Spectral Energy Differential Approach for Transmission Line Protection

A new transmission line differential relaying scheme is presented in this paper. The proposed scheme is based on the comparison of the transient energy in the current signals at both ends of the transmission line. Discrete wavelet transform (DWT) has been employed to extract the transient energy in the current signals. A sliding data window with a length equivalent to half cycle of the fundamental power frequency is used to achieve high speed relaying. The proposed scheme has been extensively tested using computer simulations and in real-time using a DSP board. The scheme presented in this paper, provides sensitive protection for transmission line faults, and high security and stability for external faults. The obtained results show the feasibility of the proposed relaying scheme