An integrated scheme for a directional relay in the presence of a series-compensated line

This paper presents an integrated method to identify the fault direction in the presence of a series compensator via also identifying the power flow direction. The presented method relies on monitoring both measured angle of the positive-sequence (PS) currents and magnitude of PS voltage. The change of PS voltage magnitude is used to detect the current inversion case. The presented criteria depend on the power flow direction before the fault occurrence. Therefore, a power flow direction identification method is presented using only the change of the phase angle of the PS current. Different system configurations are investigated to test the reliability of the proposed protection scheme (PPS). The power and protection systems' configurations contain different capacitor ratios leading to current and voltage inversion scenarios, reversing the power flow direction and single-pole tripping. Simulation experiments conducted via the software ATP-EMTP has shown the proper operability of the PPS.