 적정 운전자속밀도를 고려하여 몰드변압기를 설계함으로써 직류전류 유입시에도 안정적인 운전이 가능할 것으로 사료된다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2301-2302
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• 2008

We experimentally investigated discharge phenomena inside vacuum interrupter at 1 to 20 Torr to simulate the vacuum leakage. We used glass type of vacuum interrupter where the internal pressure and the type of gasses can be varied according to requirement. The experiment is conducted under ac applied voltage and the experimental circuit is constructed to simulate the actual circuit used in cubical type insulated switchgear. We used two types of gases such as air and SF6. The use of glass type vacuum interrupter allowed us to measure discharges occurring in vacuum interrupter optically. We measured and discussed the discharge occurring in both gases with a current transformer and ICCD camera. We also revealed that electromagnetic wave spectra emitted by the discharge have same frequency range for both gasses.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.71-73
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• 2008

본 논문에서는 유한요소법을 이용한 전력용변압기의 와전류 손실 해석에 대해 다루고자 한다. 와전류 손실 해석에서 사용할 전력용 변압기 설계 치수는 3D 자계 해석을 통해 검토하였다. 검토한 치수를 바탕으로 전력용 변압기를 2D 모델링하여 와전류 손실 해석을 하였으며, 2D, 3D 두 해석 결과 비교를 통해 와전류 손실에 대해 분석 및 검토하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.365-366
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• 2015

This paper describes the analysis on thermo-mechanical characteristics of underground cable termination. Specially, the interface pressures between stress relief cone and XLPE insulation were analysed according to the change of conductor temperature and ambient temperature. This interface pressures were measured by real test with current transformer and chamber and the interface pressure was changed with conductor and ambient temperature. This paper will continue to perform the test with various cases, then the relation between low interface pressure and breakdown will prove with test results in the near future.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.768-769
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• 2015

본 논문에서는 3상, 1250MVA, 345kV급 전력용 변압기의 하우징 영역에 대한 온도상승 연구를 유한요소법과 시험을 통하여 수행하였다. 하우징 영역에 대한 전자계 요한요소 해석을 통해 와전류 손실을 수행하였고, 이를 열원으로 하여 변압기 내 외부 냉각조건을 고려하여 온도상승 분포와 최고온도 상승 값을 해석하였다. 이를 제작된 변압기를 대상으로 온도센서 및 열화상 카메라를 이용한 측정 데이터와 비교하여 검증하였다.