Maximum Power Extraction and Pitch Angle Control for Offshore Wind Turbine with Open-Loop Hydraulic Transmission

Abstract

This paper aims to extract optimal power from a hydraulic floating wind turbine using torque control and pitch control. When wind speed is below rated value, a nonlinear fuzzy controller is designed to capture maximum wind energy through regulating the displacement of hydraulic pump fixed in nacelle. When wind speed is above rated value, to achieve the pitch angle control and guarantee that the generation system safely works, an adaptive fuzzy controller is built and the stability of the control system has been analyzed through Lyapunov criterion. In order to validate the feasibility of the proposed controllers, the system has been simulated in Matlab/simulink under random wind speeds. The results show that as the wind speed is below the rated value the power coefficient has been kept to the optimal value. Furthermore, the maximum output power has been held near to rated value as the wind speed is above the rated value. Keywords-Offshore Wind Turbine; Hydraulic Transmission; Nonlinear Fuzzy Controller; Adaptive Fuzzy Controller; Optimal Power Extraction