Identification of linear systems in the presence of nonlinear distortions

A method is presented to measure and identify a linear system in the presence of non-linear distortions. The method is based on a two step approach. In the first step the influence of non~linear systems up to degree 4 is eliminated. In the second step the remaining linear system is identified using a weighted least squares method. The kernel of the proposed technique is the excitation of the system wich a pure sinusoid Special attention is paid to the elimination of higher harmonics in the excitation signal which are due to the non-linear load of the generator.