Voltage Sag Disturbance Detection Based on Short Time Fourier Transform
Yang Ren-gang · Proceedings of the CSEE · 2007
Short time Fourier transform (STFT) was employed to measure the amplitude of voltage sag, detect interference instant and locate interference source. The amplitude of voltage sag was determined by the amplitude characteristics of fundamental frequency voltage and the high frequency signal produced when voltage sag starts and disappears was employed to identify the voltage sag inception and disappearance instant. A method based on the amplitude of fundamental frequency component and the number of signal singularities is proposed to locate interference source. The method can distinguish the voltage sag induced by fault from that induced by induction motor starting effectively. Simulation tests show that the method has high sensitivity and has better immunity to harmonics and noise than the methods based on wavelet transform.