Study of transient-based phase selection for EHV transmission line relaying

New development in relay protection for smart grid

“…Main protection component and the principle employed [1][2][3][4][5][6][7][8][9][10][11][12] (1)Starting Unit(SU): based on the sudden change in the characteristic (Lipschitz coefficient) of the initial traveling wave caused by a fault on the transmission line, it adopts the "wavelet modular change and Wavelet Transform Module Sum" method to detect the signal singularity and to construct the fault start and interference not start element. (2)Direction Unit(DU): when the fault is from the forward direction, the ratio of the positive direction traveling wave to the reverse direction traveling wave is Δuf /Δub = kr, where kr is the reflection coefficient and 0 < |kr| < 1.…”

Fast phase selection method based on transient current for UHV transmission lines

“…The initial travelling wave‐based FPS methods can quickly identify the faulted phases [1, 2], but it is defective in its vulnerability to fault arc, small fault inception angle, the wave reflection and refraction. Thus, the fault‐generated transient‐based FPS schemes have been developed [3, 4], which utilise and extract the fault‐type information during a period of time after a fault occurs. Compared to the initial travelling wave‐based FPS methods, the transient‐based FPS schemes have higher reliability, but slightly slower identification speed.…”

“…Many advanced mathematical tools are applied in FPS schemes to obtain better performance. With the good time–frequency localisation, wavelet transform (WT) has been widely used in fault classification [1, 2, 4, 5]. A novel neural network‐based technique for phase selection is presented in [3].…”