Statistical discrimination index founded on rate of change of phase angle for immunization of transformer differential protection against inrush current

Magnetizing inrush currents are known as the most critical potential threat in maloperation of transformer differential protection. Therefore, there is a need to detect current from internal fault avoid protection maloperation. Due possibility (CT) saturation at high level and current, discrimination algorithm should function appropriately CT conditions. Here, method developed based on rate phase angle change (RoCoPA) perform process. The proposed index employs RoCoPA three-phase calculates standard deviations currents. procedure designed fact that during scenarios, signal remains almost sinusoidal, result, has minimum variations. On contrary, owing non-sinusoidal wave shape notable Based various simulated practical index's performance evaluated considering challenging scenarios. results reveal promising accuracy with average response delay about half cycle.