• Title, Summary, Keyword: Internal fault

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Protection for a Wind Turbine Generator in a Large Wind Farm

  • Zheng, Tai-Ying;Kim, Yeon-Hee;Kang, Yong-Cheol
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.466-473
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    • 2011
  • This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.

Protective Relaying Algorithm for Transformer Using Wavelet Transform (웨이블렛 변환을 이용한 변압기 보호계전 알고리즘)

  • 홍동석;이종범
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.2
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    • pp.134-141
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    • 2003
  • The power transformer is one of the very important electric facilities in power systems. Recently, current differential relay is widely used to protect such power transformer But if inrush occurs in transformer, relay can be tripped by judging like internal fault. Therefore the correct discrimination between internal winding fault, inrush and overexcitation should be performed. This paper presents a new protective relaying algorithm which discriminates inrush, internal faults and overexcitation of transformer modelled using BCTRAN and HYSDAT of EMTP. Discrimination between internal winding fault and inrush is revealed in simulation within 1/2 cycle after fault. Accordingly, it is evaluated that the proposed algorithm has better discrimination characteristics in various cases thin the current relaying for protection of transformer.

KOHONEN NETWORK BASED FAULT DIAGNOSIS AND CONDITION MONITORING OF PRE-ENGAGED STARTER MOTORS

  • BAY O. F.;BAYIR R.
    • International Journal of Automotive Technology
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    • v.6 no.4
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    • pp.341-350
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    • 2005
  • In this study, fault diagnosis and monitoring of serial wound pre-engaged starter motors have been carried out. Starter motors are DC motors that enable internal combustion engine (ICE) to run. In case of breakdown of a starter motor, internal combustion engine can not be worked. Starter motors have vital importance on internal combustion engines. Kohonen network based fault diagnosis system is proposed for fault diagnosis and monitoring of starter motors. A graphical user interface (GUI) software has been developed by using Visual Basic 6.0 for fault diagnosis. Six faults, seen in starter motors, have been diagnosed successfully by using the developed fault diagnosis system. GUI software makes it possible to diagnose the faults in starter motors before they occur by keeping fault records of past occurrences.

Discrimination Method of Internal and External Fault of Current Differential Relay using Instantaneous Value of Current in Case of Fault with One end CT Saturation (편단 CT 포화 고장 발생시 양단 전류 순시치를 이용한 전류차동계전기의 내·외부 고장위치 판별방안)

  • Lee, Myoung-Hee;Choi, Hae-Sul;Kim, Chul-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.12
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    • pp.1801-1806
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    • 2012
  • This paper presents a simple and practical method which enables to prevent malfunction of protection relay due to differential current caused by one end CT saturation in case of external fault. This method uses difference of magnitude(instantaneous value) between the both end current just before the occurrence of differential current without a separate method to CT staturation detection. One end CT saturation is simulated by current transformer model using type-96 component and the presented method is verified by using EMTP MODELS with respect to internal and external fault with one end CT staturation. The presented method distinguished rightly bewteen external and internal fault with one end CT saturation. This information can be used to prevent malfunction of current differential protection relay in case of external fault. And this method is not affected by sampling rate and has no calculation burden, so it will be applicable to differential current protection relay with ease.

Internal Fault Detection and Fault Type Discrimination for AC Generator Using Detail Coefficient Ratio of Daubechies Wavelet Transform (다우비시 웨이브릿 변환의 상세계수 비율을 이용한 교류발전기의 내부고장 검출 및 고장종류 판별)

  • Park, Chul-Won;Shin, Kwang-Chul;Shin, Myong-Chul
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.2
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    • pp.136-141
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    • 2009
  • An AC generator is an important components in producing a electric power and so it requires highly reliable protection relays to minimize the possibility of demage occurring under fault conditions. Conventionally, a DFT based RDR has been used for protecting the generator stator winding. However, when DFTs based on Fourier analysis are used, it has been pointed out that defects can occur during the process of transforming a time domain signal into a frequency domain one which can lead to loss of time domain information. This paper proposes the internal fault detection and fault type discrimination for the stator winding by applying the detailed coefficients by Daubechies Wavelet Transform to overcome the defects in the DFT process. For the case studies reported in the paper, a model system was established for the simulations utilizing the ATP, and this verified the effectiveness of the proposed technique through various off-line tests carried out on the collected data. The propose method is shown to be able to rapidly identify internal fault and did not operate a miss-operation for all the external fault tested.

Transition of voltage-differential current under internal fault on power transformer (전력용 변압기 내부고장시 전압-차전류의 변화에 관한 연구)

  • Park, Jae-Sae
    • Proceedings of the KIEE Conference
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    • pp.92-95
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    • 2004
  • Power transformer is an important apparatus in transforming and delivering the power in a power system. It shows less accident ratio than other system apparatus, but once the accident occurs, it causes long-term operation stoppage and economic loss. It brings high bad spillover effects. Therefore, the role of protective relaying, which is to prevent internal fault a power transformer is highly important. This study proposed advanced algorithm that can clearly determine internal fault of the power transformer and magnetizing inrush, through numerical analysis by using the terminal voltage and input output current.

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Protective Relaying Algorithm for Transformer Using Neuro-Fuzzy (뉴로-퍼지를 이용한 변압기 보호계전 알고리즘)

  • 이명윤;이종범;서재호
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.12
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    • pp.722-730
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    • 2003
  • Current differential relay is commonly used to protect power transformer. However, current differential relay will be tripod by judging like internal fault during inrush occurring in transformer. To resolve such problem, this paper proposes a new protective relaying algorithm using Neuro-Fuzzy Inference. A variety of transformer transition states are simulated by BCTRAN and HYSDT of EMTP. Primary phase voltage and differential current are obtained from simulation. The target data which are used in Neuro-Fuzzy algorithm are obtained from transformed primary voltage and current. Then, these are trained by Neuro-Fuzzy algorithm. The trained Neuro-Fuzzy algorithm correctly distinguishes whether internal fault occurs or not, within 1/2 cycle after fault. Accordingly, it is evaluated that the proposed algorithm has good relaying characteristics.

Internal Fault Classification in Transformer Windings using Combination of Discrete Wavelet-Transforms and Back-propagation Neural Networks

  • Ngaopitakkul Atthapol;Kunakorn Anantawat
    • International Journal of Control, Automation, and Systems
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    • v.4 no.3
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    • pp.365-371
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    • 2006
  • This paper presents an algorithm based on a combination of Discrete Wavelet Transforms and neural networks for detection and classification of internal faults in a two-winding three-phase transformer. Fault conditions of the transformer are simulated using ATP/EMTP in order to obtain current signals. The training process for the neural network and fault diagnosis decision are implemented using toolboxes on MATLAB/Simulink. Various cases and fault types based on Thailand electricity transmission and distribution systems are studied to verify the validity of the algorithm. It is found that the proposed method gives a satisfactory accuracy, and will be particularly useful in a development of a modern differential relay for a transformer protection scheme.

Transformer Protective Relaying Algorithm Using Neuro-Fuzzy based on Wavelet Transform (웨이브렛 변환기반 뉴로-퍼지를 이용한 변압기 보호계전 알고리즘)

  • Lee Myoung Rhun;Lee Jong Beom;Hong Dong suk
    • Proceedings of the KIEE Conference
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    • pp.607-609
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    • 2004
  • A breakdown occurred in power transformer causes interruption of power transmission. Protective relay should be installed in transformer to detect such a fault. Protective relaying algorithm for transformer must be included a function to discriminate between winding fault and inrushing state. Recently, current differential relay is widely used to protect power transformer. However if inrush occurs in transformer, relay can be tripped by judging as internal fault. New algorithms are required in order to such problem. This study proposes a new protective relaying algorithm using Neuro-Fuzzy inference and wavelet. A variety of transformer transient states are simulated by BCTRAN and HYSDT in EMTP. D1 coefficients of differential current are obtained by wavelet transform. D1 coefficients and RMS of 3-phase primary voltage are used to make a target data and are trained by Nwo-Fuzzy algorithm which distinguishes correctly whether internal fault occurs or not within 1/2 after fault detection. It is evaluated that the results obtained by simulations can effectively protect a transformer by contact discriminating between winding fault and inrushing state.

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Numerical Algorithm for Power Transformer Protection

  • Park, Chul-Won;Suh, Hee-Seok;Shin, Myong-Chul
    • KIEE International Transactions on Power Engineering
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    • v.4A no.3
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    • pp.146-151
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    • 2004
  • The most widely used primary protection for the internal fault detection of the power transformer is current ratio differential relaying (CRDR) with harmonic restraint. However, the second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic restraint CRDR must be modified. This paper proposes a numerical algorithm for enhanced power transformer protection. This algorithm enables a clear distinction regarding internal faults as well as magnetizing inrush and steady state. It does this by analyzing the RMS fluctuation of terminal voltage, instantaneous value of the differential current, RMS changes, harmonic component analysis of differential current, and analysis of flux-differential slope characteristics. Based on the results of testing with WatATP99 simulation data, the proposed algorithm demonstrated more rapid and reliable performance.