• 제목/요약/키워드: Relaying Signals

검색결과 74건 처리시간 0.022초

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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    • 제2A권4호
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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.

프로니해석법을 이용한 공진 주파수 검출 알고리즘 (Oscillation Frequency Detecting Technique for Transmission Line Protection using Prony's Analysis)

  • 조경래;김성수;박종근;홍준희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1995년도 하계학술대회 논문집 B
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    • pp.509-512
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    • 1995
  • The relaying algorithm to calculate the fault distance from only transient signal at faults in T/L is presented. In this paper. At faults the oscillation frequency components exist in both voltage and current and these components minimize the input impedance shown in fault point. The equivalent source impedance shown in relaying point is needed to calculate the fault distance using these components. To source impedance, the reflection coefficient between forward wave and backward and the Prony's analysis is also employed to extract the oscillation frequency component from transient signals. The case study show that the new distance relaying algorithm satisfies the high operation speed and high accuracy even if the algorithm uses only transient signals.

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환상형 분산전원 단지 보호를 위한 전압제어 과전류 계전기 (Voltage-controlled Over-current Relay for Loop-connected Distributed Generators)

  • 김태희;강상희
    • 전기학회논문지
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    • 제65권12호
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    • pp.1979-1985
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    • 2016
  • A protection algorithm using a voltage-controlled overcurrent element for a looped collection circuit in a wind farm is suggested in this paper. Because the proposed algorithm uses voltage relaying signals as well as current relaying signals, any fault in the looped collection circuit can be cleared by voltage-controlled overcurrent relays located at the two adjacent relaying points, the nearest place in each direction from the fault point. The algorithm can also distinguish the external faults which occur at the outside of a wind farm from the internal faults. It means that the proposed algorithm can provide the proper ability of protection coordination to the relays in the looped collection circuits of a large wind farm. The performance of the proposed algorithm is verified under various fault conditions using PSCAD/EMTDC simulations.

신경회로망을 이용한 과도파형의 기본파성분 추출에 관한 연구 (A Study on the Extraction of Fundamental Frequency Components in the Transient Wave Signals Using Artificial neural networks)

  • 신명철;이복구
    • 대한전기학회논문지
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    • 제43권4호
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    • pp.553-563
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    • 1994
  • This paper presents a filtering method using neural networks to extract fundamental frequency components of the transient wave signals in power systems. Based on the ability of multilayer feedforward neural networks to approximate any continuous function, a neural networks mapping filter is proposed for the protective distance relaying systems to extract the effective components efficiently. A characteristic feature of this mapping filter is composed of the multilayer perceptron neural networks which are trained by using random signals and those are mapped to the DFT filtering computational structure by GDR(Generalized Delta Rule). The advantage of this approach is demonstrated by the random waves and the fault transient wave signals of EMTP(electromagnetic transients program) in power systems fault conditions. The proposed method is compared with the conventional method and the simulation results show the efficiency of the neural networks.

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2회선 송전선로의 새로운 디지털 평형계전방식 (A New Digital Balance Relaying Technique in Two Parallel Transmission Lines)

  • 권기백;박철원;정호성;신명철;박재세;남시북
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 하계학술대회 논문집 D
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    • pp.1028-1031
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    • 1997
  • This Paper Presents a new digital balance relaying technique in two Parallel transmission lines. To obtain relaying signals, selected model is simulated using EMTDC. Test results of the proposed method show efficacy.

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고장저항의 영향을 최소화한 거리계전기법 (A Digital Distance Relaying Algorithm Immune to Fault Resistance)

  • 안용진;강상희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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    • pp.286-288
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    • 1998
  • A digital distance relaying algorithm immune to the effect of the fault resistance in single-phase to ground fault is proposed. The power frequency components of relaying signals are extracted by the 1 cycle DFT. To compensate the magnitude and phase of the estimated impedance, which is calculated by the general method, this algorithm uses phase difference between the zero sequence impedance of networks on both sided of the system.

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최소자승법을 이용한 고속 거리계전 알고리즘 (A High Speed Distance Relaying Algorithm Based on a Least Square Error Method)

  • 권태원;강상희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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    • pp.208-210
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    • 1998
  • A high speed digital distance relaying algorithm based on a modified least square error method is proposed. To obtain stable phasor values very Quickly, first, a lowpass filter which has very short transient period and no overshoot is used. Secondly, the conventional least square error method is modified to the one having the data window of 3 samples by applying a FIR filter which removes the DC-offset component in current relaying signals.

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대용량 변압기 보호용 퍼지논리 계전기법과 웨이브렛 계전기법의 비교 분석 (A Comparative Analysis of Fuzzy Logic-Based Relaying and Wavelet-Based Relaying for Large Transformer Protection)

  • 박철원;박재세;신명철
    • 전기학회논문지P
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    • 제52권4호
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    • pp.179-188
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    • 2003
  • Percentage differential characteristic scheme has been recognized as the principal basis for large transformer protection. Nowadays, relaying signals can contain second harmonic component to a large extent even in a normal state, and second harmonic ratio indicates a tendency of relative reduction because of the advancement of transformer's core material. And then, conventional second harmonic restraint differential relaying exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for the effective and accurate discrimination. This paper deals with advanced fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush. The proposed fuzzy relaying and a new fault detection scheme were tested. The former, fuzzy relaying, was proven to be faster and more reliable than the latter.

전압-전류 추이와 자속-차전류 기울기 특성을 이용한 변압기 보호계전기법의 성능 개선 (Performance Improvement of Protective Relaying for Large Transformer by Using Voltage-Current Trend and Flux-Differential Current Slope Characteristic)

  • 박철원;박재세;정연만;하경재;신명철
    • 전기학회논문지P
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    • 제53권2호
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    • pp.43-50
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    • 2004
  • Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the proposed algorithm, we have made comparative studies of PDR, fuzzy relaying and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP, and data collection is made through simulation of various internal faults and inrush. As the results of test, the new proposed algorithm was proven to be faster and more reliable.

Power allocation for full-duplex NOMA relaying based underlay D2D communications

  • Li, Song;Li, Shuo;Sun, Yanjing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제13권1호
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    • pp.16-33
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    • 2019
  • In this paper, a full-duplex NOMA relaying based underlay device-to-device (D2D) communication scheme is proposed, in which D2D transmitter assists cellular downlink transmission as a full-duplex relay. Specifically, D2D transmitter receives signals from base station and transmits the superposition signals to D2D receiver and cellular user in NOMA scheme simultaneously. Furthermore, we investigate the power allocation under the proposed scheme, aiming to maximize D2D link's achievable transmit rate under cellular link's transmit rate constraint and total power constraint. To tackle the power allocation problem, we first propose a power allocation method based on linear fractional programming. In addition, we derive closed-form expressions of the optimal transmit power for base station and D2D transmitter. Simulation results show that the performance of two solutions matches well and the proposed full-duplex NOMA relaying based underlay D2D communication scheme outperforms existing full-duplex relaying based D2D communication scheme.