The reason for a bipolar commutation failure(CF)caused by a 220 kV AC line interphase fault is analyzed,and the results show that 500 kV AC bus voltage of DC converter station suffers from disturbance after AB-phase failure of the 220 kV line.This disturbance is mainly manifested in the drop of fault phase voltage amplitude and the zero-crossing offset of commutation voltages.As a result,the combination of these two factors triggers CF.Furthermore,the commutation failure prevention(CFPREV)control,as the main method used to prevent CF in actual projects,fails to recognize the fault in time in this fault event and does not play a preventive role for the first CF.Additionally,CF is affected by the complex interaction of control response and accidental factors such as fault moment.In this fault event,the normal commutation process is immediately followed by CF and lacks a transition commutation process which can be adjusted for control reference,which is unfavorable.Finally,based on this fault case,some relevant suggestions are proposed for the analysis and mitigation of CF.
high voltage direct current(HVDC)transmissioncommutation failureAC line interphase faultcommutation failure prevention(CFPREV)control
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