The DC line fault recovery function is of great importance to ultra-high voltage direct current (UHVDC) projects in enhancing operational reliability. First

the impact of UHVDC recovery for the line fault on the security and stability of AC system is analyzed and described in detail by taking UHVDC projects in operation presently as examples. Secondly

both the time sequence of UHVDC bipolar cascading line fault and the system stability characteristics are analyzed

and a three-stage cascading fault recovery strategy is proposed based on the analysis results. The proposed strategy will provide a theoretical guidance for all DC projects to draw up their cascading fault recovery schemes. In the end

an UHVDC project in Southwestern China is taken as an example to verify the efficiency of the proposed strategy.