A tendency to erect ever more wind turbines can be observed in order to reduce the environmental consequences of electric power generation. As a result of this, in the near future wind turbines may start to influence the behavior of electric power systems by interacting with conventional generation and loads. Therefore, wind turbine models that can be integrated into power system simulation software are needed. A model that can be used to represent all types of variable-speed wind turbines in power system dynamics simulations is presented. The modeling approach is commented upon, and models of the subsystems of which a variable speed wind turbine consists are discussed. Some results obtained after incorporation of the model in PSS/E, a widely used power system dynamics simulation software package, are presented and compared with measurements.