Optimal Daubechies' wavelet bases for detection of voltage sags in electric power distribution and transmission systems

Wavelet analysis of voltage sag completely depends on the choice of the wavelet basis. For better detection performance via wavelet analysis, the choice of the optimal wavelet basis must be provided within the constraints of the uncertainty principle which restricts arbitrary assignment of time-frequency resolution. In this paper, we describe local properties of the wavelet basis and voltage sag signal in terms of time duration and frequency bandwidth parameters. After comparison of the local properties of the wavelet basis and voltage sag signal, we suggest a set of performance indexes to measure the time-frequency resolution relation between the wavelet basis and the voltage sag signal. This procedure of determining the optimal wavelet basis can be extended to other possible applications of wavelets.