Multi-Region Thermal-Renewable Coordinated Dispatch Considering Chance-Constrained Reserve and Supply Security

In multi-region power systems, renewable energy fluctuations and uneven resource distribution pose challenges to system security, especially under sharp renewable output drops. To address this issue, this paper proposes a tie-line reserve sharing constraint, where the reserve provided to other regions originates from local thermal generation capacity and is restricted by tie-line transmission capability, accurately representing the mechanism of cross-regional reserve coordination. Furthermore, a chance-constrained reserve formulation is introduced to ensure the reliability of 95% supply while avoiding the excessive conservatism of traditional robust optimization. On this basis, a multi-region day-ahead scheduling model integrating unit commitment, reserve sharing, and tie-line constraints is developed to achieve an optimal trade-off between economy and reliability. Case studies in a provincial power system in China demonstrate that the proposed model significantly improves renewable energy utilization, enhances operational flexibility, and ensures secure supply under extreme conditions, verifying its practical effectiveness for coordinated multi-regional scheduling and supply security applications.