Non-stop power transfer is the key method to improve the reliability of power supply

but direct loop closing may produce excessive current and affect the safety of operation. Rotary power flow controller (RPFC) can realize zero-sensing loop of substations

but improper voltage regulation trajectory will cause voltage limit violations at the RPFC terminal. To address the issue

this paper proposes a flexible loop-closing method for distribution networks based on a two-stage optimal path using the RPFC. Firstly

the output voltage trajectory is systematically planned and divided into two stages: in the first stage

the voltage phases at both ends of the loop-closing point are aligned

and the voltage amplitudes are constrained to be equal

ensuring a smooth voltage transition. In the second stage

based on phase alignment

the RPFC output voltage is controlled to reach the target value

ensuring equal voltage amplitudes at both ends of the loop-closing point. Next

phase angle difference calculation and rotational angle coordination control are employed to select the nearest rotational angle setpoint as the target value

achieving precise voltage regulation at both ends of the loop-closing point. Finally

simulation and experimental comparative analyses demonstrate that the proposed method reduces voltage limit violations by at least 30%

showcasing the significant application value of the RPFC in achieving flexible loop closing in distribution networks.