A Novel Approach to Detect Faults Occurring During Power Swings by Abrupt Change of Impedance Trajectory

The main purpose of power swing blocking is to distinguish faults from power swings.
However, faults occurred during a power swing should still be detected and cleared
promptly. This paper proposes an index based on detecting abrupt jump of impedance
trajectory by utilization of predicting capability of Kalman Filter. The proposed in-
dex is calculated by assessing the dierence between predicted and actual samples of
impedance. The predicted impedance samples are obtained using Kalman lter and
Taylor expansion, which is used in this paper to track the phasor precisely. Second or-
der of Taylor expansion is used to decrease corrugation eect of impedance estimation
and increase the reliability of proposed method. The instantaneous estimation and pre-
diction capability of Kalman lter are two reasons for proposing utilizing Kalman lter.
Intensive studies have been performed and the merit of the method is demonstrated by
test simulations.
Keywords: Kalman Filter, Power Swing, Dynamic Phasor, Symmetrical Fault.