A new control problem called Disturbance Tracking Control (DTC), which arises in active control of variable speed horizontal axis wind turbines for electric power generation, was developed previously. Feedback control of a linear plant, which is persistently disturbed, must cause the plant output to track a linear function of the disturbance. This control theory is related to Tip Speed Ratio Tracking for wind turbines operating in Region II. The DTC approach was developed for fixed gain controllers where the parameters of the turbine are very well known. An adaptive version of the DTC Theory for turbines with poorly known parameters was developed previously. However, the adaptive DTC needs measurement of actual wind speed. In this paper we augmented a wind speed estimator and apply the theory to create an adaptive tip speed ratio tracking controller for a horizontal axis wind turbine generator based upon a model of the NREL Controls Advanced Research Turbine (CART).

In this paper we introduce an Adaptive Disturbance Tracking Control (ADTC) Theory and make some modifications to implement it to address Region II control problem of large wind turbines. Since ADTC requires measurement of wind speed, a wind speed and partial state estimator based on linearized lower-order model of wind turbine at Region II operating point was developed. The estimated wind speed was then used with the adaptive controller and the states were used for state feedback. The combination of partial state feedback and adaptive disturbance tracking control is implemented in National Renewable Energy Laboratory (NREL)’s 5 MW offshore wind turbine model and simulated in MATLAB/Simulink. The simulation result was then compared with existing fixed gain controller.

Abstract² A theory called Adaptive Disturbance Tracking Control (ADTC) is introduced and used to track the Tip Speed Ratio (TSR) of 5 MW Horizontal Axis Wind Turbine (HAWT).Since ADTC theory requires wind speed information, a wind disturbance generator model is combined with lower order plant model to estimate the wind speed as well as partial states of the wind turbine. In this paper, we present a proof of stability and convergence of ADTC theory with lower order estimator and show that the state feedback can be adaptive. I. INTRODUCTIONLarge wind turbines are operated in three different regions called Region I, Region II and Region III, and the available wind speed determines the region of operation. Region I is the startup region and wind speed is not sufficient to produce the power. When wind speed becomes large enough to produce the power but not enough to produce the rated power, then it operates in Region II. In Region III, wind speed is normally larger than the rated wind speed and produces the rated power.The amount of power that can be captured using wind turbine is given by [1]:Where, P is the power, A is the area of the rotor disc, C P is WKH SRZHU FRHIILFLHQW ! LV WKH DLU GHQVLW\ & and is the freestream wind velocity. The power coefficient C P is the function of tip-speed ratio DQG WKH EODGH SLWFK DQJOH 7KH 7LS 6SHHG 5DWLR 765 can be expressed as:

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