Design of support structures for offshore wind turbines

Tempel, Jan van der

doi:10.2495/978-1-84564-205-1/17

Cited by 80 publications

(121 citation statements)

References 8 publications

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“…Thus, a lower natural frequency means that more energy can create resonant behavior increasing fatigue damage. 1 On the other hand, it might also affect the higher modes of the support structure making them coincide with some of the higher order rotor harmonics, for example, 6P, 9P. Numerical analysis has shown that the natural frequencies are notably affected by scour.…”

Section: Introductionmentioning

confidence: 99%

“…The current practice is to design the wind turbine support structure in such a way that the tower fundamental resonance does not coincide with the fundamental rotational (1P) and blade passing (3P for three-bladed turbines) frequencies of the rotor. 1 However, the higher order rotor harmonics might still coincide with higher modes of the support structure inducing important vibrations and consequently reducing the fatigue-life. Experiments performed by the Maritime Research Institute Netherlands (MARIN) also confirmed that breaking waves could induce significant oscillations and accelerations in the turbine.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Devriendt

Magalhães

Weijtjens

et al. 2014

Structural Health Monitoring

135

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This article will present and discuss the approach and the first results of a long-term dynamic monitoring campaign on an offshore wind turbine in the Belgian North Sea. It focuses on the vibration levels and modal parameters of the fundamental modes of the support structure. These parameters are crucial to minimize the operation and maintenance costs and to extend the lifetime of offshore wind turbine structure and mechanical systems. In order to perform a proper continuous monitoring during operation, a fast and reliable solution, applicable on an industrial scale, has been developed. It will be shown that the use of appropriate vibration measurement equipment together with state-of-the art operational modal analysis techniques can provide accurate estimates of natural frequencies, damping ratios, and mode shapes of offshore wind turbines. The identification methods have been automated and their reliability has been improved, so that the system can track small changes in the dynamic behavior of offshore wind turbines. The advanced modal analysis tools used in this application include the poly-reference least squares complex frequency-domain estimator, commercially known as PolyMAX, and the covariance-driven stochastic subspace identification method. The implemented processing strategy will be demonstrated on data continuously collected during 2 weeks, while the wind turbine was idling or parked.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Devriendt

Magalhães

Weijtjens

et al. 2014

Structural Health Monitoring

135

View full text Add to dashboard Cite

show abstract

“…The majority of offshore wind farms in Europe are installed in Nordic Sea due to its shallow water depth (less than 30m) by using the fixed support platforms (classic, spar and Tension Leg Platform -TLP) for the offshore wind turbines [11]. The development of offshore wind turbines with fixed support platforms is based on the experiences of onshore wind turbines.…”

Section: Offshore Wind Power Generationmentioning

confidence: 99%

Smart Structural Control Strategies for Offshore Wind Power Generation with Floating Wind Turbines

Luo¹,

Pacheco²,

Vidal³

et al. 2012

REPQJ

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Abstract. Offshore wind energy is one of the fastest growing powers in the field of renewable energy. An offshore wind farm situated sufficiently far away from the coast can generate more wind power and will have a longer operation life since the wind is stronger and more consistent than that on or near the coast. It can also avoid some major problems of the traditional wind farms like the visual and noise impacts and potential damage to wildlife. From the technical point of view, it is difficult to anchor the wind turbines directly on the seabed in deep water. Thus, new constructive solutions based on floating support structures are proposed. One of the main challenges is to reduce the fatigue of a floating offshore wind turbine so as to guarantee its proper functioning under the constraints imposed by the floating support structures subject to a greater range of motion than that of the fixed-bottom support structures. This paper analyzes the loads and dynamic response of floating support structures and proposes the smart control strategies for mitigating the dynamic wind and wave loads on floating wind turbines. Key wordsFloating wind turbines, offshore wind energy, smart structural control systems, analysis of dynamic loads and vibration control.

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“…Consequently, the experience of onshore wind turbines cannot be applied directly to the development of floating wind turbines. In general, the fatigue loads govern most parts of the support substructure design [11]. For these loads, the effects of wind-wave directional distribution and misalignment, damping and associated dynamic amplification, play a dominant role.…”

Section: Vibration Mitigation Using Tuned Liquid Column Damper (Tlcd)mentioning

confidence: 99%

“…The multibody dynamics representation [15]- [16] of the blades and tower and the multi-disciplinary optimization [17]- [18] can also be used, which allows for virtually unlimited degrees of freedom and easier coupling between them, but considerably slows the calculation time. The effect of support substructure motion on the strength of the blades and shafting is a key issue to be investigated for designing the wind turbine and support substructure [11]. The effect of greater motion, especially the inertia force induced by the combined rotational, translational and angular motion of the blades, needs to be precisely formulated [13].…”

Section: Vibration Mitigation Using Tuned Liquid Column Damper (Tlcd)mentioning

confidence: 99%

Semiactive control for floating offshore wind turbines subject to aero-hydro dynamic loads

Luo¹,

Bottasso²,

Karimi³

et al. 2011

REPQJ

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Abstract. Wind and wave dynamic loads might cause undesirable vibrations that affect the structure integrity and system performance of floating offshore wind turbines. This paper addresses the problem of dynamic load mitigation by using semiactive control techniques with the tuned liquid column dampers placed on the turbine's tower. The control law is formulated based on the mixed H 2 /H ∞ methods for ensuring the system stability and reliability. Furthermore, the proposed controller only uses output feedback so as to avoid the dependence on the knowledge of the states of the system.

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Design of support structures for offshore wind turbines

Cited by 80 publications

References 8 publications

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Structural health monitoring of offshore wind turbines using automated operational modal analysis

Smart Structural Control Strategies for Offshore Wind Power Generation with Floating Wind Turbines

Semiactive control for floating offshore wind turbines subject to aero-hydro dynamic loads

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