Integrating Multiple Reserves in Unit Commitment Problem: A Hybrid Optimization Approach

The increasing penetration of renewable energy introduces significant uncertainties in power systems, necessitating advanced strategies to maintain economic efficiency and frequency stability. This article addresses the multireserve constrained unit commitment (MRCUC) problem by simultaneously allocating spinning reserve and frequency regulation reserve in systems with high renewable energy penetration. First, spinning reserve requirements are accurately determined by an optimization model addressing imbalances caused by renewable energy volatility and load variations. Second, primary and secondary frequency regulation requirements are quantified through detailed frequency-domain simulations utilizing each unit's frequency-to-active-power-output transfer function, thereby overcoming limitations of traditional first-order frequency approximations applicable mostly to synchronous generators. The proposed comprehensive MRCUC model, characterized by partial observability of load uncertainties and high-ordernonconvexity stemming from precise frequency simulations, cannot be efficiently solved using conventional optimization methods. Therefore, a hybrid optimization framework combining RL with convex optimization techniques is developed to address these complexities, ensuring feasible and effective decision-making. Extensive case studies conducted on IEEE 39-bus and 118-bus test systems confirm the efficacy of the proposed method, highlighting enhanced economic performance, accurate reserve allocation, and robust frequency stability.