Kaman Thapa Magar

Adaptive Disturbance Tracking Control for Large Horizontal Axis Wind Turbines in Variable Speed Transition Operation

Renewable energy is becoming more important all over the world, and wind energy is the most important role in renewable energy right now. Many countries are producing and building wind turbines, and the turbine size is becoming larger. The larger a turbine is, the more expensive it will be. However, wind turbines will fail when overspeeding. So we need control algorithms to protect the turbine and to develop power output efficiency. The study concerns the implementation of adaptive control on a Horizontal Axis Wind Turbine (HAWT). This paper focuses on the implementation of adaptive control in the Transition Region between Region 2 and Region 3. For Region 2, Adaptive Disturbance Tracking Control (DTC) with a certain tracking ratio will ensure the wind turbine has maximum power capture. Using the same Adaptive DTC in the Transition Region, but with a switching mechanism for different tracking ratios, the wind turbine will have smooth performance for connecting Region 2 and Region 3.

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

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.

Direct adaptive control for individual blade pitch control of wind turbines for load reduction

In this article, a theory of adaptive disturbance rejection control is used to design an individual blade pitch controller to reduce the loading in a utility-scale wind turbine. The goal of the adaptive disturbance rejection control is to regulate the blade pitch angle individually to reduce the asymmetrical loading in blade due to vertical wind shear and also to reject the unnecessary disturbance introduced by the wind turbulence. The applicability of the theory is illustrated by implementing the controller in the National Renewable Energy Laboratory’s 5-MW nonlinear, high-fidelity wind turbine model and simulating it in MATLAB/Simulink.

Adaptive control of inter-area oscillations in wind-integrated power systems using distributed parameter control methods

This paper presents a preliminary study using adaptive control theory to damp inter-area oscillations in power systems through controlling wind farm that is injecting power into the system. The power system is modeled as a distributed parameter system using a first order hyperbolic wave equation, which represents the dynamics of an aggregate rotor model for a system of coupled swing equations. A direct adaptive controller is used to stabilize the power swing in the face of disturbances using power injected from an alternate source like a wind farm.

Large Wind Turbine in Variable Speed Transition Operation: Adaptive Disturbance Tracking Control

The transition region control problem for wind turbines occurs while the wind speed varies from Region II to Region III and vice versa. This is the phase when both speed and torque must change separately to get the rated rotor speed and rated rotor torque when the wind speed reaches its rated value. Adaptive Disturbance Tracking Control (ADTC) theory was developed previously to track a desired Tip Speed Ratio (TSR) and hence optimize the power production in Region II of the wind turbine. In this paper we further extended this theory for transition region control, and present numerical results on a NREL’s 5 MW offshore turbine model.

Adaptive Disturbance Tracking Control for Large Horizontal Axis Wind Turbines with Disturbance Estimator in Region II Operation

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).

Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab

This study presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instability case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.

Adaptive Disturbance Tracking Control With Wind Speed Reduced Order State Estimation for Region II Control of Large Wind Turbines

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.Copyright

Smooth Transitioning of Wind Turbine Operation between Region II and Region III with Adaptive Disturbance Tracking Control

In large wind turbines, direct switching between Region II and Region III controllers lacks smooth operation while moving from one region to another. The Transition Region is a region between Region II and Region III which ensures this smoothness of operation and achieves the rated generator torque at rated speed while switching Region III controller. In this paper, we use the theory of Adaptive Disturbance Tracking Control (ADTC) with wind speed and partial state estimation, and state feedback to achieve this goal. To ensure the rated torque while switching to Region III when wind speed increases from below rated to rated value, the generator torque is varied linearly with the generator speed, whereas to achieve rated generator speed at Region III, the tracking ratio (Q) is linearly adapted based on the estimated wind speed. The proposed scheme is implemented and simulated on the National Renewable Energy Laboratory (NREL)s 5 MW onshore wind turbine model.

Adaptive Pitch Control for Speed Regulation of Floating Offshore Wind Turbine : Preliminary Study

Because of high wind energy potential and many other advantages, offshore wind energy is drawing considerable research interest. The researches have shown that more energy can be captured if wind turbines are installed farther from the shore. For this reason, research has been done in floating type of platform and showing promising results. But, floating platform exhibits additional motions due to wind and incident waves which ultimately degrade the amount of power that can be captured, demanding more advance type of control design. Also, dynamics of wind turbine is highly complex and poorly known, which adds extra complexity in controller design. In this paper, we introduce an Adaptive Pitch Controller to regulate the rotor speed and power, and implement to NREL’s 5 MW offshore wind turbine with floating platform. We compare the simulation results with the baseline gain scheduled PID controller. The preliminary simulation results show that the performance of adaptive controller is comparable to that of baseline controller.