Sliding-mode control for a DFIG-based wind-power generation system with series grid-side converter under unbalanced grid voltage conditions

In this paper, the power quality in a wind power generation system is studied. It is shown that adding a Series Grid-Side Converter (SGSC) to the Doubly Fed Induction Generator (DFIG) structure and applying a suitable control algorithm will make the system able to compensate for the adverse effects of the voltage unbalance and, consequently, it can improve the power quality. In order to decrease design complexity and implement the control algorithms in the stationary reference frame, a Sliding-Mode Control (SMC) method for controlling the DFIG system with SGSC is proposed. One of the advantages of the proposed method in this paper is its robustness to parameter variations both in the DFIG and the connected network. Moreover, the designed controller leads to a fast dynamic response. It should be mentioned that a coordinated control is carried out between SGSC and the other DFIG converters. The simulation results approve the validity of the mentioned advantages and the effectiveness of the proposed method.