Pitch Control of Variable Speed Constant Frequency Wind Turbines Based on Active-disturbance-rejection Controller

Abstract

The wind turbine is a highly nonlinear system. This paper discusses the control concept of variable speed constant frequency (VSCF) wind turbines and their performances above rated wind speed. Then a new pitch controller based on active-disturbance-rejection control theory is proposed to improve the power-output quality of variable speed constant frequency wind turbines. Based on the feedback of rotational speeds, extended-state observers can obtain the disturbances as well as estimated states, which can be precisely cancelled subsequently. Also, this new pitch controller forms nonlinear algorithms to restrain state errors, which leads to the rotational speed ripple reduction. Besides, this paper carries out simulation of the controller under different wind speeds. The result shows that the controller produces good dynamic performance, good robustness and adaptability.