Power systems with high-penetrated renewables are facing severe challenges of guaranteeing power supply and promoting the consumption of renewables. Relying on the regional operating reserve market to achieve the inter-provincial aid of reserve resources is an effective way to handle the above challenges. The capacity of transmission lines restricts the delivery of generation capacity reserved by resources. However

the existing methods cannot consider the impact of the delivered reserve on line flows effectively. Moreover

the flexible capacity of transmission lines is not considered in the existing methods. The requirements of capacity reserve and delivery under extreme scenarios cannot be dealt with effectively. To solve the above problems

an intra- and inter-provincial deliverable operating reserve dispatch method considering the flexible capacity of transmission lines is proposed in this paper. Firstly

a unified operating reserve dispatch model of the regional power grid considering reserve delivery scenarios is established. The related reserve delivery constraints for generators under scenarios of power fluctuations of load and renewables are constructed. The deliverability of operating reserve can be improved. Secondly

the line flow constraints considering flexible capacity are further constructed

achieving full utilization of the capacity of transmission lines. Then

regarding the large-scale integer variables introduced by the modeling of flexible capacity

a lossless accelerated calculation method guided by the adjoint model is proposed. Finally

a regional power grid with interconnection among 3 provinces is constructed based on practical data. Case studies validate the effectiveness of the proposed intra- and inter-provincial operating reserve dispatch method.