Frequency Constrained Proactive Scheduling for Secure Microgrid Formation in Wind Power Penetrated Distribution Systems

Microgrid formation (MF) is a core solution for increasing the resilience of distribution systems in extreme situations. However, a significant power imbalance at the MF onset will result in the violation of dynamic frequency constraints, especially in low-inertia wind power penetrated distribution systems (WPP-DSs). To ensure the secure MF after emergencies, this paper proposes a frequency constrained proactive scheduling method for WPP-DSs. The primary frequency response (PFR) model is proposed to describe the microgrid frequency dynamics after islanding, where wind turbines are deloaded to provide a primary reserve. Then the PFR model is incorporated into the scheduling model to ensure frequency security during MF process. The proposed method proactively dispatches controllable units to mitigate the power imbalance and to reserve power for frequency regulation. After emergencies, the primary reserve is released, and adaptive microgrids are securely formed to sustain critical services. The PFR model is formulated as algebraic differential equations (ADEs), which makes it difficult to solve the model directly. Thus, the PFR model is discretized into difference equations and further linearized to facilitate solution. Simulation results validate the merits of the proposed method in reducing the conservatism of proactive scheduling strategies and improving the microgrid security during MF process.