Three-phase fault direction identification method for outgoing transmission line of DFIG-based wind farms

Doubly-fed induction generator (DFIG)-based wind farm has the characteristic of transient fault with low voltage ride through (LVRT) capability. A new three-phase fault direction identification method for the outgoing transmission line of the wind farm is presented. The ability of the new directional relay to differentiate between a three-phase fault in one direction or the other is obtained by using the increment of phase angle difference between the memory voltage signal and the fault current signal within a certain time, and using the amplitude variation of the fault current. It can be inferred that the fault current is supplied by the wind farm whether the phase angle differs or the current amplitude varies considerably. Different fault locations at the outgoing transmission line have been simulated by PSCAD/EMTDC to evaluate the reliability and sensitivity of the proposed technique. Results show that the new directional relay is of faster response when a three-phase fault occurs at the outgoing transmission line of a DFIG-based wind farm.