Order reduction of large scale DAE models

A tool for the order reduction of differential algebraic equations (DAEs) is outlined in this report. Through the use of an equation dependency analysis and nonlinear function approximation, the algebraic equations can be divided into sets that require implicit or explicit solutions. If all of the algebraic variables can be solved or approximated explicitly, the DAE becomes a set of ordinary differential equations (ODEs). As a test case for the theory, a dynamic equilibrium binary distillation column model is analyzed with the generalized approach. The index 1 DAE model of 52 differential and 233 algebraic states is reduced to an ODE set of 26 differential states. Through simulations, the resulting ODE model solution is found to be in agreement with the original DAE model solution.