To improve the feasibility of inter-provincial electricity spot market and ensure secure and stable operation of large-scale interconnected power grids

this paper proposes a market clearing model incorporating complex operational constraints across provincial power systems. First

the secure operation mechanisms of interconnected grids are analyzed to systematically identify critical constraints in the inter-provincial spot market. An iterative clearing framework is then developed

integrating centralized optimization with dynamic constraint relaxation

which enhances market clearing efficiency while complying with existing trading protocols. A unified optimization model is further established to explicitly embed operational coupling constraints between generation and transmission facilities within the market clearing process. Case studies validate that the proposed model effectively captures operational coupling constraints of key AC/DC transmission facilities

generates transaction plans compliant with cross-regional grid security requirements

and improves both the practicality of market outcomes and resource allocation efficiency in the inter-provincial electricity spot market.