Design and demonstration of a power flow balancing method for ring-type distribution networks based on rotary power flow controller

• A ring-type distribution network model incorporating the RPFC was established. • An index system based on feeder loading rate and system loading rate was established. • A ring-network power balancing method for the RPFC was proposed. • A 380 V/150 kVA RPFC demonstration project is first reported. • The proposed method was applied to a RPFC operating in the distribution network. To address issues such as local overloading of distribution feeders and reduced system reliability caused by heterogeneous network planning and unbalanced source–load allocation, this paper proposes a power-balancing method for flexible interconnection based on a Rotary Power Flow Controller (RPFC). First, a steady-state model of a ring-type distribution network incorporating the RPFC is established, followed by an analysis of the RPFC-based power-balancing mechanism. The relationship between the power flow in the ring network and the magnitude/phase variations of the RPFC voltage vector is explicitly characterized. A coordinated RPFC regulation framework is then formulated by considering both feeder loading levels and system load-balancing indices, providing the theoretical basis for RPFC-enabled power-flow control. On this basis, a power-decoupling control strategy driven by coordinated dual servo motors of the RPFC is proposed. The effectiveness of the proposed method was validated on both simulation and experimental platforms. Finally, a demonstration project of a 380 V/150 kVA RPFC was established at a test site in Shanxi Province, China, and experimental verification was carried out. The results show that the method can achieve dynamic power-flow allocation according to feeder characteristics. Under experimental conditions, the loading rate of heavily loaded feeders was reduced by more than 38% compared with the scenario without RPFC integration.