Abstract: To address the challenges of power supply assurance in high-altitude border terminal grids, including weak grid structures, severe source-load fluctuations, a high risk of system-wide outages following faults, and the inability of a single control system to meet the regulation requirements throughout the entire operating process, this paper establishes a full-time-scale control architecture based on an actual engineering project in Dingjie County, Tibet. The architecture enables coordinated operation of grid-forming energy storage, a security and stability control system, and a coordinated control system, and achieves closed-loop regulation of the microgrid over time-scales ranging from milliseconds to minutes. Experimental results demonstrate that the proposed architecture coordinates fault emergency response and steady-state power balance, ensures continuous power supply to core loads across the county for more than 4 h, and provides an engineering reference for the coordinated regulation of high-altitude power supply assurance microgrids and for improving the level of power supply assurance.