Study of identification of shielding failure and back striking in UHVAC transmission lines

The identification of shielding failure and back striking in transmission lines is always difficult. The process of back striking and shielding failure in UHVAC transmission lines was analyzed in this paper. Because the mechanisms of produced transient zero module current and its propagation paths were different between back striking and shielding failure, their wavelet energy of different frequency bands of transient currents were different. Thereby, from the perspective of protective relaying, this paper proposes an identification method to shielding failure and back striking in transmission lines based on wavelet transform. All data can be acquired from high speed relay protection device. And the results of PSCAD/EMTDC simulation show the effectiveness of the proposed method.