Constrained least squares methods for parameter tracking of power system steady-state equivalent circuits

The paper deals with the problem of the on-line parameter identification of power system harmonic equivalent circuits as seen from a bus at which a po wer electronic de,ice is connected. Recursive constrained least squares met hods are considered and models of different order are compared one to anoth er, The proposed on-line identification procedure is able to identify both equivalent impedances and ambient voltage harmonics and to track their chan ges during normal operating conditions. Numerical applications evidence the performance of the proposed methods in terms of both steady-state accuracy and responsiveness to changes of the parameter values.