Characteristics of AC bus voltage in converter station when commutation failure

Commutation failure is common in HVDC transmission system. The fault recording in one converter station when commutation failure caused by disturbance of AC system was collected in this paper, and the landing amplitude, zero crossing offset and commutation area of the AC bus voltage was calculated and statistical analyzed. The results suggested that, when commutation failure: 1) The average landing amplitude of effective value of the AC bus phase voltage and line voltage was 5.13% and 4.6%, and the peak of zero sequence voltage was basically less than 50kV; 2)The average of zero crossing offset of the AC bus line voltage was −4.24 degree. But there were few cases that the zero crossing was lagging, but commutation failure occurs. 3) The average reduction of the commutation area was 22.02%, and the reduction was less than 30% in most cases. The results will provides basic data for analyzing the main influencing factors of commutation failure and setting up countermeasures for HVDC system.