Stochastic Modeling and Pitch Angle Control of Wind Turbine Using Fuzzy Logic Based Adaptive Controller

Abstract

Wind energy, is renewable energy source, which is widely studied nowadays. Among wind turbine systems, variable wind turbine are the most preferred one, since it is most efficient and has more capability of control over wide speed area. Wind behavior determine the energy conversion process of wind turbine. Due to the randomness and intermittent nature of wind speed the energy conversation process is varied. So, to maximize the extracted energy from wind, pitch angle controller is investigated. Pitch angle control phenomena helps to run the system with higher efficiency and reliability in turbulent weather conditions (stochastic nature) and to stabilize output power at higher wind speed and optimize at lower wind speed. However, to maximize extracted energy conversion, pitch angle will tune the attack angle of a wind turbine rotor blade into or out of wind waves depending on wind speed. In this thesis fuzzy logic based adaptive controller is used to control the pitch angle of wind turbine to reduce external disturbance, robustness and uncertainty of parameters. The objective of the controller is defined as that of maintaining the rotor speed and pitch angle at suitable values depending on operating regions of wind turbine. Finally, a new method of fuzzy logic based adaptive controller is compared with conventional controller (PID) and the simulation results were analyzed. The simulation results shows that the fuzzy logic based adaptive controller can achieve better control performances than conventional pitch angle control strategies, minimizing fatigue and preventing input mechanical power to exceed the design limits.