Abstract
A combined strategy of torque error feed-forward control and blade-pitch angle servo control is proposed to improve the dynamic power capture for wind turbine maximum power point tracking (MPPT). Aerodynamic torque is estimated using the unscented Kalman filter (UKF). Wind speed and tip speed ratio (TSR) are estimated using the Newton–Raphson method. The error between the estimated aerodynamic torque and the steady optimal torque is used as the feed-forward signal to control the generator torque. The gain parameters in the feed-forward path are nonlinearly regulated by the estimated generator speed. The estimated TSR is used as the reference signal for the optimal blade-pitch angle regulation at non-optimal TSR working points, which can improve the wind power capture for a wider non-optimal TSR range. The Fatigue, Aerodynamics, Structures, and Turbulence (FAST) code is used to simulate the aerodynamics and mechanical aspects of wind turbines while MATLAB/SIMULINK is used to simulate the doubly-fed induction generator (DFIG) system. The example of a 5 MW wind turbine model reveals that the new method is able to improve the dynamic response of wind turbine MPPT and wind power capture.
Highlights
Variable-speed wind turbines (VSWTs) have been dominating the wind power market for decades, resulting in the emergence of effective strategies to improve its power coefficient (Cp )
Some system correction methods, including the differential control based on rotor speed and feed-forward control based on aerodynamic torque and generator torque, have been applied to maximum power point tracking (MPPT) control by previous researchers [11,12,13]
Zhao et al [16] found that regulating the blade-pitch angle dynamically within a slight range, according to instantaneous tip speed ratio (TSR) could increase the power by 0.2% to 3.4% in the MPPT region
Summary
Liangwen Qi 1,2 , Liming Zheng 1,2 , Xingzhi Bai 1 , Qin Chen 1 , Jiyao Chen 1 and Yan Chen 1,2, *. Received: 29 November 2019; Accepted: 19 January 2020; Published: 23 January 2020
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