Time-domain Identification of the Transfer Functions of Park’s -axis Synchronous Generator Model from Standstill Data

The design of a robust frequency converter controller for fatigue load reduction in variable speed wind turbines requires an accurate dynamic model of the electromagnetic part of the synchronous generator under investigation. In this paper a new procedure for identifying the transfer functions of Park’s -axis model of a synchronous generator has been developed. It will be shown that the parameters of this model can be easily identified from standstill time-domain data obtained from the modified step-response test. The validity of the theoretical model has been verified by comparing time-domain simulations with measurements taken from the Lagerwey LW-50/750 direct-drive synchronous generator. It can be concluded that a consistent model estimate of the electromagnetic part of the LW-50/750 generator has been obtained. Ultimate validation, however, will follow after the implementation of the designed frequency converter controller in this wind turbine.