Controle individual de passo para turbinas eólicas utilizando controlador adaptativo

Abstract

This Master Thesis deals with the problem of reducing the resulting asymmetrical mechanical loads on the structure of large wind turbines, with horizontal axis and three blades, by means of individual pitch control of the blades. The coordinate systems are described, as well as the model of wind turbine for the design and simulation of controllers. The algorithms and control strategies most commonly used for mitigating mechanical loads are reviewed, in addition to the instrumentation necessary to this purpose. State observers are also studied, where their importance is verified to optimize the instrumentation and to give robustness to the measures of the signals, even in case of sensor failure. In order to deal with the problem of asymmetric mechanical loads, an individual pitch control system based on a Robust Model Reference Adaptive Controller (RMRAC) is proposed, with the description of its design and the simulation of the individual pitch control system using the Fatigue Aerodynamics Structures and Turbulence (FAST) software. Furthermore, a comparison is presented with the individual pitch control using a Proportional Integral controller (PI). The effectiveness of the controllers in reducing the mechanical loads on the wind turbine is evaluated by means of the measures of the signals at the strategic points of the wind turbine, according to the recommendations of the standard IEC 61400-13. By means of graphical analysis, in time and frequency domain, it is concluded that the RMRAC controller presents similar performance to the PI, but with less interference in frequencies adjacent to the frequency of interest and better adaptation to the variation of the wind speed, in the nominal wind power generation range. Thus, individual pitch control using Robust Model Reference Adaptive Controller is feasible to be implemented for the experimental evaluation.