Comparison of speed control strategies for maximum power tracking in a wind energy conversion system

This paper presents two different variable-speed control strategies to obtain the maximum power from wind turbines (WT). The two control strategies are composed by three regulators, which may be based on linear or nonlinear controllers. The first control strategy is composed of three standard proportional-integral (PI) regulators. The PI controllers are tuned for a specific operation mode. However, since the system is nonlinear, for different operating conditions, the values of the PI parameters may not be optimal. The second control approach includes a nonlinear (fuzzy) controller to compensate for the nonlinearity of the WT, to achieve improved speed performance under different operating points. The proposed control strategy uses a fuzzy controller and two standard PIs. The results show that in most cases the fuzzy controller obtains superior performance to that of the standard PI-based solution.