Survey of commutation failures in DC transmission systems

The mechanism of commutation failure in DC transmission system is analyzed and the MIIF(Multi-Infeed Interaction Factor) of MIDC(Multi-Infeed Direct Current) transmission system,relevant to commutation failure,is introduced. The system parameters and electric parameters,closely relevant to the extinction angle in the operation of invert system,are analyzed and the main influencing factors of commutation failure in DC transmission system are summarized. The main methods of commutation failure judgment are introduced and three criteria are given for detecting if commutation failure is synchronously occur in different inverter stations of MIDC transmission system:coupling impedance,MIIF and effective short circuit ratio. The suppression measures and system recovery strategies after commutation failure are summarized.