Development of a 5 MW reference gearbox for offshore wind turbines

Nejad, Amir R.; Guo, Yi; Gao, Zhen; Moan, Torgeir

doi:10.1002/we.1884

Cited by 79 publications

(79 citation statements)

References 29 publications

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“…fatigue ranking procedure proposed by Nejad et al [41]. Figure 8 illustrates the fatigue damage 227 ranking of the components of the land-based 5 MW reference gearbox [12].…”

Section: Resultsmentioning

confidence: 99%

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Stochastic dynamic load effect and fatigue damage analysis of drivetrains in land-based and TLP, spar and semi-submersible floating wind turbines

et al. 2015

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This paper deals with the feasibility of using a 5 MW drivetrain which is designed for a land-based turbine, on floating wind turbines. Four types of floating support structures are investigated: spar, TLP and two semi-submersibles. The fatigue damage of mechanical components inside the gearbox and main bearings is compared for different environmental conditions, ranging from cut-in to cutout wind speeds. For floating wind turbines, representative wave conditions are also considered.All wind turbines are ensured to follow similar power curves, but differences in the control system (integral to different concepts) are allowed. A de-coupled analysis approach is employed for the drivetrain response analysis. First, an aero-hydro-servo-elastic code is employed for the global analysis. Next, motions, moments and forces from the global analysis are applied on the gearbox multi body model and the loads on gears and bearings are obtained. The results suggest that the main bearings sustain more damage in floating wind turbines than on land-based. The highest main bearing damage is observed for the spar floating wind turbine. The large wave induced axial load on the main shaft is found to be the primary reason of this high damage in the spar wind turbine. Apart from the main bearings -which are located on the main shaft outside the gearbox -other bearings and gears inside the gearbox hold damages in floating wind turbines equal or even less than in the land-based turbine. It is emphasized that the results presented in this study are based on a drivetrain with two main bearings, which considerably reduces the non-torque loads on

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“…fatigue ranking procedure proposed by Nejad et al [41]. Figure 8 illustrates the fatigue damage 227 ranking of the components of the land-based 5 MW reference gearbox [12].…”

Section: Resultsmentioning

confidence: 99%

“…In this paper, a 5 MW reference gearbox [12] Figure 2: 5 MW reference gearbox schematic layout [12]. …”

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confidence: 99%

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Stochastic dynamic load effect and fatigue damage analysis of drivetrains in land-based and TLP, spar and semi-submersible floating wind turbines

et al. 2015

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“…The results from the global analysis (accelerations, velocities, positions, and internal loads at the tower top) are used as input to the multibody model of the drivetrain. The 5-MW reference drivetrain [8] employed in this study includes a high speed gearbox with four-point support configuration. This configuration reduces the non-torque loading entering the gearbox.…”

Section: Modelsmentioning

confidence: 99%

On Tower Top Axial Acceleration and Drivetrain Responses in a Spar-Type Floating Wind Turbine

Nejad

Bachynski

Moan

2017

Volume 9: Offshore Geotechnics; Torgeir Moan Honoring Symposium

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Common industrial practice for designing floating wind turbines is to set an operational limit for the tower-top axial acceleration, normally in the range of 0.2-0.3g, which is typically understood to be related to the safety of turbine components. This paper investigates the rationality of the tower-top acceleration limit by evaluating the correlation between acceleration and drivetrain responses. A 5 MW reference drivetrain is selected and modelled on a spar-type floating wind turbine in 320 m water depth. A range of environmental conditions are selected based on the long-term distribution of wind speed, significant wave height, and peak period from hindcast data for the Northern North Sea. For each condition, global analysis using an aero-hydro-servo-elastic tool is carried out for six one-hour realizations. The global analysis results provide useful information on their own -regarding the correlation between environmental condition and tower top acceleration, and correlation between tower top acceleration and other responses of interest -which are used as input in a decoupled analysis approach. The load effects and motions from the global analysis are applied on a detailed drivetrain model in a multi-body system (MBS) analysis tool. The local responses on bearings are then obtained from MBS analysis and post-processed for the correlation study. Although the maximum acceleration provides a good indication of the wave-induced loads, it is not seen to be a good predictor for significant fatigue damage on the main bearings in this case. * Address all correspondence to this author. INTRODUCTIONFloating offshore wind turbines (FWTs) hold great promise for harvesting the wind power resource in relatively deep water (>50 m). In order to realize this potential in commercial floating wind parks, reductions in the levelized cost of produced electricity are needed. The development of rational design criteria and operational limits will allow for more efficient -yet safe -floating offshore wind turbines. At present, there is a common practice in the industry to set a limit for the maximum axial acceleration on the tower-top in the range of 0.2g-0.3g, even though this is not explicitly specified in the design codes. This limit has important consequences for platform design [1] as well as wind turbine control strategies [2].An earlier study by authors [3] evaluated the correlation of the tower top axial acceleration and drivetrain load effects for a bottom-fixed offshore wind turbine. The maximum axial acceleration in the monopile offshore wind turbine, which was below 0.1g, was found to be primarily a function of the tower motion, and the drivetrain design drivers -such as axial force, bending moment and the torque -were not necessarily correlated with the tower motion. Here, we examine the rationality of the nacelle axial acceleration limit with respect to the drivetrain responses of a floating wind turbine.Based on the results of a previous study [4] of several 5 MW FWT designs (a TLP, two semi-submersibles and ...

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“…The Chichi wave stimulate maximum acceleration at the tower top due to its highest PGA. The accelerations at the tower top are so large under seismic excitations that can affect the operation of the mechanical system in the nacelle, such as the shaft, gearbox [18]. Thus, the acceleration of OWT at the tower top under seismic loads shall be reduced in order to ensure the operation of the OWT.…”

Section: Structural Responses 321 Acceleration At the Top Of The Tmentioning

confidence: 99%

Passive Control of a Pentapod Offshore Wind Turbine Under Earthquakes by Using Tuned Mass Damper

Wang

Gao

et al. 2017

Volume 10: Ocean Renewable Energy

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The finite element model (FEM) of a pentapod offshore wind turbine (OWT) is established in the newly compiled FAST. The dynamic responses of the OWT are analyzed in detail. Further, a tuned mass damper as a passive control strategy is applied in order to reduce the OWT responses under seismic loads. The influence of the tuned mass damper (TMD) locations, mass and control frequencies on the reduction of OWT responses are investigated. A general configuration of TMD can effectively reduce the local and global responses to some degree, but due to the complexity of characteristics of the OWT structure and seismic waves, the single TMD can not obtain consistent controlling effects.

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Development of a 5 MW reference gearbox for offshore wind turbines

Cited by 79 publications

References 29 publications

Stochastic dynamic load effect and fatigue damage analysis of drivetrains in land-based and TLP, spar and semi-submersible floating wind turbines

Stochastic dynamic load effect and fatigue damage analysis of drivetrains in land-based and TLP, spar and semi-submersible floating wind turbines

On Tower Top Axial Acceleration and Drivetrain Responses in a Spar-Type Floating Wind Turbine

Passive Control of a Pentapod Offshore Wind Turbine Under Earthquakes by Using Tuned Mass Damper

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