Predictive Direct Torque Control of the PMSG and Individual Pitch Control of Wind Turbine
Date Issued
2016
Date
2016
Author(s)
Yang, Shih-Yu
Abstract
This thesis 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. Grid voltage oriented vector control was 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. On the other hand, for the modern wind turbine, the pitch control is an every important issue. The purpose of the pitch control is to maintain the rotor speed at the rated speed when the wind speed is above rated wind speed. The wind turbine’s blades are exerted the periodic loads from the wind and gravity, which may easy to let the wind turbine’s blade fatigue. The pitch control method that includes the speed regulation and reduction of bending moment’s oscillation is introduced in this thesis. The disturbance accommodating control handles the speed regulation problem. Moreover, by analysis the bending moment of the blade under the d-q transformation, the individual pitch control reduces the oscillation of bending moment.
Subjects
Grid voltage oriented vector control
individual pitch control
permanent magnet synchronous generator
predictive direct torque control
wind turbine
Type
thesis