An algorithm for distance protection based on the change of the voltage phase angle

Conventional distance protection methods usually require additional filtering of the input signals to remove the influence of the DC component and the distortion of sinusoidal signals. The paper shows an algorithm that does not require additional filtering of the input signals. The proposed algorithm uses measured voltages at the beginning of the line and auxiliary voltages as input signals. The auxiliary voltages were calculated from measured currents and voltages at the beginning of the line and known line parameters. The algorithm compares the instantaneous values of the measured and calculated auxiliary voltages and detects a fault on the line based on the change in the phase angle of the voltage. Testing of the presented algorithm was performed with signals obtained from computer simulations of line faults and recordings of faults from protection devices from the real network. The obtained results confirmed that the algorithm represents fast and sensitive protection of transmission lines.