DETECTION AND ANALYSIS OF POWER QUALITY DISTURBANCE SIGNAL BASED ON DISCRETE COSINE TRANSFORM AND WAVELET TRANSFORM

Synthesizing respective advantages of discrete cosine transform (DCT) and wavelet transform (WT) module maximum in time domain analysis, a DCT and WT based power quality disturbance signal detection method is proposed. In this method firstly the fundamental frequency disturbances, including voltage sag, voltage swell and voltage interruption, and the harmonics in different orders involving transient harmonics are detected, then transient oscillation and transient pulses are detected by use of WT module maximum, and the measurement of duration and amplitude of the disturbances are ascertained. The proposed method possesses better noise proof ability, and its effectiveness is verified by simulation.