Frequency-Constrained Coordinated Scheduling for Asynchronous AC Systems Under Uncertainty via Distributional Robustness

The increasing penetration of renewable energy integration in asynchronous AC systems is gradually lowering the system inertia. Concurrently, the asynchronous interconnection with high-voltage direct current (HVDC) links will limit the frequency regulation resources sharing between sending- and receiving-end grids. These issues put the frequency security of asynchronous AC systems at risk. In this context, we propose a coordinated scheduling model for the asynchronous AC systems that co-optimizes frequency regulation resources from generators, wind farms, HVDC fast-act corrections, and non-critical load shedding, and energy storage systems while guaranteeing frequency security following a contingency. The proposed model explicitly accounts for frequency constraints and manages wind power uncertainty by designing distributionally robust joint chance constraints under the Wasserstein-metric ambiguity set. We show the proposed model admits an optimization model with bi-convex constraints and then develop a sequential solution algorithm to solve it. Case studies demonstrate the effectiveness of the proposed method.