In this paper, a supervisory PMU-based protection scheme is proposed to prevent mis-operation of conventional protection systems against stress conditions at the transmission level. According to the proposed method, a vulnerable area in power systems is identified using the buses, equipped PMU, with the highest distortion in voltage magnitude following an event. For a suitable implementation of the PMU-based proposed scheme, an analytical strategy is employed to optimize the installed PMUs number in the power system regarding the protection approach. Then, equivalent admittances between every two PMU-buses, surrounding the specified area, are calculated and analyzed as the key indices for fault detection. The equivalent admittance, emulating the transmission line behavior, is a function of the voltage and current of the monitored buses, and hence could be used to accurately detect the occurrence of a fault. Besides, a load-flow-based scheme is proposed for accurate fault distinction from load-increasing events. Afterwards, the impact of measurement errors on the proposed method performance is analyzed using the sensitivity analysis approach. Verification of the proposed method has been evaluated on a two-area power system and a IEEE 73-bus benchmark in the Simulink/MATLAB environment.
