Detection of Transient Power Quality Based on db4 Lifting Wavelet

Transient disturbances are one of the most important factors it influence power quality in power system,and do harm to the power system and power users.According to non-stationary and burst capability of the transient disturbing signals,this paper analyzes the characteristics of db4 lifting wavelet transient,proposes a structure,containing update-predict-update-predict-update,choses the appropriate sampling frequency and decomposition level,to detect and locate the transient power quality disturbances.In the MATLAB environment,the db4 lifting wavelet transient is used for detection and location on the voltage sags,voltage swells,voltage interruption,transient pulse,transient oscillation and other transient power quality disturbing signals.Simulation results indicates that the method has a millisecond level accuracy and can be implemented precisely positioning on starting and ending time of the disturbance signals,and with high calculation speed.