Three-Phase Fault Detection During Power Swing by Transient Monitor

Distance relays are immune to inadvertent operation during power swings by a block known as “power swing blocking (PSB)”. Its main function is discriminating faults from power swings. However, if a fault occurs during a power swing, PSB should be de-blocked and let the distance relay to operate normally and clear the fault accordingly. Meanwhile, discrimination of a three-phase fault from a power swing is the most difficult task due to their likelihood. This paper proposes a new method to overcome this issue by monitoring the transient period established in the process of current dynamic phasor estimation. In this regard, transient monitor (TM) index, which is the difference between the estimated current samples regenerated from the calculated dynamic phasors and the actual sample values, is used to distinguish the fault from the power swing. Fourier-Taylor transformation is applied to estimate the dynamic phasor of the current signal. Simulation results verify the inherent potential of the proposed method to overcome the issue.