Fault Detection During Asymmetrical Power Swing Using Superimposed Negative Sequence Current

Abstract

Power swing phenomenon occurred during single-pole auto-reclosing (SPAR) period is called asymmetrical power swing. During symmetrical power swing, power swing blocking is used to block distance relay to avoid the selectivity property. Therefore, fault detection is more challenging during asymmetrical power swing since open-pole condition introduces large amount of negative and zero sequence components in voltage and current signals. Further, fault detection during power swing and SPAR prevailed in a series compensated line is more challenging as the metal oxide varistor protecting series capacitor imposes other frequency components. In this paper, a new superimposed negative sequence (NS) current-based technique is proposed to detect the fault incepted in a series compensated line during asymmetrical power swing. The superimposed NS current is calculated using phasor difference between the fault and prefault NS currents. The proposed technique exploits the presence of substantial amount of superimposed NS current during asymmetrical power swing period to detect fault accurately. A summation index is used to declare the fault when it crosses the threshold value. Transient data, obtained from two systems simulated using PSCAD/EMTDC software, are used to test the performance of approach.