A Novel Power Swing Detection Scheme Independent of the Rate of Change of Power System Parameters

During power swings, the distance protection may experience maloperation. Most recently, practical distance protection has used the rate of change of power system parameters. For example, the speed of the impedance trajectory movement through the blinder characteristics is generally used to distinguish between the fault and power swing. These methods experience maloperation in the external faults or in stable power swings. The proposed method solves the shortcomings via an approach that does not use the rate of change of power system parameters. In this paper, the circular locus of the admittance trajectory and its center behavior are investigated to detect power swing conditions based on a relay flowchart. The proposed method is able to detect power swings reliably before the impedance trajectory enters the distance protection zone. In addition, symmetrical and asymmetrical faults during power swings can be detected quickly to prevent power system instability in critical conditions. Simulation results show that the proposed method provided superior performance in comparison with other methods, especially for maloperation. In addition, unlike most power swing detection schemes, the proposed method is not affected by the selected power swing frequencies even for high-frequency swings (10 Hz).