Wavelet transform based new methods for voltage flicker signal and harmonic detection

First of all, an improved wavelet transform that can achieve uniform frequency resolution in all frequency bands is demonstrated in this paper. Secondly, a new wavelet synchronous detector for voltage flicker signal detection is proposed. The wavelet synchronous detector, which incorporates synchronous detection with the improved wavelet transform, can detect the abrupt change time, envelope signal and modulating signal of voltage flicker signal accurately, and show the time-frequency characteristics of voltage tucker signal clearly. Thirdly, a novel wavelet comb filter for harmonic detection is put forward. The quadrature mirror filters (QMFs´) are used to realize the improved wavelet transform to implement the novel wavelet comb filter, which can be applied to the detection and time-frequency analysis of short duration harmonics, and can detect all neighboring harmonics and their time-frequency characteristics precisely. Simulation results indicate that the new wavelet synchronous detector and wavelet comb filter can overcome the shortcomings of traditional methods and show excellent performance.