The regulatory capacity sufficiency of the grid is not only a technical indicator for dispatchers to measure the safe and stable operation of the grid, but also an important indicator for assessing the reliability of the grid, and an important basis for the planning and transformation of the grid. This paper combines the objective function and constraints of time and space scale optimal scheduling of provincial power grids with a high proportion of new energy, and establishes a model for optimal scheduling of power grids. Improved DE-ICA stochastic optimization search algorithm is used to seek the optimal value of the model, to obtain the optimal regulation method of the power grid driven by the multilevel spatio-temporal combinatorial optimization algorithm, and to put forward the quantitative assessment method of the adequacy of the power grid regulation capacity. Simulations and empirical case studies show that the regulation cost of the provincial grid is reduced after the application of the optimization algorithm, and the power balance effect and the regulation capacity adequacy are improved compared with the traditional scheme. The quantitative evaluation method of grid regulation capacity adequacy proposed in this study can comprehensively and accurately describe the transmission capacity of the grid under long-term supply and demand, which can provide more accurate reference information for power system security and planning.