Bus Differential Protection Based on Wavelet Packet Transform
When TA saturation happens,the bus big differential current waveforms have serious distortion. It is difficult for the traditional principle of full current bus differential protection to determine faults within or outside the buses. Based on principles of wavelet packet transform a new method for bus differential protection is proposed in this paper. By using the method of wavelet packet transform on the big differential currents,extracting high-frequency coefficients of wavelet packet,to decide faults within or outside the buses. A large number of simulation results show that the principle of bus differential protection is correct and reliable.