Direct-model predictive control for fault ride-through capability enhancement of DFIG

This paper proposes a direct-model predictive con trol (DMPC) system for fault-ride through (FRT) abil ity improvement of doubly-fed induction generators (DFIGs) in variable-speed wind energy conversion systems (WECSs). The proposed DMPC scheme considers the discrete states of the 2-level volt age source converter and its future performance is predicted for the next sampling period. Subse quently, the switching action that minimizes a pre defined cost function is selected to be applied in the next sampling instant. The proposed FRT method utilizes the rotor inertia of the wind turbine and DFIG to store the surplus energy during voltage dips/faults. Therefore, no extra hardware compo nents is required. Furthermore, the proposed FRT method improves the ability of the DFIG to deliver active and reactive power to the grid during vari ous voltage dips/faults. Simulation results are pre sented to validate the proposed FRT method under symmetrical and asymmetrical voltage dips/faults.