Two-Stage Robust Optimization for Resilient Operation of Microgrids Considering Hierarchical Frequency Control Structure

Following a major outage in the main grid due to natural disasters, microgrids (MGs) have the ability to disconnect from the main grid and provide electricity to their consumers. However, integration of power electronic-based generation units and small-scale energy resources into MGs reduces the system inertia. Therefore, frequency deviations arising from the loss of grid power or fluctuations of renewable energy resources and loads should be managed. In this article, a two-stage robust day-ahead optimization model for resilient operation of MGs is proposed in which the hierarchical frequency control structure of the MG is precisely formulated. Based on this model, the operation cost of MG is minimized while sufficient primary and secondary reserves are scheduled to restrict frequency deviations and avoid load shedding under the worst-case realization of islanding events. A column-and-constraint generation algorithm is utilized to efficiently solve the problem. Numerical cases on a test system show the effectiveness of the proposed model and the solution algorithm. The obtained results verify that by applying the proposed model, the operating cost of MG is minimized while the frequency deviation and load shedding can be successfully managed during islanding events.