Active tower damping and pitch balancing – design, simulation and field test

Duckwitz, Daniel; Shan, Martin

doi:10.1088/1742-6596/555/1/012030

Cited by 8 publications

(7 citation statements)

References 1 publication

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“…It has been demonstrated that the tower fore‐aft bending couples with the blade flap‐wise bending moments as well as the tower side‐side bending interconnects with the blade edgewise bending moments. The tower fore‐aft and side‐side bending moments contribute to most of the tower bottom fatigue damage, of which the contribution of tower fore‐aft bending exceeds 99% . Therefore, the analysis in this paper focuses on the damping of first flap‐wise bending moments and first fore‐aft tower vibrations together using multivariable control design.…”

Section: Problem Formulationmentioning

confidence: 99%

“…Generally, different control structures (in terms of choice of actuators, eg, pitch only or combined pitch and generator) result in various combinations of effective forces acting on the tower top. Table shows the various possibilities of WT structural load mitigation, depending on actuator strategies . In Table ,

\times

means that this control loop is inactive and the corresponding control variant cannot be used to achieve the load reduction of the corresponding column elment, and

\sqrt

denotes the opposite.…”

Section: Problem Formulationmentioning

confidence: 99%

“…An extra generator torque can be used to mitigate the tower side‐side mode from the tower side‐side acceleration . The most general approach for the standard tower load mitigation controller is to design a decentralized feedback loop with the measured tower top fore‐aft oscillations; this is referred to as active tower damping . From Table , we can see that the traditional active tower damping for tower fore‐aft bending moments is achieved by obtaining an additional collective pitch angle from the measured tower fore‐aft acceleration.…”

Section: Problem Formulationmentioning

confidence: 99%

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Wind turbine asymmetrical load reduction with pitch sensor fault compensation

2020

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Offshore wind turbines suffer from asymmetrical loading (blades, tower, etc), leading to enhanced structural fatigue. As well as asymmetrical loading different faults (pitch system faults etc.) can occur simultaneously, causing degradation of load mitigation performance. Individual pitch control (IPC) can achieve rotor asymmetric loads mitigation, but this is accompanied by an enhancement of pitch movements leading to the increased possibility of pitch system faults, which exerts negative effects on the IPC performance. The combined effects of asymmetrical blade and tower bending together with pitch sensor faults are considered as a ''co-design'' problem to minimize performance deterioration and enhance wind turbine sustainability. The essential concept is to attempt to account for all the ''fault effects'' in the rotor and tower systems, which can weaken the load reduction performance through IPC. Pitch sensor faults are compensated by the proposed fault-tolerant control (FTC) strategy to attenuate the fault effects acting in the control system. The work thus constitutes a combination of IPC-based load mitigation and FTC acting at the pitch system level. A linear quadratic regulator (LQR)-based IPC strategy for simultaneous blade and tower loading mitigation is proposed in which the robust fault estimation is achieved using an unknown input observer (UIO), considering four different pitch sensor faults. The analysis of the combined UIO-based FTC scheme with the LQR-based IPC is shown to verify the robustness and effectiveness of these two systems acting together and separately. KEYWORDSfault-tolerant control, individual pitch control, pitch sensor faults, wind turbine asymmetrical load reduction INTRODUCTIONAs a sustainable energy source, wind energy is taking an increasing share of the energy market to meet the growing demand for marine renewable energy. Wind energy has a significant potential for overcoming environmental pollution-related problems by reducing dependence on declining fossil fuel reserves. Wind turbines (WTs) can operate on land or offshore. Offshore WTs have large rotor diameters and high towers for high energy capture. The significant development of offshore wind power in recent years has led to a significant decrease in the levelized cost of energy (LCoE) of this form of renewable energy. However, there are two major challenges that the offshore WTs industry must face for Region 3 operation (above rated wind speed):1. Unexpected malfunction and failures of WT components will result in expensive repairs and typically months of machine unavailability, thus increasing the operation and maintenance (O&M) costs and threatening to increase the LCoE. However, offshore WT O&M are also challenged by the fact that wind farms are sometimes located 100 km offshore.

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Section: Problem Formulationmentioning

confidence: 99%

\times

means that this control loop is inactive and the corresponding control variant cannot be used to achieve the load reduction of the corresponding column elment, and

\sqrt

denotes the opposite.…”

Section: Problem Formulationmentioning

confidence: 99%

Section: Problem Formulationmentioning

confidence: 99%

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Wind turbine asymmetrical load reduction with pitch sensor fault compensation

2020

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“…Classical proportional‐integral (PI) collective pitch control (CPC) controllers only regulate the rotor without considering structural loads. In modern large‐scale wind turbines, structural loads such as tower vibration and drivetrain torsional vibration are reduced by using additional control loops for active damping at resonant frequencies . Because of the strong coupling between control modes, special attention is required when designing control loops individually for different goals to avoid performance deterioration or unstabilizing the closed‐loop system.…”

Section: Introductionmentioning

confidence: 99%

“…In modern large-scale wind turbines, structural loads such as tower vibration and drivetrain torsional vibration are reduced by using additional control loops for active damping at resonant frequencies. 3,4 Because of the strong coupling between control modes, special attention is required when designing control loops individually for different goals to avoid performance deterioration or unstabilizing the closed-loop system. To deal with the decoupling problem of single-input and single-output (SISO) approaches, advanced multiple-input and multiple-output (MIMO) controllers have been developed by wind energy researchers in order to realize multiple objectives such as regulating the rotor speed and mitigating structural loads at the same time.…”

mentioning

confidence: 99%

Structural load mitigation control for wind turbines: A new performance measure

2020

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Summary Structural loads of wind turbines are becoming critical because of the growing size of wind turbines in combination with the required dynamic output demands. Wind turbine tower and blades are therefore affected by structural loads. To mitigate the loads while maintaining other desired conditions such as the optimization of power generated or the regulation of rotor speed, advanced control schemes have been developed during the last decade. However, conflict and trade‐off between structural load reduction capacity of the controllers and other goals arise; when trying to reduce the structural loads, the power production or regulation performance may be also reduced. Suitable measures are needed when designing controllers to evaluate the control performance with respect to the conflicting control goals. Existing measures for structural loads only consider the loads without referring to the relationship between loads and other control performance aspects. In this contribution, the conflicts are clearly defined and expressed to evaluate the effectiveness of control methods by introducing novel measures. New measures considering structural loads, power production, and regulation to prove the control performance and to formulate criteria for controller design are proposed. The proposed measures allow graphical illustration and numerical criteria describing conflicting control goals and the relationship between goals. Two control approaches for wind turbines, PI and observer‐based state feedback, are defined and used to illustrate and to compare the newly introduced measures. The results are obtained by simulation using Fatigue, Aerodynamics, Structures, and Turbulence (FAST) tool, developed by the National Renewable Energy Laboratory (NREL), USA.

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Adaptive tower damping control for offshore wind turbines

2016

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This paper deals with the problem of wind turbine tower damping control design and implementation in situations where the support structure parameters vary from their nominal design values. Such situations can, in practice, occur for onshore and especially offshore wind turbines and are attributed to aging, turbine installation, scour or marine sand dunes phenomena and biofouling. Practical experience of wind turbine manufacturing industry has shown that such effects are most easily quantified in terms of the first natural frequency of the turbine support structure. The paper brings forward a study regarding the amount to which nominal tower damping controller performance is affected by changes in the turbine natural frequency. Subsequently, an adaptive tower damping control loop is designed using linear parameter‐varying control synthesis; the proposed tower damping controller depends on this varying parameter which is assumed throughout the study to be readily available. An investigation of the fatigue load reduction performance in comparison with the original tower damping control approach is given for a generic three‐bladed horizontal‐axis wind turbine. Copyright © 2016 John Wiley & Sons, Ltd.

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Active tower damping and pitch balancing – design, simulation and field test

Cited by 8 publications

References 1 publication

Wind turbine asymmetrical load reduction with pitch sensor fault compensation

Wind turbine asymmetrical load reduction with pitch sensor fault compensation

Structural load mitigation control for wind turbines: A new performance measure

Adaptive tower damping control for offshore wind turbines

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