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 power electronic device is connected. Recursive constrained least squares methods are considered and models of different order are compared one to another. The proposed on-line identification procedure is able to identify both equivalent impedances and ambient voltage harmonics and to track their changes 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.