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

The paper studies a novel bus protection based on transient current traveling-waves for avoiding the adverse effect of current transform (CT) transient saturation. First. 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, a restraint traveling-wave is introduced into the DTW. Thus the paper proposes the bus protection of differential traveling-waves with a restraint characteristic, and advances a practical protection algorithm using the wavelet transform. 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.