Research on Flexible Mutual Aid Control Strategy of Interconnected Transformer Area Based on Distributed Power Flow Controller

To address the issues of uneven transformer loading and underutilized capacity in conventional distribution areas interconnected by bus-tie switches, this paper proposes a flexible mutual-aid control strategy based on the distributed power flow controller (DPFC). An equivalent model of the interconnected transformer area system is established, and the phasor relationships between the DPFC’s injected voltage amplitude, phase angle and transmitted power are analytically derived. On this basis, a capacity-ratio-oriented mutual-aid control strategy is developed, enabling the DPFC to dynamically distribute active power according to the rated capacities of interconnected transformers. A simulation model is built in PSCAD/EMTDC to validate the proposed method. The results demonstrate that the strategy achieves full power mutual aid among transformer areas, reducing the heavy-load transformer utilization from 76.67% to 30.56%, thereby realizing rational capacity allocation and improving the operational reliability and efficiency of the distribution network.