FREQUENCY-DOMAIN MODELING AND IDENTIFICATION OF NONLINEAR LOADS USINGA LEAST ERROR SQUARES ALGORITHM

Nonlinear electric loads result in harmonics in voltages and current w aveforms. This has prompted the need for more accurate models for thes e loads, in order to allow accurate prediction and mitigation of harmo nic distortion. This paper presents a general methodology for modellin g electric loads, in the frequency domain, in the presence of harmonic s. The proposed method is based on a least squares parameter estimatio n algorithm and requires advance knowledge of the harmonic contents of load voltage and current waveforms. The residual current, which resul ts from the incomplete extraction of the parameters due to the mismatc h between the voltage and the current waveforms, is also calculated. I t has been found that the order of the load transfer admittance, as we ll as the number of its parameters to be identified depend on the numb er of harmonics common between the voltage and current waveforms. The proposed algorithm is tested using actual recorded data. (C) 1997 Else vier Science S.A.