The beat frequency characteristics of the recovery voltage of fault phase in the case of single-phase grounding transient fault happening to line with the shunt reactor are analyzed. Besides, the paper analyzes the reason of no beat frequency phenomenon of transient fault happening to line without shunt reactor. The AC power network with metallic grounding fault and arc grounding fault is analyzed by simulation. The recovery voltage of single-phase grounding fault in AC/DC hybrid power grid is studied by PSCAD. The new problems of the adaptive re-closure in AC-DC hybrid power system are discussed. Then the follow-up ideas to solve several existing problems are also presents.

beat frequency; adaptive re-closure; AC/DC hybrid power grid; transient fault; permanent fault