Model predictive control for low-voltage ride through capability enhancement of DFIGs in variable-speed wind turbine systems

This paper proposes a finite control set-model predictive control (FCS-MPC) system for low-voltage ride through (LVRT) capability enhancement of doubly-fed induction generators (DFIGs) in variable-speed wind turbine systems (WTSs). The proposed FCS-MPC system takes the discrete states of the converter into account and the future converter performance is predicted for each sampling period. Then the optimal switching action that minimizes a predefined cost function is selected to be applied in the next sampling instant. The proposed LVRT strategy uses the DFIG-rotor inertia to store the surplus energy during the grid voltage dips. Moreover, the proposed LVRT strategy enhances the ability of the DFIG to inject active and reactive power to the grid during serious voltage dips. Simulation results are presented to validate the proposed LVRT strategy.