Summary: In this paper we studied the possibilities of adaptation of Scilab freeware computer mathematic package to the solution of special calculation problems are studied. We modeled and calculated the family of adaptive devices of automation, control and protection for smart/intellectual electric grids including renewable energy sources. We studied the possibilities of Scilab package for sequential calculating using a big number of algebraic functions, solving the systems of linear algebraic equations, analyzing of results, solving the tasks of optimization, building 2D and 3D function diagrams, etc. All calculated solutions obtained from Scilab, were analysed in comparison with the similar solutions calculated in MathCAD. The results confirm the relevance of using the Scilab package for these purposes and demonstrate some of its advantages in education, scientific research and electric engineering calculations.