Online Dynamic Parameter Estimation of Transformer Equivalent Circuit

The dynamic parameters of a transformer, including its inductances and resistances, are estimated by the application of recursive least squares routine on the measured terminal voltages and currents. The harmonic content of the measured input parameters can be included in the proposed method. The estimation is carried out while the transformer is under load. Therefore, the estimated parameters are obtained in real time conditions taking the saturation effects into account. The procedure needs no additional data and/or initial assumption. As a stable RLS routine, the U.D. Bierman´s method is used to ensure long period convergence of the parameter estimation procedure. Forgetting factors are proposed and used to accelerate the convergence of the estimation and improve the accuracy of the parameters