A novel method for voltage flicker extraction of power systems

In this paper, a null space pursuit (NSP) method based on local narrow band signals is proposed to extract the voltage flicker of the power systems. NSP is the operator-based signal separation approach which constructs an operator from a signal and uses it to separate the signal into two subcomponents, one is the extracted signal in the null space of the operator and the other is the residual. First, the fundamental frequency component is extracted from the voltage waveform of the power systems. Then, the residual signal is demodulated by the fundamental frequency which has been extracted. Finally, we extract the voltage flicker components from the demodulation signal easily. Experiments show that the proposed scheme performs better in terms of suppressing noise and extracting the instantaneous frequency than the Hilbert transform (HT).