Hierarchical Load Restoration for Integrated Transmission and Distribution Systems With Multi-Microgrids

This paper proposes a novel integrated restoration method for transmission (TS) and active distribution systems (DS). The proposed method capitalizes on multi-microgrids' (MMGs') enhanced controllability across multiple levels of the modern bulk power system (BPS) to develop a new constraint hierarchy approach, formulating the restoration problem as three mixed-integer linear programming (MILP) subproblems. Based on the constraint hierarchy approach, the coordinated load restoration process is able to overcome the multiple regulations and jurisdictions limitations imposed on sharing resources between DS- and TS-level, while significantly reducing computational burden compared to non-linear methods. This critical feature not addressed in the literature can lead to unfeasible solutions and meaningfully compromise the restoration performance. Moreover, the developed method can unlock and coordinate the previously inaccessible resource transactions between different BPS levels, i.e., local-local (DS) and global-local (TS) levels. Therefore, significantly improving load pick-up capacity, service capability, and restoration time at both DS- and TS-level. Finally, comparative case studies with state-of-the-art and benchmark strategies are used to validate the proposed method. The obtained results showcase the effectiveness and advantages of the proposed method in enhancing the coordination of integrated TS- and active DS-restoration process.