Load transfer without power interruption in the loop closing of an active distribution network is the core technology for improving the reliability of power supply. A single rotary phase shifting transformer (RPST) is used in the loop closing scenario with a 30° phase angle difference. However, its regulation mode is single and cannot realize flexible loop closing under any voltage deviation. In this study, a dual rotary phase shifting transformer (DRPST) is proposed to achieve the function of continuously regulating voltage amplitude and phase angle at the loop closing point through the cooperation of dual rotor angles. This DRPST exhibits the advantages of a flexible control mode, high control precision, and high reliability. First, the working principle and mathematical model of the proposed DRPST are analyzed in accordance with its topology. Second, the voltage phase difference feedback method at both sides of the loop closing point based on virtual power is adopted, and the reference value of the DRPST synthesis vector of voltage is obtained by combining with voltage phase and amplitude deviations. Then, the reference value is converted and decomposed into the reference values for dual rotary phase shifting angles, realizing the non‐differential regulation of voltage at both sides of the loop closing point through the closed loop control of double rotor angles and the coordinated control of the servo motors’ speed. Finally, a DRPST device with a capacity of 40 kVA is developed and a loop closing experiment is performed, verifying the feasibility and effectiveness of the proposed DRPST in realizing the loop closing of an active distribution network.

With the rapid development of active distribution networks, the “petal”-type distribution network has become the mainstream power supply structure. To ensure the safe and reliable power supply of a distribution system, power control methods for active distribution networks should be further studied. An electromagnetic rotary power flow controller (RPFC) is a feasible solution for active distribution network power control. However, when testing the effectiveness of the PQ decoupled control method for RPFC based on instantaneous reactive power theory, difficulties were encountered with the synchronous control of the rotor position angle of two rotating-phase transformers, and the accuracy of power control was unsatisfactory. Given this condition, PQ control is improved in three ways. First, the system periodic oscillation problem is solved via variable speed control. Second, the servo motor–rotary phase-shifting transformer synchronous rotation scheme is designed, reducing power control error and improving stability. The overshoot phenomenon in power control is improved using the variable domain fuzzy proportional–integral adaptive method. Experimental results show that the proposed advanced control scheme exhibits good dynamic and static performance in power control scenarios and achieves effective improvement of RPFC.

With the rapid development of active distribution networks, the “petal”‐type distribution network has become the mainstream power supply structure. Power control methods for active distribution networks should be further studied to ensure the safe and reliable power supply of a distribution system. An electromagnetic rotary power flow controller (RPFC) is a feasible solution for controlling power in active distribution networks. However, when testing the effectiveness of the PQ decoupled control method for RPFC based on instantaneous reactive power theory, difficulties were encountered with the synchronous control of the rotor position angle of two rotating‐phase transformers, and the accuracy of power control was unsatisfactory. Given this condition, PQ control is improved in three ways. First, the system's periodic oscillation problem is solved via variable speed control. Second, the servo motor‐rotary phase‐shifting transformer synchronous rotation scheme, which reduces power control error and improves stability, is designed. Third, the overshoot phenomenon in power control is improved using the variable‐domain fuzzy proportional‐integral adaptive method. Experimental results show that the proposed advanced control scheme exhibits good dynamic and static performance in power control scenarios and achieves effective improvement in RPFC.

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