The population growth demands a greater generation of energy, an alternative is the use of small wind turbines, however, obtaining maximum wind power becomes the main challenge when there are drastic changes in wind speed. The angle of the blades rotates around its longitudinal axis to control the effect of the wind on the rotation of the turbine, a proportional-integral controller (PI) for this angle achieves stability and precision in a stable state but is not functional with severe alterations in wind speed, a different response time is necessary in both cases. This article proposes a novel pitch angle controller based on auto-tuning of PI gains, for which it uses a teaching–learning based optimization (TLBO) algorithm. The wind speed and the value of the magnitude of the change are used by the algorithm to determine the appropriate PI gains at different wind speeds, so it can adapt to any sudden change in wind speed. The effectiveness of the proposed method is verified by experimental results for a 14 KW permanent magnet synchronous generator (PMSG) wind turbine located at the Universidad Autónoma de Querétaro (UAQ), Mexico.

The production of electricity by renewable means is necessary to meet the growing energy demand and to protect the environment. Wind energy is an alternative, however, in places with a limited wind resource only the installation of small horizontal Axis wind turbines (SHAWT) is profitable. At rotor height, in this size of turbines, the wind is usually unstable with gusts and turbulence due to obstacles in its path such as buildings and trees. To reduce the effects of wind, the angle of incidence of the blade with the wind must be adaptable to guarantee the nominal rotation speed. The pitch angle is the angle of blade rotation around the longitudinal axis is commonly regulated with a Proportional-Integral-Derivative (PID) feedback controller, which works correctly when the wind is stable, but not when the wind presents drastic changes in speed, as a faster response speed is required. To correct this problem, this article presents a PID controller with automatic adjustment of the gain values and offering different response times for which a fuzzy logic controller (FLC) is used. The membership functions of the FLC are determined from the measurement of the wind speed at a calculated distance, so it is possible to anticipate the response of the actuator to the arrival of a wind gust to the rotor. The algorithm is implemented in 14 kW SHAWT where the difference of performance versus a conventional controller is quantified.

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