Identification of back flash and shielding failure on transmission line based on time domain characteristics of traveling wave

Identification of lightning type can provide directive guidance for the operation and maintenance of transmission lines. In this study, a corresponding relationship satisfied by the polarities of three phases of fault traveling wave current is built under the condition that a fault of transmission line is caused by lightning. On the basis of the lightning overvoltage theory and the boundary condition of transmission line, it is proposed that the back flash should be identified according to the differences and similarities in polarities of three phases of current traveling waves. Based on the modified energy ratio, a method is proposed for the judgment of the transmission line fault caused by lightning and shielding failure, in accordance with the energy variation feature of transient traveling wave. Finally, the identification of types of lightning on the transmission line is achieved. The method is proved to be correct and have good application value by performing simulations and field experiments.