Estimation of a global synchronous machine model using a multiple-input multiple-output estimator

In this paper, the measurement results of a series of standstill frequency-response (SSFR) tests, performed at different magnetization levels, are discussed. For each data set, an individual d-axis model is estimated, which allows seeing the variation of the different parameters as a function of saturation. A global estimator is presented which uses the different data sets to estimate one global model, including the field-to-armature turns ratio. The global estimator is based on an impedance matrix representation of the synchronous machine. This global estimator assumes that only the d-axis main inductance is saturation dependent. The individual estimated models justify this assumption. Finally, the relative additional error of the global estimated d-axis equivalent circuit with the individual estimated ones is studied. The measurement results discussed in this paper are obtained on a four-pole 130-kVA synchronous machine.