Advanced controller design for wind turbine systems

Abstract

In the modern life, the high dependence of global economic development on fossil fuels and the concern about the environmental problem have been motivating the increasing attention which is being paid to alternative methods of electricity generation. In the trend to the diversification of the resource market, wind power is the possible sustainable energy resource with good rospect, for it is clean and renewable. But we cannot fail to ignore the problem that wind energy conversion system has been always hampered by the unpredictably intermittent variability of the primary resource. For this reason, wind turbines usually work with low efficiency and have to endure heavy aerodynamic loads, which can seriously deteriorate the power quality. Wind energy conversion system is very challenging for modern industry, especially from the control system viewpoint. Wind turbines inherently exhibit nonlinear and non-minimum phase dynamics, in addition, mathematical models describing accurately their dynamic behavior are always not easy to obtain because of the particular operating conditions. The lack of accurate models must be countered by robust control strategies capable of securing stability and some performance features despite model uncertainties. The control problems are even more hallenging when turbines are able to operate at variable speed. Anyway, such type of turbine can be only best used through correlative multivariate controllers. More lately, people are more encouraged to the use of the electronic converters and mechanical actuators by the greater penetration of wind energy into the utility networks of leading states and the increasing size of such type of turbine. Static converters used as an interface to the electric grid enable variable-speed operation. In this paper, there should be a model of small wind turbine, and we can see from the detailed survey that the horizontal furling method is the most commonly used or small wind turbine in industry. Furling is used to extract the maximum power from wind through tip-speed-ratio control, so in this paper by using fuzzy controller we can accomplish that goal from controlling the turbine rotor speed, and by estimating the simulation results to conclude the advantages of fuzzy control methods.