The denoising of power quality disturbance is an important subject for power quality monitoring and analysis. With the integration of nonlinear and rapid loads, power quality disturbance may present non-stationary behavior in power electronic systems. By analyzing the energy distribution of power quality disturbance, an improved denoising algorithm based on the fractional Fourier transform is proposed. Meanwhile, estimation algorithm of the optimal transform angle is also analyzed. The fourth order origin moment of fractional spectrum is employed to reduce the computational complexity. Compared to the wavelet-based method, the proposed algorithm can achieve better performance for both transient disturbance and chirp disturbance. Simulation results verify the effectiveness of the proposed algorithm.

Chirp disturbance,Denoising,Fractional Fourier transform,Optimal transform angle,Power quality