Research of traveling-wave differential bus protection based on wavelet transform

To avoid the adverse effect of current transform (CT) transient saturation, this paper studies a novel bus protection based on transient current traveling-waves. Firstly the paper presents the differential traveling-wave (DTW) for each phase of circuits connected to the protected bus. The DTW fault features are analyzed. Then in order to distinguish more sensitively between faults internal and external to the bus, the restraint traveling-wave is introduced into the DTW. Thus the paper proposes the bus protection of differential traveling-waves with the restraint characteristic, and advances the practicable protection algorithm using the wavelet transform. The theoretical analysis and EMTP simulation tests show that the bus protection operates rapidly, sensitively and reliably, and that its performance can endure the influences of various fault path resistances, fault inception angles, fault locations and fault types.