A wavelet-based restricted earth-fault power transformer differential protection

Abstract This paper proposes a restricted earth fault protection based on the wavelet transform (REFW) for detecting ground faults close to the transformer neutral point (turn-to-ground faults) and supporting the conventional phase differential protection, which presents limitations in this kind of faults. The proposed REFW protection uses only high-frequency components instead of phasor estimation, speeding up the detection of turn-to-ground faults. A performance comparison between the proposed wavelet-based restricted earth-fault differential protection and the respective conventional restricted earth-fault (REF) unit was accomplished considering simulated turn-to-ground faults, involving a few winding turns. The proposed method is more efficient and faster than the conventional one, reaching a success rate of 100%.

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