Modeling and Control Strategies of Directly Driven Wind Turbine with Permanent Magnet Synchronous Generator

The paper addresses the issues associated with modeling and controlling of directly driven wind turbine with permanent magnet synchronous generators (D-PMSG). A complete model of D-PMSG has been built, which includes wind turbine model, drive train model and generator model as well. In accordance with the variation of wind speed, strategies for pitch angle control and rotational speed control are developed. For the pitch angle controller, wind speed signals and generator output power are used as inputs and proportional-integral control is implemented, which directly represents the dependence of pitch angle control on wind speed. For the rotational speed controller, vector control method in the dq synchronous rotational frame is employed, where the d-axis current component is used to control reactive power and the q-axis current component to control the rotational speed. This concept offers the benefits not only of decoupling control but also of high utilization of generator capacity. The model of D-PMSG and the proposed control strategies have been realized with the engineering software, Matlab/Simulink. Simulation for the case of wind speed stepping change verifies the validity of the model and the feasibility of the control strategies.