## 1 Introduction  
The growth of a country depends on its work centers, the generation of employment, the development of their companies and services. Electricity is indispensable for each of these activities, which is why it is essential to increase energy generation and satisfy the growing demand. At the same time, it is necessary to resort to clean and renewable energies with minimal environmental damage [1]. Wind energy, for example, has achieved significant technological advances in safety and efficiency. International organizations such as The Global Wind Energy Council (GWEC) have reported that in more than 90 countries around 54 GW of wind energy have been installed in 2017, increasing the accumulated capacity to 486.8 GW, 12.6% more than in 2016 [2]. The size of wind turbines has increased in recent years; the commonly used wind turbine has a diameter of the sweeping area of 125 m able to produce up to 7.5 MW [3]. However, since 2016 it is more common to see wind turbines with a nominal power of 9.5 MW [4]. However, model V164-10, capable of generating up to 10 MW, is now available for sale and can be delivered for commercial installation after 2021 [5]. Unlike other sources of energy, the wind is not controllable, varies in time and space, and is a non-uniform and transient resource. Because man cannot control the randomness of the wind, it is necessary to use a variable speed turbine, thus making the most of this natural resource at all times. Since these turbines can change their rotation speed, to follow changes in wind speed, it follows that for each wind speed there is an ideal rotation speed, which is called optimal Tip Speed Ratio (TSR), and is different for each wind turbine [6]. The complexity of modern wind turbines forces that its control systems ensure safe and efficient operation. The angle of the blade, torque of generator and the grid side controller are the main parameters that must be controlled. The objective of these control systems is to maximize energy production, mitigate static and dynamic mechanical loads and ensure a continuous supply of energy to the grid [7]. The rotation of the blade to modify the angle of incidence between the direction of the wind and the blade, can be done with a shared conductor for all the blades, or independently. The angle is zero when the wind speed is less than nominal and increases when the wind speed exceeds nominal value. This pitch control can reduce the load on the drive train and the structure of the tower, which leads to a longer installation life [8; 9]. The torque control of the generator allows varying the speed of the turbine rotor applying the strategy of point of maximum power (MPPT), to extract as much energy as possible from the wind flow. With changes in wind speed, the rotor torque increases or decreases, so the generator torque must be the shock absorber for the turbine to turn at optimum speed [7]. The grid-side controller controls the electronic switching of the stator and rotor voltages to produce the desired voltage frequencies, therefore, it controls the active and reactive power supplied to the network [10]. The definition of the control objectives depends on the operating regions of the wind turbine. These are closely related to the wind speed and one can identify four operating regions according to the wind speed. Region I represents the wind speed that the rotor cannot move, so the rotation speed is zero. When the rotor begins to rotate, it enters region II, and this region is limited by the starting speed and wind speed where the generator rotates at its nominal speed. The objective of control in this region is to maximize energy production through MPPT strategies. Region III starts from the nominal speed to the stopping speed, which is the design speed limit and is required to stop rotation for safety. To maintain the constant nominal rotation speed, the pitch control is used.