A new DC feeder protection based on wavelet transform

This paper presents a new DC feeder protection based on wavelet transform. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The remote short-circuit current is determined mainly by the steel rail impedance, which is time varying due to the skin effect. In contrast, impedances of the traction motor and the contact wires, and the change of operating mode during starting govern the train starting current. The wavelet transform identifies these salient features. The remote short-circuit current and train starting current are simulated using SIMULlNK. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of short circuit current and the train starting current, more effective algorithms such as wavelet transform has been proposed.