Identication of Slowly Time-Varying Systems Based on The Qualitative Features of Transient Response A Frozen-Time Approach

A method for structural and parameter identi…cation 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 identi…ed in consecutive discrete instants using the Qualitative System Identi…cation (QSI) Algorithm. The proposed algorithm models the behavior of the ODE’s coe¢ cients means of polynomial functions. The algorithm models the variations of those coe¢ cients though polynomials. An optimal model is obtained using Genetic Algorithms. The algorithm starts with a polynomial of second degree and tries to …t these polynomials, to the variations of the coef…cients. If the degree of the polynomials is not enough it increases and repeats the process until achieving a good …t. The system was tested with the identi…cation of a controlled experiment in a power systems laboratory. Keywords: Time-varying systems, LTI systems, Genetic Algorithms, Frozen-time approximation, Gradient optimization, System Identi…cation.