Heave damping of spar platform for offshore wind turbine with heave plate

Subbulakshmi, A.; Sundaravadivelu, R.

doi:10.1016/j.oceaneng.2016.05.009

Cited by 44 publications

(13 citation statements)

References 14 publications

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“…The radius of the heave plates used in the three stabilizers is R = 7, 9, and 11 m, respectively. Considering a single heave plate was tried previously [29] to limit the heave motion of spar-supported wind turbines, the numerical model of the spar-supported turbine that is equipped with a single heave plate was developed as well for comparison. The radius of the single heave plate R = 14 m. The wind turbine models used in the numerical tests are illustrated in Figure 4.…”

Section: Tests Of the Proposed Concept Stabilizermentioning

confidence: 99%

Experimental Research for Stabilizing Offshore Floating Wind Turbines

Yang

Tian²,

Hvalbye³

et al. 2019

Energies

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Floating turbines are attracting increasing interest today. However, the power generation efficiency of a floating turbine is highly dependent on its motion stability in sea water. This issue is more marked, particularly when the floating turbines operate in relatively shallow water. In order to address this issue, a new concept motion stabilizer is studied in this paper. It is a completely passive device consisting of a number of heave plates. The plates are connected to the foundation of the floating wind turbine via structural arms. Since the heave plates are completely, rather than partially, exposed to water, all surfaces of them can be fully utilized to create the damping forces required to stabilize the floating wind turbine. Moreover, their stabilizing effect can be further amplified due to the application of the structural arms. This is because torques will be generated by the damping forces via the structural arms, and then applied to stabilizing the floating turbine. To verify the proposed concept motion stabilizer, its practical effectiveness on motion reduction is investigated in this paper. Both numerical and experimental testing results have shown that after using the proposed concept stabilizer, the motion stability of the floating turbine has been successfully improved over a wide range of wave periods even in relatively shallow water. Moreover, the comparison has shown that the stabilizer is more effective in stabilizing the floating wind turbine than single heave plate does. This suggests that the proposed concept stabilizer may provide a potentially viable solution for stabilizing floating wind turbines.

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Section: Tests Of the Proposed Concept Stabilizermentioning

confidence: 99%

Experimental Research for Stabilizing Offshore Floating Wind Turbines

Yang

Tian²,

Hvalbye³

et al. 2019

Energies

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“…The concept of heave plates arose from their application in offshore spar production platforms, where their characteristics of increasing heave added mass and damping are exploited in order to maintain heave motion within acceptable limits. In the case of a FOWT, heave plates provide increased added mass in the vertical plane that shifts the platform resonance period away from the wave and wind-induced excitation periods and increase the total damping of the platform by enhancing the vortex shedding process [1]. Some prototype designs, e.g., Windfloat [2] ( Figure 1) or a spar [3] use heave plates to stabilize the platform in pitch, thus improving the power output of the wind turbine.…”

Section: Introductionmentioning

confidence: 99%

Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines

Thiagarajan

Moreno

2020

JMSE

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The research problem discussed in this paper is of relevance to floating offshore wind turbine design, where heave plates are attached to the columns of a semi-submersible in order to improve vertical plane stability and the power output. Because of the shallow draft of these structures, the heave plates are proximal to the water surface. When subject to vertical plane motions the flow around a plate is altered by the presence of the free surface, resulting in changes in added mass and damping forces. In this paper, we present the experimental results for the added mass and damping coefficients for circular heave plates attached to a column, when oscillating in heave in the presence of oncoming waves. The results tend to indicate that applying the hydrodynamic coefficients obtained from still water experiments for a structure moving in waves may only be an approximation. For different relative phases of the wave and the motion, large variations could occur. We define a modified Keulegan—Carpenter (KC) number that depends on the relative amplitude of motion with respect to the wave. With this definition, the added mass and damping values are seen to be closer to the still water trends. However, at lower KC values, the added mass coefficients could differ by 30%, which can affect natural frequency estimates. Thus, caution needs to be exerted in the selection of hydrodynamic coefficients for heave plates oscillating in proximity to the free surface.

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“…For SSP, the most commonly utilized passive method is to install a ballast or fixed heave plate (FHP) at the bottom of the platform to increase the added mass/damping of the system. The effectiveness of using FHP for SSP heave motion mitigation has been verified through both numerical and experimental studies by many researchers . Instead of rigidly connecting the SSP and heave plate, tuned heave plate (THP) has also been developed recently to further improve the performance of the control system based on the concept of tuned mass damper (TMD), a method that is widely applied in reducing the seismic‐, wind‐, and wave‐induced vibrations of engineering structures .…”

Section: Introductionmentioning

confidence: 99%

A novel rotational inertia damper for heave motion suppression of semisubmersible platform in the shallow sea

Hao

2019

Struct Control Health Monit

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Semisubmersible platforms (SSPs) have been widely used in the offshore industries for energy exploitation. SSP is vulnerable to the heave motions, and continuous heave motions may cause fatigue damage to the structural and nonstructural members or even sinking of the platform. It is therefore imperative to suppress the undesired heave motions of SSP. In the present study, a novel hydraulic rotational inertia damper (RID), which can amplify the fluid resistance of the submerged plates, is proposed on the basis of the concept of inerter to mitigate the heave motions of SSP. Analytical studies are conducted in both the frequency and time domains to investigate the control effectiveness of the proposed method. For comparison, the responses of the SSP controlled by the commonly adopted fixed heave plate (FHP) and tuned heave plate (THP) are also calculated. Analytical results show that the proposed RID system is more effective in reducing the heave motions of SSP, and it can achieve the identical control performance of the FHP and THP systems by using a much smaller plate size, thus smaller physical mass (less than 0.8% of the mass of the heave plate in this research). Furthermore, it is found that the RID system performs better in the harsher wave conditions, and its effectiveness increases with the increase of wave height. The proposed method provides an attractive alternative to effectively and economically suppress the heave motions of SSP in the shallow sea.KEYWORDS fixed heave plate, heave motion suppression, inerter, rotational inertia damper, semisubmersible platform, tuned heave plate SSP is most widely applied due to its wider range of applicable water depth, larger deck area, and bigger payload capacity. However, the shallow draft and large pontoons of SSP may lead to the excessive heave motion to the platform. These continuous vibrations may not only result in the fatigue damage to the structural/nonstructural components but also affect the health of the crew and reduce the serviceability and efficiency of the platform. The aim of the present study is to propose a novel method to suppress the excessive heave motion of SSP in the shallow sea.Considerable research efforts have been made to suppress the adverse vibrations of offshore platforms, and various control methods have been proposed. These methods can be roughly classified as the passive, active, semiactive, and hybrid methods. 3 Compared with the other control systems, passive methods require no external energy input and are widely used in engineering practice. For SSP, the most commonly utilized passive method is to install a ballast or fixed heave plate (FHP) at the bottom of the platform to increase the added mass/damping of the system. The effectiveness of using FHP for SSP heave motion mitigation has been verified through both numerical and experimental studies by many researchers. 4,5 Instead of rigidly connecting the SSP and heave plate, tuned heave plate (THP) has also been developed recently to further improve the performance of the control ...

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Heave damping of spar platform for offshore wind turbine with heave plate

Cited by 44 publications

References 14 publications

Experimental Research for Stabilizing Offshore Floating Wind Turbines

Experimental Research for Stabilizing Offshore Floating Wind Turbines

Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines

A novel rotational inertia damper for heave motion suppression of semisubmersible platform in the shallow sea

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