• 한국지능시스템학회논문지
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• 제8권5호
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• pp.72-82
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• 1998

Power transformer protective relay should block the tripping during magnetizing imrush and rapidly operate the tripping during internal faults. But traditional approaches maloperate in the case of magnetizing inrush with low second harmonic component and internal faults with high second harmounic component. To enhance the fault detection sensitivities of conventional technuques, flux-differential current derivative curve by fuzzy theory approaches is used. This paper deals with fuzzy logic based protective relaying for power transformer. The proposed fuzzy based relaying algorithm consisits of flux-differential current derivative curve, harmonics restraint, and precentage differential characteristic curv. The proposed relaying was tested with relaying signals obtained from Salford EMTP simulation package and showed a fast and accurate trip operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.365-367
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• 2005

This paper proposes a hardware of IED for power transformer protection that is well constructed using DSP chip and MPU chip. The performance of the adaptive relaying algorithm, by real-time testing in a prototype of it, has been verified. And test results indicate the proposed relaying of the IED was proven to be faster and more reliable.

• 전기학회논문지P
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• 제63권4호
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• pp.295-300
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• 2014

The frequency is an important operating parameter of a power system. There is an increasing importance of constant monitoring of frequency to achieve stable power supply by WAMS(wide area monitoring system) and FNET(Frequency Monitoring Network). This paper is part of development of a network-based frequency monitoring and failure prediction system for wide-area intelligent protection relaying. In this paper, analysis of propagation speed of power frequency by generation drop using the PSS/E was carried out. For dynamic analysis, the 11 metropolitan areas offices of KEPCO divided into five groups of Seoul, Gangwon, Chungcheong, Honam, and Yeongnam group, study was performed.

• 한국지능시스템학회논문지
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• 제9권5호
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• pp.538-544
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• 1999

본 논문에서는 송전선로의 보호를 위하여 적응형 퍼지 시스템을 도입하여 고장 유형 판별부와 고장점 추정부의 두 부분으로 구성된 새로운 고장검출기법을 개발하였다. 제안된 시스템의 퍼지 입력변수로는 전류의 정상분과 영상분 그리고 실효치를 선정하였으며 신경회로망의 학습방법에 의하여 전건부와 후건부가 적절하게 조정되었다. 제시된 기법의 효용성을 입증하기 위하여 전자과도 해석 프로그램인 EMTP로부터 수집된 데이터를 활용하였다. 시뮬레이션 결과 제안된 기법은 고장유형이 정확하게 판별되었으며 고장점 추정이 개선되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.122-127
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• 2005

This paper proposes a prototype IED hardware design and it's real-time experimental results. To evaluate performance of the IED, the study is well constructed power system model including power transformer utilizing the EMTP software and the testing is made through simulation of various cases. The relaying that is well constructed using DSP chip and RISC CPU etc. has been developed and the prototype IED has been verified through on-line testing by LabVIEW simulator. The results show that an advanced relaying based prototype IED never mis-operated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.268-270
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• 2003

This paper proposes a software design and hardware implementation of Intelligent Electronic Device(IED) for power transformer. The relaying algorithm is based on DFT. The protection functions implemented include RDR with a second harmonic restraint for magnetizing inrush, OCR, OCGR, OVR, and UVR etc. The main board of IED is based on the TMS32C32 Processor. The IED was tested with relaying signals obtained for EMTP simulation package.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2281-2283
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• 1998

In this paper, we propose a digital differential protection of power transformer using intelligent schemes. Intelligent schemes is based on fuzzy logic and neural networks. To enhance the distinction between fault and inrush of conventional approaches, relaying technique by fuzzy logic and neural networks are used. We used transformer inrush currents, external and internal fault signals, which are obtained from EMTP simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.517-519
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• 2005

In this paper, we consider a digital protection IED(Intelligent Electric Device) for a distributed power system. The IED can measure various elements for protection and communicate with another devices through network. The protection IED is composed of specific function modules: signal process module which converts analog signal from PT and CT handle algorithm to digital one; communication module for connection with another IEDs; input/output module for user-interfaces. A general purpose DSP board with TMS320C2812 is used in the IED. In order to verify the proposed IED, experimental researches with the power system simulator DOBLE has been carried out for a phase earth fault. The results show an under-voltage relaying algorithm has been realized sucessfully in the hardware system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1094-1096
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• 1998

An intelligent power transformer protective relaying algorithm based on fuzzy decision-making is proposed. To distinguish external faults with CT saturation, overexcitation and inrush conditions from internal faults, a newly designed fuzzy-rule base is used. The Dempster-Shafer's rule of combition is used for fuzzy inference. A series of the S/W and H/W tests show the proposed protection algorithm has practically sufficient sensitivity and selectivity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.891-893
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• 1997

In this paper an intelligent power transformer protective relaying algorithm based on Fuzzy Decision-Making is presented. The introduced protection algorithm contains several internal fuzzy rule-bases including bpa(Basic Probability Assignment: m) which are subject to off-line pre-installation by the analysis of the transformer transient characteristics for detecting the internal fault. Dempster-Shafer's rule of combination is used for the inference method with rules to decide the situation of a transformer, The proposed algorithm immunes to the saturation of transformer, inrush conditions, over excitation, and external fault. The included results of testing show practically sufficient sensitivity and selectivity of the proposed algorithm.