The comparisons technique of coefficient DWT for identifying simultaneous fault types on transmission system

Several decision algorithms have been reported in the literature for fault classification, but the effects of simultaneous faults have been neglected. This paper is focused on the decision algorithm for identifying the types of simultaneous fault along the transmission systems using discrete wavelet transform (DWT). The comparison of coefficients DWT has been carried out. DWT is used in order to detect high frequency components of the fault current signals. The coefficient details (phase A, B, C and zero sequence of post-fault current signals) of DWT at the first peak time that positive sequence current can detect fault, are performed as comparison indicator in order to classify fault types. Various cases based on Thailand electricity transmission systems are studied to verify the validity of the proposed algorithm. It is found that the technique proposed in this paper gives satisfactory results to precisely identify simultaneous fault types on transmission systems. © ICIC International 2011.