Enhanced FCS-MPC for DFIG Under Non-Ideal Grid Conditions

This article presents an improvement to the Model Predictive Control-Finite Control Set (MPC-FCS) applied to grid-connected Doubly-Fed Induction Generators (DFIG) for operation under distorted voltage conditions. The MPC-FCS controller uses the discrete system model to predict the future behavior of the rotor currents, minimizing a cost function based on the error between predictions and references. The proposed approach incorporates the Decoupled Double Synchronous Reference Frame Phase-Locked Loop (DDSRF-PLL), allowing precise synchronization with the grid, even in distorted voltage scenarios, and optimizing the selection of voltage vectors applied to the rotor. Experimental tests on a 3 kW/220 V DFIG bench setup demonstrated that the proposed enhancements deliver superior performance to conventional MPC-FCS, SRF-PLL, Deadbeat, and classical PI controllers. The proposed method, integrated with DDSRF-PLL, exhibited superior performance compared to the other strategies, standing out in waveform quality and dynamic response. The proposed controller ensured the highest power quality among all evaluated strategies, even under distorted grid voltage conditions. Notably, the traditional MPC-FCS control strategy failed to meet the current THD requirement of less than 5%, as specified by the IEEE Std. 519-2014. Additionally, it showed fast transient response, low overshoot, and high steady-state accuracy, outperforming MPC-FCS variations without proper synchronization and the other controllers compared. It also contributes significantly to the literature, addressing the gap in studies on the performance of classic MPC-FCS in grid-connected wind generation systems with DFIG.