A novel wavelet approach to busbar protection during CT saturation and ratio-mismatch

Abstract

This paper deals with the use of a continuous wavelet transform (CWT) to distinguish faults in a busbar protection zone from those outside the zone. The Morlet wavelets are used as the wavelet basis function. They are more efficient in monitoring fault signals as time varies. The differential current as the operating quantity and the sum of the current magnitudes as the stabilizing signal are computed. The magnitudes of the CWT of these currents are derived to obtain the operational and restraint signals. The CWT coefficient plots are given to precisely determine the scale of analysis. The proposed wavelet transform approach based on Morlet basis function is found to be an excellent discriminant for identifying the fault signals during the CT saturation and ratio mismatch. ATP simulations are used to test and validate the proposed CWT approach for model power system faults.