A new differential current circle diagram based technique for long transmission line protection

In view of sensitivity, selectivity, and operating speed of the relay, the current differential technique is an alternative against overcurrent and distance-based techniques for long transmission line protection. Moreover, this technique has limited performance due to Line Charging Capacitive Current (LCCC), Current Transformer (CT) saturation further, by using synchronized data, the effect of LCCC can be nullified. However, in case of synchronition is lost, the performance of the current differential is not reliable. Hence, in this paper, the Inverse of Difference of both end Current phasors (IDC) is applied to prevent maloperation due to channel delay and synchronization loss. The simulation experiments are conducted under various operating conditions on a 345 kV, 50 Hz, IEEE 39-bus network using PSCAD 4.5 and MATLAB (R2020a). Results reveal the enhanced security under CT saturation, LCCC and sensitivity under high resistance line to ground faults.