Enhanced control of a DFIG-based system by sliding-mode control method during network disturbances

Abstract

This paper presents a new method for control of the grid-side converter (GSC) of a doubly fed induction generator (DFIG) system under unbalanced and harmonic grid voltage conditions. The proposed controller is designed based on the sliding-mode control (SMC) method, and operates better than the current ones as the power quality of the DFIG is improved. The fluctuations in electromagnetic torque and stator reactive power are removed by control of the rotor-side converter (RSC). In addition, the GSC keeps the DC-link voltage at a reference value and mitigates not only fluctuations but also oscillations in steady injected active power to the network. Therefore, the output power of the system is free from any fluctuation and distortion. The control algorithm is implemented in the stationary reference frame and it is not necessary to extract voltage or current sequences in either of the converters. The proposed control algorithms are also robust against parameter variations and the resulting dynamic response is fast. The simulation results confirm the validity of the mentioned advantages and the effectiveness of the proposed method.