Resynchronization scheduling policy for multiple microgrids for optimal distributed system operation with enhanced flexibility

Microgrids are expected to enhance reliability and flexibility by utilizing islanding mode to efficiently manage distributed power sources within the modern distribution power system. After entering the islanding mode, microgrids must be resynchronized with the main grid. However, during the resynchronization process, connecting and islanding multiple microgrids can lead to rapid power ramp-up or ramp-down. In systems with multiple interconnected microgrids, the scheduling of islanding mode and resynchronization becomes a critical management factor. This paper proposes an optimal operation model for power systems, based on a resynchronization policy for multiple microgrids. The proposed policy determines the duration of the islanding mode for each microgrid and adjusts trading volumes with the main grid after resynchronization. Two resynchronization methods are introduced to mitigate flexibility shortages during microgrid resynchronization. The K-value rotation method assigns different islanding durations to microgrids, enabling sequential resynchronization. The Gradual flow limit increment method applies a uniform islanding duration but gradually restores power exchange rather than instantaneously resynchronizing. The effectiveness of the proposed methods is evaluated by comparing operating costs under different resynchronization policies.