I. Introduction
Wind turbines (WTs) are evolved from the early constant-speed into the current variable-speed constant-frequency turbines due the advantages of good dynamic performance, ability to track the maxim power, and uncoupled regulation of real/imaginary power. It was reported in [1] that DFIGs are usually utilized in current wind farms in comparison with other generators, due to their catchy features of variable-speed ability with a reduced-scale back-to-back (BTB) converter (i.e. 30% of the DFIG nominal power) and lower losses. Ordinarily, DFIGs are controlled by the field-oriented control (FOC) or voltage-oriented control (VOC) principles based on proportional-integrator (PI) controllers [1]. Usually, PI regulators demonstrate good response in steady-state operations. However, slow dynamics and linear nature are the main drawbacks [2].