Secure backup protection of transmission line using WAMS

Segregated phase comparison technique, a special form of current differential protection is widely applied for the protection of transmission line due its simplicity. It takes into account the difference of phase angle of currents at two terminals of transmission line. In this paper, one Relay/PMU is placed at sending end and to calculate receiving end voltage and currents; data is used from neighbor Relay/PMU to protect long power transmission line based on synchrophasors in SMART grid. This scheme considers segregated phase comparison after compensation of line charging currents. These phase currents are compared at control center for line under consideration to detect the fault condition. An equivalent π-model of transmission line is considered for analysis and global positioning system is used for synchronised measurements. The phase differential function is developed using phase coordinates. IEEE 14 bus system is simulated in ATP/EMTP environment. The relay is assessed as a backup relay based on the communication speed for data transferring. The protection scheme is analyzed using MATLAB program which demonstrates the accuracy of the proposed scheme.