A new power-based digital algorithm for generator protection

In this letter a new power-based digital algorithm is introduced to provide protection for the generators against unbalanced faults. The algorithm measures the generator's three-phase power output and monitors the sinusoidal component of the instantaneous power. When the magnitude of the sinusoidal component exceeds a predefined value, the algorithm checks the direction of the negative sequence-reactive power flow to discriminate between internal and external faults. The proposed algorithm initiates fast tripping for internal asymmetrical faults, and provides back up protection for external unbalanced conditions.