Investigation of transient models and performances for a doubly fed wind turbine under a grid fault

In order to investigate the impacts of the integration of wind farms into utilities network, it is necessary to analyze the transient performances of wind turbine generation systems (WTGS) with the appropriate transient models. According to the grid code requirements for a wind turbine with doubly fed induction generator (DFIG), the assessments of the impact on the electrical transient performances were investigated for the doubly fed wind turbine with different representations of wind turbine drive-train dynamics models, different initial operational conditions and different active crowbar trip time. Firstly, the different mathematical models of the doubly fed wind turbine were presented, including the electromagnetic transient models of DFIG, a one-mass lumped model, a two-mass shaft flexible model of the wind turbine drive train system, and the power decoupling control strategies of the grid-side converter and the rotor-side converter of DFIG. Secondly, the transient performances of the presented doubly fed wind turbine under a grid fault were compared and evaluated with different equivalent models, parameters and initial operational conditions. And thirdly, the effects of the active crowbar on the transient performances of the doubly fed wind turbine were also investigated, with the possible reasonable trip time of crowbar. The investigation have shown that the transient performances are closely correlated with the wind turbine drive train models, initial operational conditions, key parameters of wind turbine, and trip time of the crowbar circuit.