The research of power quality analysis based on improved S-Transform

The paper proposes improved S-transform (IST) to detect and classify power quality (PQ) disturbances with time-domain analysis. First, the theory of S-transform (ST) is introduced. To enhance the analytic power of ST in different non-stationary signal processing, IST is achieved by adding an adjustable factor to the Gaussian window function of the normal ST. The adjusted factor changes the velocity in which the width of the window function varies inversely with the frequency. IST possesses an adjustable time-frequency resolution and higher practicability and adaptability than ST in the actual application. IST analysis performed on the PQ disturbance signals can identify the magnitude and duration of the disturbances. The comparison between the wavelet-transform-based method and the improved S-transform-based method for power quality disturbance recognition is also provided. The simulation results show that the proposed method is effective and immune against noise. The proposed method is feasible and promising for practical applications.