A Hierarchical Dispatch Model for Wind–Solar–Thermal Storage Systems Considering Optimal Curtailment Rate to Enhance Economic Integration

This paper proposes a bi-level optimal dispatch model for a wind–solar–thermal-storage hybrid power system that considers the optimal curtailment rate. The upper-level model minimizes net-load fluctuations and curtailment penalties by coordinating renewable curtailment and energy storage scheduling under multiple uncertainty scenarios. The lower-level model minimizes the total operating cost by optimizing thermal unit commitment and dispatch while accounting for deep peak-regulation costs, spinning reserve costs, environmental taxes, and the environmental benefits of renewables. A piecewise nonlinear cost model is introduced to characterize the increasing wear-and-tear and oil-support costs of thermal units operating under deep peak regulation. Simulation results obtained on a modified IEEE 30-bus system demonstrate that, compared with benchmark models, the proposed approach significantly smooths the net-load curve, reduces the peak-to-valley difference, and lowers the total system operating cost. The results further indicate that moderate active curtailment, when coordinated with energy storage, can be more economical than rigid full renewable accommodation. Consequently, active curtailment should be regarded not merely as a loss of renewable energy utilization but as a flexible and economically rational resource for enhancing system security, flexibility, and overall dispatch performance.