Influence of the blades and the shaft rigidity of a wind turbine on the stability of the system under voltage dips

In this paper, we will study the influence of the blades and shaft´s rigidity on the stability of wind generator when a voltage dip appears. First, we present the model of the wind turbine, taking into consideration all damping coefficients. In this case the turbine will be represented by a three masses model. Then, neglecting the turbine blades´ damping model becomes two masses. Finally, considering that all connections are perfectly rigid turbine model will be represented by a single mass. The single mass model is used in most research in the field of wind generator. We will show in this work that the damping coefficients have considerable influence on the system behaviour at the onset of network faults. The phenomenon that we treat is the network´s voltage dips. We´ll use for our study, the cage induction generator and DFIG. For both structures a comparison between the results, obtained by the three kinds of models, will be presented.