Identification of slowly time-varying systems based on the qualitative features of transient response a frozen-time approach

A method for structural and parameter identification of a slowly time-varying systems is proposed. The frozen-time method is used in this analysis. By means of this method we obtain consecutive LTI models, which are identified in consecutive discrete instants using the Qualitative System Identification (QSI) Algorithm. The proposed algorithm models the behavior of the ODE’s coefficients means of polynomial functions. The algorithm models the variations of those coefficients though polynomials. An optimal model is obtained using Genetic Algorithms. The algorithm starts with a polynomial of second degree and tries to fit these polynomials, to the variations of the coefficients. If the degree of the polynomials is not enough it increases and repeats the process until achieving a good fit. The system was tested with simulated experiments in matlab, and then tested with the identification of a controlled experiment in a power systems laboratory.