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Author: search.filters.author.Pothisarn, C.Subject: search.filters.subject.Discrete Wavelet Transform

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    Improvement to reduce training time of back-propagation neural networks for discrimination between external short circuit and internal winding fault
    (2014-11-05)
    Bunjongjit, S.
    ;
    Ngaopitakkul, A.
    ;
    Pothisarn, C.
    ;
    Jettanasen, C.
    This paper proposes the improvement technique to reduce training time of back-propagation neural network. The decision algorithm based on the hybrid of discrete wavelet transform (DWT) and back-propagation neural network (BPNN) has been proposed to classify between external fault and internal fault in power transformer. The DWT is employed to decompose high frequency component of post-fault differential current signals and used as an input pattern for the training process of a neural network in a decision algorithm with a use of the BPNN. The proposed technique is compared with conventional training process of BPNN in terms of average accuracy and training time process. The obtained results show that the proposed technique can reduce of training process duration time and is very effective in classifying between external fault and internal fault in power transformer with satisfactory accuracy.
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    A discrete wavelet transform and fuzzy logic algorithm for identifying the location of fault in underground distribution system
    (2013-01-01)
    Bunjongjit, S.
    ;
    Ngaopitakkul, A.
    ;
    Pothisarn, C.
    This paper proposes the hybrid decision algorithm of discrete wavelet transform (DWT) and fuzzy logic in order to identify the location of fault in underground distribution cable. The high frequency component obtained from DWT with the mother wavelet daubechies4 (db4) is used as an index for the occurrence of faults. The first peak time of DWT, obtained from positive sequence that can detected the occurrence of faults are considered as an input pattern of decision algorithm. The obtained average accuracy results have shown that the proposed decision algorithm is able to identify the location of fault with satisfactory accuracy. © 2013 IEEE.
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    Analysis of characteristics using wavelet transform for simultaneous faults in electrical power system
    (2012-12-12)
    Pothisarn, C.
    ;
    Ngaopitakkul, A.
    This paper presents an analysis of characteristics for simultaneous fault signals in a 500-kV electrical power transmission system using wavelet transform. Such fault signals can occur in the transmission system, and have an effect to the operation of distance relays installed in the system. The fault analysis is performed using PSCAD/EMTDC. The Discrete Wavelet Transform (DWT) is used in order to detect the high frequency components. In addition, characteristics of fault current at various fault inception angles, fault locations and faulty phases are detailed. It has been found that when applying the previous decision algorithm give a wrong conclusion of fault types and fault location. © 2012 IEEE.