An electro-hydraulic digital pitch system is proposed to smooth the output power fluctuations for wind turbine. An industrial personal computer-controlled hydraulic motor with high power/mass ratio is employed to achieve the pitch control in an outer open loop of this system. An inherent feedback position control loop in this system guarantees the pitch control accuracy. A constant hydraulic circuit provides the pressure supply. System model was identified using an improved identification algorithm to deal with the nonlinearities and uncertainties associated with the pitch actions. Simulations were carried out based on practical measurements. The simulation results have verified the effectiveness and higher power control precision of this system compared to conventional pitch systems. Effectiveness of the improved identification algorithm has been also validated by simulation results．
YIN Xiu-xing, LIN Yong-gang, LI Wei, GU ya-jing, LIU Hong-wei. Control and model identification of an electro-hydraulic digital pitch system. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2014, 48(5): 777-783.
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