Blackouts are disastrous events with a low probability of occurrence but a high impact on the system and its users. With the help of more distributed and controllable generation and sector-coupled flexibility, microgrids could be prepared to operate in islanded mode during a blackout. This paper discusses a two-step blackout mitigation approach for highly renewable microgrids that utilizes user flexibility and energy storage systems for power balance in islanded grid operation. The proposed method includes a proactive flexibility reservation step, which derives a minimal reservation schedule for microgrid resources under uncertainty considering related operational costs. As a second step, during a blackout, a fully distributed control is implemented to maximize the usage of available resources based on a sequence of max and min-consensus rounds. This paper focuses on the second step, for which the effectiveness of blackstart and long-term coordination is shown. Load shedding can be reduced by 40\% compared to the forecast value. A hardware-in-the-loop simulation of a grid-forming converter further showed a fast convergence toward the optimal operation point.
