Comparison of fixed speed and doubly-fed induction wind turbines during power system disturbances

The dynamic modelling of large (MW) capacity fixed and variable speed induction generator wind turbines is discussed. A reduced order dynamic machine model is derived suitable for modelling both fixed speed and doubly-fed asynchronous generator wind turbines. Control schemes for variable speed turbines, using doubly-fed induction generators (DFIG), are described and simulated. Speed control characteristics and converter protection of the DFIG are implemented in the model. The operation of the models during power system disturbances such as network voltage sags and three-phase faults, as well as the possibility of network voltage instability, are investigated. Simulation results are presented using typical turbine and network data for wind farm installations.