Detection of Power Swing and Fault During Power Swing Using Lissajous Figure.

The paper demonstrates a power swing blocking and unblocking technique for a distance relay in a hybrid transmission line consisting of an overhead line and an underground cable using the Lissajous figure of the voltage and current signals. The tangents perpendicular to the axis of the current signal (denoted as TPI) on the Lissajous figure are found at exactly half cycle spacing during normal condition, while their spacings deviate from half cycle and are unequal during the power swing and a large number of TPIs are found within a small duration after fault initiation. This feature of the Lissajous figure is utilized to detect the power swing and the fault during the power swing. The proposed method is tested on a 5-machine 14-bus power system, simulated in electromagnetic transient program for symmetrical, asymmetrical, and nonideal faults, and found accurate. The faults during the power swing are detected within few milliseconds after fault initiation for different fault locations, fault resistances, load angles, fault inception times, and swing frequencies. The comparative analysis with two conventional and two novel methods shows the potential of the proposed method. [ABSTRACT FROM AUTHOR]