Abstract:  The quantificational detection for the change of voltage amplitude was investigated in this paper．First‚two conceptions were defined‚that is‚the amplitude and adjusting amplitude based on two real wavelet standard trans-forms．Next‚it was proved that‚if the two real wavelets meet some conditions‚and one is an even function and the other is an odd one‚the adjusting amplitudes based on the two real wavelet standard transforms are always equal to1in the wel- l balanced duration‚while the adjusting amplitudes are equal to the ratio of vo- l tage amplitude in the wel- lbalanced duration to that in the disturbance duration．Finally‚the adjusting amplitudes of two selected real wavelets were used to detect the voltage waveform aberrance．Simulated results show that the novel amplitude detection figures can not only find accurately out the start point and stop point of faults but also quantitatively display the changing mag-nitude of voltage.

Key words:  wavelet transform, signal detection, power quality