Frequency constrained scheduling for optimal reserve sharing of multi-area asynchronous grids

The integration of wind power and the interconnection of asynchronous grid partitions offer significant advantages, yet they also raise critical concerns regarding frequency security. This paper proposes a multi-area asynchronous grids frequency constrained scheduling (MAG-FCS) method that optimizes day-ahead unit commitment, generation dispatch, primary frequency response (PFR) reserves, regulation reserves, shared reserves, and HVDC power transmission. To enforce the frequency nadir constraint in a computationally efficient and convex manner, a hybrid piecewise affine (HyPA) algorithm is developed. In addition, the proposed method incorporates a Wasserstein-based ambiguity set to model wind power uncertainty and applies distributionally robust (DR) chance constraints to handle constraints involving random variables. Unlike traditional approaches that assume fixed deloading levels, the wind power deloading coefficient is optimized, and the resulting deloaded power is precisely allocated among PFR reserves, shared reserves, and curtailment, thereby enhancing system flexibility. The effectiveness and scalability of the proposed approach are validated on two test systems of different scales. Results show that the method maintains the frequency in all areas of the MAG above 49.5 Hz after a disturbance, with only a 2.22% and 1.32% increase in total cost, respectively. Moreover, enhanced reserve sharing leads to improved economic performance and greater operational flexibility. © 2017 Elsevier Inc. All rights reserved.