Flicker representation via STFT and wavelets

Flicker is an important power quality disturbance and has received an increasing concern from power system researchers. Interharmonics are the non-integral frequencies other than harmonic frequencies. Nowadays, research has shown that interharmonics and flicker seem to be closely related. To clarify this relationship, flicker is characterized in the frequency domain. The traditional Fourier-based methods have shown some drawbacks in representing non-stationary, non-periodic power signals and therefore other methods should be investigated for accomplishing this task. This paper introduces two common signal-processing approaches to assess the problem, the short term Fourier transform (STFT) and the wavelet transform. The wavelet transform has shown superior performance to circumvent the problem time-frequency resolution