• 제목/요약/키워드: Internal fault Inrush

검색결과 46건 처리시간 0.021초

잔류자속에 무관한 변압기 보호용 수정전류차동 계전기 (Modified Current Differential Relay for Transformer Protection Unaffected by Remanent flux)

  • 강용철;김은숙
    • 대한전기학회논문지:전력기술부문A
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    • 제53권9호
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    • pp.500-506
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    • 2004
  • This paper proposes a modified current differential relay for transformer protection unaffected by the remanent flux. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. To cope with the remanent flux, before saturation, the relay calculates the core-loss current and uses it to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the actual core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

Dempster 결합룰에 의한 전력용 변압기 외란상태판정 (Disturbance State Identification of Power Transformer Based on Dempster's Rule of Combination)

  • 강상희;이승재;권태원;김상태;강용철;박종근
    • 대한전기학회논문지:전력기술부문A
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    • 제48권12호
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    • pp.1479-1485
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    • 1999
  • This paper proposes a fuzzy decision making method for power transformer protection to identify an internal fault from other transient states such as inrush, over-excitation and an external fault with current transformer (CT) saturation. In this paper, analyzing over 300 EMTP simulations of disturbances, four input variables are selected and fuzzified. At every sampling interval from half to one cycle after a disturbance, from the EMPT simulations, different fuzzy rule base is composed of twelve if-then fuzzy rules associated with their basic probability assignments for singleton- or compound-support hypotheses. Dempster's rule of combination is used to process the fuzzy rules and get the final decision. A series of test results clearly indicate that the method can identify not only an internal fault but also the other transients. The average of relay operation times is about 12(ms). The proposed method is implemented into a Digital Signal Processor (TMS320C31) and tested.

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비선형 자화특성을 고려한 3상 변압기 보호용 전류차동 계전방식 (A Current Differential Relaying Algorithm for Three-Phase Transformer Considering the Nonlinear Magnetization Characteristics of the Core)

  • 강용철;김은숙;원성호;임의재;강상희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 하계학술대회 논문집 A
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    • pp.320-322
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    • 2003
  • This paper describes a current differential relaying algorithm for a three-phase transformer considering the nonlinear magnetization characteristics of the core. The iron-loss current is obtained from the calculated induced voltage and the core-loss resistance. The magnetizing current is calculated from the estimated core flux and the magnetization curve. The proposed algorithm uses the modified differential current, which is obtained by subtracting the iron-loss current and the magnetizing current from the conventional differential current. The various test results show that the algorithm can discriminate internal fault from magnetic inrush, overexcitation and an external fault.

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잔류자속에 무관한 전류보상 알고리즘을 적용한 변압기 보호용 전류차동 계전방식 (A Current Differential Relaying Algorithm for Power Transformers Using an Advanced Compensation Algorithm of CTs)

  • 강용철;임의재;윤재성;김은숙;원성호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 하계학술대회 논문집 A
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    • pp.314-316
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    • 2003
  • To prevent maloperation during magnetic inrush and over-excitation, a current differential relay for power transformers uses harmonic current based restraining or blocking scheme; it also uses dual slope characteristics to prevent maloperation for an external fault with CT saturation. This paper proposes a current differential relaying algorithm for power transformers with an advanced compensation algorithm for the secondary current of CTs. The comparative study was conducted with and without the compensating algorithm. The algorithm can reduce the operating time of the relay in the case of an internal fault and improve security for external faults.

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Fuzzy Decision-Making을 이용한 지능형 변압기 보호 계전 알고리즘 (An Intelligent Power Transformer Protective Relaying Algorithm Based on Furzy Decision-Making)

  • 이승재;강상희;최면송;김상태;강대훈;김기화;김일동;장병태;임성일
    • 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.

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보상 알고리즘을 적용한 변압기 보호용 전류차동 계전방식 (Current Differential Relaying Algorithm for Power Transformer Protection Operating in Conjunction with a CT Compensating Algorithm)

  • 강용철;박종민;이미선;장성일;김용균;소순홍
    • 전기학회논문지
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    • 제56권11호
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    • pp.1873-1878
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    • 2007
  • Current differential relays may maloperate during magnetic inrush and over-excitation because a significant differential current is produced. To prevent maloperation, the relays adopt some harmonic components included in the differential current. The harmonic restraints may increase the security of a relay but cause the operating time delay of a relay when an internal fault occurs. Moreover, the operating time delay is more increased if a current transformer (CT) is saturated. This paper describes a current differential relaying algorithm for power transformer protection with a compensating algorithm for the secondary current of a CT. The comparative study was conducted with and without the compensating algorithm. The performance of the proposed algorithm was investigated when the measurement CT (C400) and the protection CT (C400) are used. The proposed algorithm can compensate the distorted current of a CT and thus reduce the operating time delay of the relay significantly for an internal fault with CT saturation.

Fuzzy Logic Based Relaying Using Flux-differential Current Derivative Cure for Power Transformer Protection

  • 권명현;박철원;서희석;이복구;신명철
    • 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.

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전압, 전류 변화 추이를 이용한 전력용 변압기 보호계전 알고리즘 (A New Protective Relaying Algorithm for Power Transformer Based on Three Phase Voltage and Current)

  • 김상태;이승재;강상희;진보건;윤상현;이태성
    • 대한전기학회논문지:전력기술부문A
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    • 제50권4호
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    • pp.157-165
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    • 2001
  • The two criteria to identify the disturbances of the power transformer has been reported in this paper. They have been derived through EMTP simulations of internal faults, inrush and overexcitation for the model of 154/22.9[kV], 40[MVA], Y-Y three-phase power transformer. We propose the crisp algorithm which uses two criteria. A series of test results clearly indicate that the method can identify not only an internal fault but also the other transients. The average of relay operation times is about 7.2[ms]. The proposed algorithm immunes to the transient state.

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잔류자속을 고려한 변압기 보호용 수정 전류차동 계전방식 (A Modified Current Differential Relaying Algorithm for Transformer Protection Considered by a Remanent Flux)

  • 강용철;김은숙;원성호;임의재;강상희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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    • pp.262-265
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    • 2003
  • During magnetic inrush or over-excitation saturation of the core in a transformer draws a large exciting current. This can cause mal-operation of a differential relay. This paper proposes a modified current differential relay for transformer protection. In order to cope with the remanent flux at the beginning. the start of saturation of the core is detected and the core flux at the instant is estimated by inserting the differential current into a magnetization curve. Then, this core flux value can be used to calculate the core flux. The proposed relay calculates the core-loss current from the induced voltage and the core-loss resistance; the relay calculates the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss current and the magnetizing current from the conventional differential current. The proposed technique not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the speed of the conventional relay.

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Y-$\Delta$ 변압기 보호용 수정 전류차동 계전기 (Modified Current Differential Relay for Y-$\Delta$ Transformer Protection)

  • 강용철;김은숙;이병은
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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    • pp.9-13
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    • 2004
  • This paper proposes a modified current differential relay for Y-$\Delta$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. The relay correctly discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

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