A greater attention must be paid to structural and dynamic problems of wind turbines in order to increase their reliability. In the present work the finite element modelling of a 5 MW wind generator is presented, developed by the substructuring technique and Component Modal Synthesis. Such an approach combines accuracy and acceptable computational cost. Natural modes and frequencies were determined by a modal analysis and some transient simulations were carried out for different wind speeds. The results are compared with those obtained with a simpler discretized lumped parameter model showing their agreement at the lower frequencies but also the less amount of information obtained with the simpler model.