• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1200-1202
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• 1998

전력 사업자들은 일반 수용가에 대한 공급 신뢰도를 개선하기 위해서 배전 자동화 시스템을 도입, 실시간 고장구간 탐색 및 계통 재구성을 추진하고 있다. 그러나. 고장 감지기 자체의 오동작이나 통신상의 오류, 다중사고의 가능성 등 불확실성을 포함하고 있기 때문에 비상시 사고구간 추정에 많은 노력과 시간비용이 요구될 수 있다. 따라서. 본 연구에서는 확률론과 휴리스틱 탐색법을 이용하여 배전자동화 시스템에 수집된 정보가 불확실성을 포함하는 경우에도 신속하게 사고 예비 후보 지역을 제시함으로써 고장구간 추정시간을 최소화 할 수 있는 전문가 시스템이 개발된다.

• 한국통신학회논문지
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• 제15권7호
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• pp.581-601
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• 1990

회전기기 이상진단을 해석하는 방법으로 최근까지 여러가지 방법이 제시되고 있다. 본 논문에서는 고차 스펙트럼의 일종인 Bispectrum해석법을 이용하여, 회전기기 요소중의 하나인 베어링의 결함을 진단하는 기법으로서 그 타당성을 검증하고 Bispectrum 해석법의 물리적인 의미를 파악하고자 컴퓨터 시뮬레이션을 행하였다. 컴퓨터 시뮬레이션과 실제의 베어링 결함신호에 대한 결과를 고찰하였으며, 종래의 Power Spectrum보다 베어링 이상진단에 유효함을 알 수 있었다.

• 전기학회논문지
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• 제60권2호
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• pp.285-292
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• 2011

DC traction power system is operated ungrounded so that minimize the stray current. Because the stray current is still present, a rail potential is increased. The ground faults in the DC railway systems are usually detected by a potential relay(64P). Moreover, if the rail potential goes high in the ordinary operating state because of the traction load, the potential relay would be maloperated. A presented protective relaying algorithm that can identify exactly the faulted region and can distinguish a ground fault from the potential rising of the rail is presented in this paper. This paper presents simulation technique that is very similar to the real operation situation using PSCAD/EMTDC.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.192-198
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• 2008

This paper proposes a FRTU-based intelligent fault distance determination strategy in which each FRTU is able to avoid multiple estimations and reduce the level of estimation error by utilizing heuristic rules driven by voltage and current information collected by 1:1 communication with other FRTUs from the same zone in a ubiquitous-based distribution system. In the proposed method, each FRTU, at first, determines a fault zone and a fault path on the faulted zone based on the proposed heuristic rules which use its current data and the voltage data of its neighboring FRTUs as input data. Next, it determines the fault distance from its position based on the fault current estimated from the current data of the neighboring FRTUs. Finally, in order to prove the effectiveness of the proposed method, the diverse fault cases are simulated in several positions of the typical distribution system using the EMTP.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2003

This paper presents a distance relaying algorithm for a transmission line protection with MAS. First, the voltage and fault current of the opposite side are represented as a function of those of the measuring end using source voltages of both ends. These voltages are assumed to be obtained from the transformers protecting agents, periodically in normal state. Then, the fault location expression, independent of fault resistance, is derived with voltage and current in only one end of faulted line used. The suggested algorithm is applied to a simple system with two power sources to show its effectiveness.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2011-2013
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• 2003

The effects of sensor faults on motor variables and control performance in induction motor drives are analyzed by both theoretical approach and simulation study, Vector control and direct torque control method for induction motor are well known. To control speed or position, the informations on rotor speed and rotor or stator flux are required in these control algorithms. The speed is measured by encoder. and the rotor or stator flux is estimated using motor parameters and measured currents. The control input generated based on the information from a faulted sensor should be far from the desired value and deteriorates the overall control performance.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.23-30
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• 2014

This paper presents an on-line diagnosis system for identifying health and faulted conditions in squirrel-cage induction motors using stator current, temperature, and partial discharge signals. The proposed diagnosis system can diagnose induction motor faults such as broken rotor bars, air-gap eccentricities, stator winding insulations, and bearing faults. Experimental results obtained from induction motors show that the proposed system is capable of detecting induction motor faults.

• 조명전기설비학회논문지
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• 제29권8호
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• pp.23-31
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• 2015

This paper proposes an advanced distance relaying based on the DC offset removal filter to minimize the effects of DC offset on a double circuit transmission line. The proposed DC offset removal filter uses only one cycle of data for phasor extraction computation, which does not need to preset the time constant of the DC offset component. This proposed distance relaying uses not only the residual current of the faulted circuit but also mutual current of the healthy adjacent circuit. A series of off-line test results using ATP simulation data show the effectiveness of the an advanced distance relaying.

• 전력전자학회논문지
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• 제9권5호
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• pp.498-506
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• 2004

교류계통에서는 사고가 발생하였을 경우 임피던스를 이용한 거리계전기와 같은 장치로 사고 위치를 파악한다. 하지만 직류계통에서는 주파수 성분이 없기 때문에 회로가 병렬로 연결된 경우에는 정확한 사고위치를 파악할 수가 없다. 전기철도와 같은 시스템에서는 전원으로 직류전압이 사용되고, 이러한 직류계통에서의 사고위치를 파악하기 위한 알고리즘이 필요하게 되었다. 본 논문에서는 전기철도와 같은 직류선로 접지의 보호알고리즘을 제안한다. 전형적인 보호알고리즘과 비교하면 제안된 알고리즘은 공급선로와 고장선로 사이의 차이를 구별하는 장점을 갖는다. 제안된 알고리즘의 내용은 블록킹 필터와 PLC(Power Line Carrier)의 사용에 의해서이다. 시뮬레이션의 결과는 제안된 알고리즘이 매우 유용함을 나타낸다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1057-1058
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• 2007

This paper proposes an alternative vibration detection method in a squirrel-cage induction motor using flux sensors. The air-gap flux will be changed when mechanical vibration occurs by bearing fault as well as broken rotor bar and air-gap eccentricity. For detecting those flux variations due to vibration, search coils are installed at stator slots. The induction motor with 380 [V], 7.5 [kW], 4 [Poles], 1,760 [rpm] ratings is used. Magnitudes and distortion of the induced voltage from flux sensors are used to discriminate faulted types. As a result, the flux sensor has been proven to be useful for vibration detection. It is compared to the result with vibration sensor as well.