Direct adaptive torque control for maximizing the power captured by wind turbine in partial loading condition

Abstract

In this paper, a direct adaptive control approach is used to track the tip speed ratio (TSR) of wind turbine to maximize the power captured during the below rated wind speed operation. Assuming a known optimum value of TSR, the deviation of actual TSR from the optimum one is mathematically expressed as TSR tracking error. Since the actual TSR is not a measurable quantity, this expression for TSR tracking error is linearized and simplified to express it in terms of wind speed and rotor speed, where rotor speed can easily be measured. Although it is possible to measure the wind speed with high accuracy using LiDAR, using it raises the overall cost of wind turbine installation; hence, a method to estimate the wind speed is also proposed. The adaptive controller operates on this simplified TSR tracking error to drive it to zero and to keep the TSR constant at desired optimum value. The performance of the proposed control scheme is illustrated by implementing and simulating it in the National Renewable Energy Laboratory 5MW wind turbine model and comparing the results with the existing baseline fixed gain controller. Copyright © 2015 John Wiley & Sons, Ltd.

Adaptive pitch control of wind turbine for load mitigation under structural uncertainties

“…We employ the NREL offshore 5-MW benchmark wind turbine in this research, which is a popular choice in related studies [2,18,20,26]. This is a three-bladed, upwind, variable-speed variable bladepitch-to-feather-controlled horizontal axis turbine [2].…”

“…Balas et al developed an adaptive Disturbance Tracking Control (DTC) technique to track the optimal tip speed ratio based on a wind speed estimator with the linearized CART model [25]. Magar and Balas employed a simplified model in adaptive control design, and demonstrated performance robustness in tracking optimal tip speed ratio under various operating conditions [26].…”

“…Here we have ˆŷ can be arbitrary, positive-definite matrices. In order to guarantee the stability, we must have the following conditions satisfied[5,26,34]: All inputs to the reference model are bounded. In this research, the pitch angle input bound is guaranteed by the pitch angle limits (0-90 degree).…”

“…is stable. In this research, all the eigenvalues of closed-loop system are placed in the left-half s-plane.The selection of parameters in Equations(25) and(26) is based on the control objective which is to regulate the generator speed according to the closed-loop DAC output and achieve simultaneously load mitigation. Since we have considered the disturbance rejection in reference model by DAC approach, the gain z G in Equation (25) is chosen to be 0.…”

Adaptive State Feedback—Theory and Application for Wind Turbine Control

“…The direct measurement of wind speed is either expensive when LiDAR is used or unreliable when a cup anemometer is used; therefore, we extended this theory to incorporate wind-speed estimation based on the lower-order linear model of wind turbines [21,22]. We demonstrate the effectiveness of this extended control system with wind-speed estimation through controller implementation and simulation on the National Renewable Energy Laboratory's (NREL's) 5 MW nonlinear wind turbine model [23]. In this paper, we present the stability analysis of the proposed extension of the adaptive controller.…”