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Author: search.filters.author.Apisit, ChaowatSubject: search.filters.subject.Discrete wavelet transforms

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    Algorithm improvement to predict fault location of simultaneous fault in underground cable
    (2013-11-11)
    Apisit, Chaowat
    ;
    Ngaopitakkul, Atthapol
    In the literature for fault location, most of research works have never been mentioned about effects of simultaneous faults. This paper presents a new decision algorithm that will be developed in order to predict precisely fault location, during simultaneous fault, in an underground distribution system using discrete wavelet transform (DWT). The advantage of the DWT is that the band of analysis can be fine adjusted so that high frequency components and low frequency components are detected precisely, consequently DWT is considered herein. The fault signal is simulated using ATP/EMTP. The DWT is used to detect the high frequency components. Coefficients of positive sequence current signals are calculated. The positive sequence current as extracted to several scales with the DWT, and the coefficients of the first scale from the DWT are investigated. The time that the fault signal uses to reach the ends of the distribution line is considered, then, applied so that the distance of fault can be calculated. Various case studies have been carried out including the single fault and simultaneous fault. The result is found that the proposed algorithm gives satisfactory both in case of single fault and simultaneous fault. © 2013 The Institute of Electrical Engineers of Japan.
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    Behavior of interturn fault in transformer windings using discrete wavelet transform
    (2010-12-01)
    Jettanasen, Chaiyan
    ;
    Ngaopitakkul, Atthapol
    ;
    Apisit, Chaowat
    In the literature for fault detection, most of research works have never been mentioned about the transformer models with the high frequency model including capacitances of the transformer. This paper presents behaviour of winding to ground fault signals in a three-phase two-winding transformer. The advantage of the discrete wavelet transform (DWT) is that the band of analysis can be fine adjusted so that high frequency components and low frequency components are detected precisely; that is why discrete wavelet transform is herein considered. The fault is simulated using ATP/EMTP and the behaviour analysis of signals is performed using DWT. The variation of high frequency components of differential current signals is proposed in this paper. The results obtained from the analysis will be useful in the development of a detect fault scheme for power transformer in the future.
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    Study of characteristics for simultaneous faults in electrical power systems based on wavelet transform
    (2010-12-01)
    Ngaopitakkul, Atthapol
    ;
    Apisit, Chaowat
    In the literature for fault detection, most of research works have never been mentioned about effects of simultaneous faults. This paper presents behaviour of characteristics for simultaneous fault signals in a 500-kV electrical power transmission system using wavelet transform. The fault signal is simulated using PSCAD/EMTDC and the behavior analysis of signals is performed using discrete wavelet transform (DWT). The DWT is used in order to detect the high frequency components. The results obtained from the analysis will be useful in the development of a detect fault scheme for electrical transmission line in the future due to an effect of the other fault that occurs at the other side of the system (bus NCO) leading to the malfunction of the protective relays.
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    Behavior of winding to ground fault in transformer windings using discrete wavelet transform
    (2010-12-01)
    Pothisarn, Chaichan
    ;
    Ngaopitakkul, Atthapol
    ;
    Pongchaisrikul, Worravut
    ;
    Apisit, Chaowat
    ;
    Jonpermpoonpol, Saridroje
    In the literature for fault detection, most of research works have never been mentioned about the high frequency transformer including capacitances. This paper presents behaviour of winding to ground fault signals in a three-phase two-winding transformer. The advantage of the discrete wavelet transform (DWT) is that the band of analysis can be fine adjusted so that high frequency components and low frequency components are detected precisely, consequently DWT is considered herein. The fault is simulated using ATP/EMTP and the behaviour analysis of signals is performed using DWT. The variation of high frequency components of differential current signals is proposed in this paper. The results obtained from the analysis will be useful in the development of a detect fault scheme for power transformer in the future.