This paper proposes a simple adaptive controller for pitch angle control of the variable speed wind turbine. The aim of the controller is to keep the speed of the generator at the rated value when the wind speed is above the nominal value. The controller contains two components: one is output feedback component for stable purpose, the other is adaptive component to cancel the effect of nonlinearities, system uncertainties, and external disturbances. The controller does not need information of system parameters and wind speed then it is robust to the system uncertainties as well as wind speed varying. Moreover, this controller is quite simple, so it is easy for implementation. The stability of the closed loop and the convergence of the adaptive law is mathematically proven via Lyapunov theory. The effectiveness of the given scheme is verified via simulation under two scenarios: step wind speed and random wind speed. Also, the comparisons are done between proposed adaptive controller, the corresponding nonadaptive controller, and the PID controller. The simulation results show that, for both cases, the given adaptive controller has the best responses with low steady state error of rotor speed, low overshoot, and smooth output power
