Transformer Inrush Current Impact on Commutation Failure Prevention of UHVDC Transmission system

This paper studied the influence of transformer inrush current on commutation failure prevention control of Ultra-high voltage DC (UHVDC) transmission system. An actual event occurred on Tianzhong UHVDC transmission project was analyzed with data from fault recorder. UHVDC transmission model with commutation failure prevention control was established in PSCAD/EMTDC, and then it was applied to replay the event. It is found that the frequent maloperation of commutation failure control and the fluctuation of DC power exist when inrush current occurred. An improved commutation failure prevention control strategy was proposed to avoid this phenomenon. Validity of the improved method was proved by the simulation results.