Effect of a SFCL on Commutation Failure in a HVDC System

This paper describes an analysis of the effects of a superconducting fault current limiter (SFCL) on commutation failure in a high-voltage direct current (HVDC) system. Most commutation failures are caused by voltage disturbances at the inverter side and cannot be avoided in HVDC systems using thyristors. When ac voltage is recovered to a normal condition, the commutation failure can be removed. However, persistence of the commutation failure can lead to suspension of the converter station. The commutation process is affected by the margin of the extinction angle, commutating reactance, and fault current level. The SFCL can limit the fault current on the ac side of the converter and thus quickly restore the HVDC system to normal status. A detailed simulation based on modeling of an actual system is carried out to verify that the SFCL can reduce commutation failure in a HVDC system.