Fixed switching frequency scheme for current predictive control of DFIG

This paper suggests a new current predictive control algorithm for the wind-driven doubly-fed induction generator (DFIG) based on space vector modulation (SVM) with fixed switching frequency. Combining the current predictive controller and SVM has the benefits of a predictive controller, and fixing the switching frequency improves the output waveform quality. However, if classical predictive control is used, the computational burden will still be high. The proposed algorithm uses SVM to fix the switching frequency of the rotor side converter. Additionally, by using an incremental algorithm, the proposed technique prevents examining all inputs over the prediction horizon. As a result, in the proposed current predictive algorithm the computational time is significantly reduced. The detailed state-space model of DFIG and rotor side converter are used to execute the predictive algorithm. The proposed algorithm uses the rotor current to predict the next behavior of the DFIG, and then, by using SVM, the duty cycles of 2-level voltage source inverter are obtained. Finally, the proposed controller's responses are compared to those of the SVM-based field-oriented control strategy. Simulation results of the proposed controller on a two-level voltage source inverter under a balanced three-phase power system illustrate the satisfactory active and reactive power tracking and improved quality of the inverter outputs.