• Title/Summary/Keyword: Percentage current differential relay

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A Percentage Current Differential Relaying Algorithm for Bus Protection Blocked by a CT Saturation Detection Algorithm (변류기 포화 곤단 알고리즘으로 억제된 모선보호용 비율 전류차동 계전방식)

  • 강용철;윤재성
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.1
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    • pp.44-49
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    • 2003
  • This paper describes a percentage current differential relaying algorithm for bus protection blocked by a CT saturation detection algorithm. The detection algorithm blocks the output of a current differential relay only if a differential current is caused by CT saturation in the case of an external fault. Moreover, if a current differential relay operates faster than the detection algorithm, the blocking signal is not ignited. On the other hand. if the detection algorithm operates faster than a current differential relay, the output of the relay is blocked. The results of the simulation show that the proposed algorithm can discriminate internal faults from external faults ever when a CT is saturated in both cases. This paper concludes by implementing the algorithm into the TMS320C6701 digital signal processor. The results of hardware implementation are also satisfactory The algorithm can not only increase the sensitivity of the current differential relay but Improve the stability of the relay for an external faults.

Setting Method of a Percentage Current Differential Relay for Transformer Protection (변압기 보호용 전류비율차동 계전기의 동작영역 설정방법)

  • Kim, Su-Hwan;Kang, Sang-Hee
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.1
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    • pp.8-13
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    • 2011
  • A percentage current differential relay is widely used for transformer protection. Because many percentage current differential relays recently use modified methods instead of conventional methods for deciding the operating characteristics of the large current region, in this paper, the operating region of a percentage current differential relay is analyzed in input-output current domain instead of operating-restraint current domain. An effective method to set the operating region when a CT is saturated is proposed with a series of investigations comparing a conventional method with the proposed modified method. The performance of the proposed method is evaluated for internal and external faults of a power transformer having the voltage rating of 345/154kV. EMTP-RV is used for the relaying data collection.

A Percentage Differential Current Relaying Algorithm for Bus Protection Using Current Transformer Saturation Detecting Algorithm (변류기 포화검출 알고리즘을 적용한 모선보호용 비율전류차동 계전방식)

  • Kang, Yong-Cheol;Yun, Jae-Sung;Ok, Seung-Hun
    • Proceedings of the KIEE Conference
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    • 2001.11b
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    • pp.115-117
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    • 2001
  • A percentage current differential relaying algorithm is widely used for bus protection. However, it may maloperate external faults with CT saturation. This paper proposes a percentage current differential relaying algorithm for bus protection using CT saturation detecting algorithm. The CT saturation detecting algorithm uses difference of secondary current of CT and detects CT saturation. The proposed method distinguishes percentage differential relay operation caused by faults from percentage differential relay operation caused by CT saturations.

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A Percentage Current Differential Relaying Algorithm for Bus Protection Using an Advanced Compensating Algorithm of the CTs (개선된 변류기 보상알고리즘을 적용한 모선보호용 비율전류차동 계전방식)

  • 강용철;윤재성;강상희
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.3
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    • pp.158-164
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    • 2003
  • This paper proposes a percentage current differential relaying algorithm for bus protection using an advanced compensating algorithm of the secondary current of current transformers (CTs). The compensating algorithm estimates the core flux at the start of the first saturation based on the value of the second-difference of the secondary current. Then, it calculates the core flux and compensates distorted currents using the magnetization curve. The algorithm Is unaffected by a remanent flux. The simulation results indicate that the proposed algorithm can discriminate internal faults from external faults when the CT saturates. This paper concludes by implementing the algorithm into a TMS320C6701 digital signal processor. The results of hardware implementation are also satisfactory. The proposed algorithm can improve not only stability of the relay in the case of an external fault but sensitivity of the relay in the case of an internal fault.

A Fault Analysis Program for a Digital Bus Protection Relay (모선보호용 디지털계전기의 고장분석 프로그램의 구현)

  • Son, Chun-Myung;Kang, Sang-Hee;Lee, Seung-Jae;Ahn, Yong-Jin
    • Proceedings of the KIEE Conference
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    • 2001.11b
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    • pp.246-248
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    • 2001
  • In this paper, the fault analysis program that is convenient to analyse fault records of a digital relay and to set a digital relay is described. The key feature of this fault analysis program is as follows. - analysing fault records stored in a local PC and/or a digital relay - analysing events - setting a digital relay. This program is for a digital bus protection relay using a conventional variable percentage current differential relaying algorithm. So this program adds a function analysing the characteristic of each variable percentage current differential function and the connection state of the transmission lines at double-bus system.

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A Percentage Current Differential Relay for Bus Protection Using a Compensation Algorithm Unaffected by a Remanent Flux (잔류자속에 무관한 보상 알고리즘을 적용한 모선보호용 전류차동 계전방식)

  • Kang, Yong-Cheol;Yun, Jae-Sung;Lim, Ui-Jai
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.308-310
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    • 2003
  • This paper proposes a percentage current differential relaying algorithm for bus protection with a compensation algorithm of a CT. The compensating algorithm estimates the core flux at the start of the first saturation based on the value of the third-difference of the secondary current. It calculates the core flux and compensates distorted currents in accordance with the magnetization curve. The test results indicate that the algorithm can discriminate internal faults from external faults when the CT saturates. It can improve not only stability of the relay in the case of an external fault but sensitivity of the relay in the case of an internal fault.

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Digital Relaying Algorithm for Power Transformer Protection using Fuzzy Logic Approach

  • Park, Chul-Won;Shin, Myong-Chul
    • KIEE International Transactions on Power Engineering
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    • v.2A no.4
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    • pp.153-159
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    • 2002
  • Power transformer protective relay should block the tripping during magnetizing inrush and rapidly operate the tripping during internal faults. Recently, the frequency environment of power system has been made more complicated and the quantity of 2nd frequency component in inrush state has been decreased because of the improvement of core steel. And then, traditional approaches will likely be maloperate in the case of magnetizing inrush with low second harmonic component and internal faults with high second harmonic component. This paper proposes a new relaying algorithm to enhance the fault detection sensitivities of conventional techniques by using a fuzzy logic approach. The proposed fuzzy based relaying algorithm consists of flux-differential current derivative curve, harmonic restraint, and percentage differential characteristic curve. The proposed relaying was tested with relaying signals obtained from EMTP simulation package and showed a fast and accurate trip operation.