Voltage sags detection based on fundamental frequency vector of generalized S-transform modulus matrixes

This paper proposes a detection method with respect to voltage sags based on the modulus matrix of generalized S-transform. According to the main frequency constituents of the signals, the speed variation rate of Gauss window is determined firstly and then the modulus matrixes of the S-transform is calculated. Based on the S-transform modulus matrixes, the fundamental frequency amplitude vector is extracted, from which the voltage sag amplitude can be acquired. As for sag duration, fundamental frequency difference vector is introduced to detect the sag starting and ending time. Matlab simulation analysis shows that this method is accurate and effective to detect the characteristics of voltage sag and has noise robustness.