Predictive pitch control of an electro-hydraulic digital pitch system for wind turbines based on the extreme learning machine

Abstract

An electro-hydraulic digital pitch system is proposed in this paper to regulate output power and drive-train torque for wind turbines. This pitch system is driven by an electro-hydraulic digital servo system and can be digitally controlled to regulate the blade pitch angle with relatively high control accuracy and fast response. A closed control loop of this pitch system is presented and an extreme learning machine is online trained to represent the nonlinear wind turbine characteristics in this control loop. Furthermore, a predictive pitch controller is designed to improve the final pitch control performances by using the established extreme learning machine. Comparative experimental results are presented to illustrate the achievable significant performance improvements on output power and drive-train torque regulations by using the proposed pitch system and predictive pitch controller.