Control strategies for DFIG wind turbines under grid fault conditions

The classical control techniques for regulating the active and reactive power delivery in doubly fed induction generators (DFIG), for wind power applications, are normally based on voltage oriented control (VOC) strategies. Among these algorithms, those that work in a synchronous reference frame, attached to the magnetic flux vector, became very popular. In spite of the good behaviour of such algorithms their performance depends highly on an accurate detection of the stator flux position, something that can be critical under unbalanced or distorted grid voltage conditions. This paper presents a new VOC strategy able to control the operation of a DFIG in the ¿ß reference frame, with no need of flux position estimation, something that conducts to a more simple and robust algorithm. In order to evaluate the advantages of this new control proposal, namely VOC-RRF, their performance will be compared with the response obtained with a classical VOC algorithm by means of PSCAD/EMTDC^® simulation models.