Improving Synchronous Generator Parameters Estimation Using $d- q$ Axes Tests and Considering Saturation Effect

Fundamentals of parameter estimation of synchronous generator (SG) have already been presented in different standards such as IEEE Std. 115. The first proposed methods require short circuit tests and/or some tests for which the synchronous generator should be out of service. In recent reports, however, to avoid the shortcomings of former methods, partial load rejection tests on
$d- q$
axes have been recommended to estimate the electrical parameters of SG such as different reactances and time constants. In this paper, it is first shown that the standard well-known methods are valid when there is no saturation effect. Therefore, a new method is proposed to improve SG parameters estimation taking into account the saturation effect. The proposed method uses saturation curve parameters, rotor angle, and analytical equations of the SG alongside the load rejection tests results. To show the accuracy and precision of the proposed method, it is applied to experimental data of an 80 MVA gas turbine unit, and the results are discussed.