Optimal Fault Recovery in Distribution Networks with Multi-State SOP Regulation and Network Reconfiguration

[Objective] Following fault-induced outages in flexible interconnected distribution networks，devices such as Soft Open Points （SOPs） can enable rapid and coordinated power rerouting or support islanded operation. However，existing studies overlook the impact of different control states of flexible devices on restoration performance. Moreover，conventional predefined islanding schemes have limited capability in determining the effective support radius and restoration priority enabled by SOP. To address issues related to the feasible control strategies of interconnected devices，this paper proposes a fault restoration strategy based on the equivalent model of the SOP. [Methods] An alternating iterative power flow algorithm is developed to incorporate SOP with multiple control modes and to compute the post-restoration power and voltage distribution. By jointly optimizing SOP control mode selection and non-predefined network reconfiguration，a restoration model is established with the objective of minimizing weighted operational losses，while fully considering power flow constraints and multi-terminal SOP control limitations. To efficiently solve the resulting large-scale optimization problem，a genetic algorithm enhanced with a cooperative graph Laplacian operator is employed for efficient solution. Post-fault restoration performance was evaluated on an interconnected dual IEEE 33-bus test system. [Results] The results demonstrate that，in response to different topological changes and distributed generation outputs after line outages，the proposed method can dynamically generate appropriate non-predefined reconfiguration schemes. It also enables coordinated adjustment of SOP control strategies at different locations. Compared to conventional reconfiguration approaches，the proposed strategy improves the load restoration ratio by 14%. [Conclusions] The non-predefined network reconfiguration contributes to a higher post-fault load restoration ratio. When combined with optimized SOP control states，it yields a more favorable post-restoration voltage profile and supports high supply resilience in flexible interconnected distribution networks.