Scheme for transient traveling wave -based directional protection using mathematical morphology

To overcome the shortcoming of misjudgment in the traveling wave-based directional protection,a new scheme is proposed based on the analysis of characteristics of transient traveling wave voltage and current of power system faults occurred in EHV transmission lines.The mathematical morphology is used to extract the transient features of voltage and current.The basic principle of this scheme is demonstrated.The polarities of transient voltage and current are compared.ATP simulation on a typical 500 kV EHV transmission line system is conducted.Simulation results of different fault inception angles and fault resistances prove that this scheme is effective under different fault conditions.