New application of predictive direct torque control in permanent magnet synchronous generator-based wind turbine

Abstract

This paper concerns the application of the predictive direct torque control (PDTC) method to a permanent magnet synchronous generator (PMSG). In classical methods for controlling a PMSG, the sampling frequency of the controller must be precisely determined. However, the use of PDTC in this study enables three optimal duty cycles to be predicted at the moment of sampling, significantly reducing the ripple of the electromagnetic torque and the amplitude of the stator flux below those caused by conventional control methods. Therefore, the new method allows a lower sampling frequency than the traditional method. To operate the machine side converter, the DC bus capacitor voltage must be maintained within an acceptable and stable range. Voltage-oriented vector control is used to control the active power and the reactive power, which are delivered from the DC bus capacitor, as well as to control the voltage. In this study, a complete wind turbine system is considered, including a focus on the aerodynamics and structure of each wind turbine, using Fatigue, Aerodynamics, Structures and Turbulence (FAST). Also, to prevent the rotor speed of the wind turbine from exceeding the rated rotor speed too much, a very simple pitch controller system is considered.