Adaptive Disturbance Tracking theory with state estimation and state feedback for region II control of large wind turbines

Abstract

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:

Infinite horizon linear quadratic tracking problem: A discounted cost function approach

“…30 As shown in Table 2, 3 scenarios are intended to apply the disturbance of load shift to areas of power system (51). Given the assumption of infinite horizon in the control strategy, the standard cost function (21) will be infinite in all 3 scenarios.…”

“…Disturbance rejection without changing the reference trajectories is not an ideal strategy in some power systems because it does not fit into the inherent duties of such systems. For example, in a wind turbine, the variations in speed or direction of wind should be tracked by the controller even if it is inconsistent with the designer's predictions in the control system [19][20][21][22][23] or in general supply and demand systems for electricity, the control system has been set for a given consumption status but any variations in consumption level should be as much as possible responded by the control system. 24,25 This is accomplished by changing the reference trajectories proportionate to the disturbance signals.…”

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

“…This section presents the summary of results obtained from the stability analysis of the proposed adaptive controller. Details of the analysis can be found in Thapa Magar and Balas, Thapa Magar and Frost.…”