Direct Rotor Current-Mode Control Improves the Transient Response of Doubly Fed Induction Generator-Based Wind Turbines

The transient response is actually a critical dynamic characteristic of doubly fed induction generator-based wind turbines, especially in the presence of fast transient events, such as, for example, faults in the power system. This paper presents a direct rotor current-mode control (CMC) for the rotor-side converter of these induction generators, which is aimed to improve the transient response in relation to the dynamic performance achieved with the conventional (indirect) CMC. The theoretical study considers two grid fault scenarios, with balanced and unbalanced voltages, and presents a direct rotor CMC scheme for each situation. These control schemes are compared in terms of performance and cost with the indirect CMC schemes. The theoretical contribution of this paper is validated by means of selected simulation results from a 9-MW grid-connected wind power generation system.