Discrimination of transformer inrush current and inner short circuit current with wavelet energy spectrum diagrammatic method
Qi Hui · Relay · 2004
How to identify transformer inrush current is a main problem to transformer relay. Based on the wavelet and multi-resolution theory, a new method is proposed to construct the protection judgment to discriminate the inrush current and internal fault by the ratio of high frequency segments in different scales of energy spectrogram.This method extracts the feature values from the energy spectrogram of the signal transformed by wavelet,and with these values,it can identify inrush current from internal short circuit current. Simulation results show that this new method is brief, effective, and applicable in practice.