Structural control of wind turbines with soil structure interaction included

Self Cite

109

Summary This paper investigates the use of a passive tuned mass‐damper‐inerter (TMDI) for vibration control of spar‐type floating offshore wind turbine towers. The TMDI is a relatively new concept as a passive vibration control device. The configuration consists of an “inerter” attached to the tuned mass, parallel to the spring and damper of a classical tuned mass damper (TMD). The inerter provides a mass amplification effect on the classical TMD. The presence of the inerter virtually increases the mass of the damper leading to greater vibration control capabilities. This enables one to achieve improved vibration control using a lighter damper. Using a lightweight damper is particularly important for an offshore wind turbine because increasing mass on top of the tower can destabilize the overall system and increase tower vibrations, as demonstrated in this paper. The development of a passive TMDI for an offshore wind turbine tower has been proposed in detail in this work. Numerical simulations have been performed and results are presented demonstrating the impressive vibration control capabilities of this new device under various stochastic wind‐wave loads. It has been shown that the TMDI has considerable advantages over the classical TMD, achieving impressive response reductions with reductions in the stroke of the tuned mass. The TMDI has been shown to be a promising candidate for replacing the classical TMD for offshore wind applications.

Section: Introductionmentioning

confidence: 99%

Vibration control of spar‐type floating offshore wind turbine towers using a tuned mass‐damper‐inerter

Sarkar

Fitzgerald

2019

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109

“…The past decade has seen structural control approaches applied to HAWTs to control vibrations in blades and towers. Passive,() semiactive,() and active() control schemes have been proposed by various researchers. However, all of these approaches share a similar weakness—They require additional hardware and control systems to be installed on the wind turbine blade or tower, and for this reason, the wind industry has been reluctant to implement many of these controllers.…”

Section: Introductionmentioning

confidence: 99%

Wavelet-based individual blade pitch control for vibration control of wind turbine blades

Fitzgerald

Staino

Basu

2018

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This paper proposes a novel individual blade pitch control strategy with the objective of reducing blade vibration. A wavelet linear quadratic regulator (LQR) control algorithm, which is an advanced modification of the conventional LQR controller, has been developed for this purpose. The formulation of the modified LQR algorithm uses the information derived from wavelet analysis of the blade response in real time to obtain the local energy distribution over frequency bands. This information, reflecting the effect of excitation on the blades, is used to design the pitch controller by updating the weighting matrices to be applied to the response energy and the control effort. The proposed control algorithm does not require a priori choice of the weights as in the classical case and calculates the gains using the weights based on the response characteristics in real time.The optimal LQR control problem is solved for each time interval with updated weighting matrices, through the Ricatti equation, leading to time-varying gain matrices. Simulations are carried out using the National Renewable Energy Laboratory's (NREL) high-fidelity FAST wind turbine simulation model. The simulations indicate that the proposed new wavelet controller achieves significant reduction in the out-of-plane response of the blades as compared with standard LQR or industry standard proportional integral (PI) controllers, at the expense of minor increases in rotational speed variability and increased pitch actuator usage.

“…As a result, variation of the structural natural frequency due to soil effects (SE) and/or damage will cause detuning of a passive TMD that is tuned to the natural frequency of the original structure. To address this issue, Fitzgerald and Basu used ATMD to control the response of the wind turbine subjected to wind loading with the SE considered. The authors found that the proposed active control scheme was promising when the SE needs to be included.…”

Section: Introductionmentioning

confidence: 99%

“…The authors found that the proposed active control scheme was promising when the SE needs to be included. However, mitigation of the monopile offshore wind turbines under wind, wave loading, and the combined SE and damage presence was not studied in Fitzgerald and Basu …”

Section: Introductionmentioning

confidence: 99%

Mitigation of offshore wind turbine responses under wind and wave loading: Considering soil effects and damage

Sun

2017

Summary The present paper studies the mitigation of monopile offshore wind turbines subjected to wind and wave loading. Soil effects (SE) and damage are considered. A semiactive tuned mass damper (STMD) capable of retuning its natural frequency and damping property in real time is utilized to mitigate the nacelle/tower top dynamic response. Based on the Euler–Lagrangian equation, an analytical model of the wind turbine coupled with an STMD is established wherein the interaction between the blades and the tower is modeled. Wind turbulence is generated via mapping a three‐dimensional wind field profile onto the rotating blades. Aerodynamic loading is computed using the blade element momentum method where the Prandtl's tip loss factor and the Glauert correction are considered. Wave loading is computed using Morison's equation together with the strip theory. The National Renewable Energy Laboratory monopile 5‐MW baseline wind turbine model is employed to examine the performance of the STMD. It is found that the SE and damage presence in the foundation or/and the tower can change the dominant frequency, thereby rendering the conventional TMD detuned and ineffective. In comparison, the STMD retuned in real time by the proposed algorithm can mitigate the nacelle/tower and foundation response more effectively with a smaller stroke. Results indicate that the STMD has significant effectiveness improvement over the TMD when the SE and/or damage are considered.