Time Domain Distance Protection of AC Transmission Line Near Inverter Station

The AC line fault near the LCC-HVDC inverter station usually causes commutation failures (CFs). The accuracy of power frequency phasor extraction will be affected by the distortion of fault voltage and current waveform, resulting in deterioration of power frequency phasor distance protection performance. The adaptability of the traditional power frequency phasor distance protection is analyzed by simulation. Then, according to the AC line RL model, a time domain distance element based on the polarity comparison of the instantaneous voltage at the protection installation and the instantaneous voltage of the setting point compensation is proposed. The proposed time domain distance element is not affected by the nonlinear output characteristics of the inverter station. Finally, the effectiveness of the time domain distance protection is verified by simulation.