Identification of Lightning Stroke and Fault in the Transient Component Based Protection

To resolve the impact of transient traveling wave induced by lightning stroke on the transient component based protection of transmission line, a novel identification algorithm is proposed. Using the characteristics of symmetry of waveform induced by lightning stroke without causing fault and asymmetry of waveform generated by fault within a very short interval, the waveforms of transient current above and below time-axes are integrated respectively. First, through comparing the ratio of them with threshold value, the primary criterion identifying fault and lightning stroke is constructed; Secondly, to improve the reliability of discrimination between lightning stroke with and without causing fault, according to the difference of them, the secondary criterion is also defined. The simulation results from EMTDC demonstrate that the proposed integral criterions are valid and correct.