An Optimized Control Strategy for Mitigating Three-Phase Imbalance and Dynamic Economic Operation in Flexible Interconnected Distribution Stations

With the increasing integration of spatiotemporally unbalanced distributed generations (DGs) and stochastic loads, issues such as three-phase imbalance, low voltage, and transform-er underloading/overloading in low-voltage distribution stations have become more prominent. However, most existing studies address these issues separately, and comprehensive approaches for such multidimensional challenges are rarely implemented. To this end, an optimized control strategy based on three-phase four-wire AC/DC converters is proposed in this article to mitigate three-phase imbalance and achieve dynamic economic operation in flexible interconnected distribution stations. First, the system structure is described, and a split-phase control strategy is proposed for the AC/DC converters to enable independent phase control. Second, an unbalanced power sensing strategy is proposed to estimate the active and reactive power required for each station to restore normal operation without additional devices. Then, a two-layer optimized control strategy is developed to coordinate power dispatch commands for each converter, addressing three-phase imbalance, low voltage, and transformer loading issues. Furthermore, a rapid voltage support strategy is proposed to maintain PCC phase voltages within permissible limits during asymmetrical grid faults. Finally, the effectiveness of the proposed strategy is validated by experiments.