Nowadays, the increasing demand for power has challenged the line design capacity overwhelmingly, which has become a severe problem in micro-grids. The dynamic increase in line capacity is an effective solution to this problem. It determines the actual capacity of the line by actual meteorological conditions and real-time monitored line parameters. First, this paper analyzes the influence of the real-time status of various devices on line capacity based on the topology of micro-grid and then demonstrated the feasibility of dynamic capacity increase. Based on the general dynamic capability model, this paper proposes a dynamic capability model based on big data situational awareness technology, which provides the operational basis for dynamic capability improvement. The effect of different factors on dynamic capacity estimated by simulation, from which conclusions are derived. The effect of the model with situation-aware this paper proposes aligns well with the general model. Finally, this paper presents key concepts relevant to real-time situation-aware technology with a graphical interface. The research results lay a foundation for the dynamic growth of micro-grid in actual operation, and have certain reference value for the stable and safe operation of offshore oil platform grid, and will be popularized in the future work.