In order to improve the reliability of the traditional transient protection

a novel protection method of transmission line based on the fault information of broadband transient signals both in time domain and frequency-domain is proposed. In the proposed protection method S-transform is utilized to extract fault information of broadband transient signals in frequency bands and time periods

and time-frequency variation characteristics of transient signals is reflected by constructing the time-frequency matrix. Characteristics of time-frequency matrix is extracted by singular value decomposition

and matrix redundancy can be reduced. Characteristic difference between singular value matrix and database matrixes is searched by time-frequency matching algorithm and matrix similarity is calculated. Finally

the matrix similarity is obtained to distinguish the internal and external fault. The simulation results show that the fault inside the protection zone can be rapidly and accurately distinguished from the fault outside the protection zone by the proposed protection method.