Using incremental replica current in phase comparison transmission line protection schemes: Advantages and limitations

In this paper, the use of incremental replica currents in time-domain phase comparison line protection schemes is evaluated, highlighting its advantages and limitations. The incremental replica current has been applied in modern highspeed numerical protection relays, showing to be suitable for protection functions based on time-domain analysis. In order to carry out the proposed studies, the Alternative Transients Program (ATP) was used to simulate a wide variety of fault scenarios in a 500 kV/60 Hz test power system, considering different fault features (distance, resistance and inception angle), Source-to-Line Impedance Ratio (SIR) values and system loading conditions. In each case, the tripping times of the time-domain phase comparison protection when implemented using traditional phase currents and incremental replica currents are compared. The obtained results show that the use of incremental replica currents improves the phase comparison protection reliability, speeding up the protection operation times in cases of adverse DC decaying components.