Research Papers: Ocean Renewable Energy

Effect of Axial Acceleration on Drivetrain Responses in a Spar-Type Floating Wind Turbine

[+] Author and Article Information
Amir R. Nejad

Department of Marine Technology,
Norwegian University of Science
and Technology (NTNU),
Trondheim NO-7491, Norway
e-mail: Amir.Nejad@ntnu.no

Erin E. Bachynski

Department of Marine Technology,
Norwegian University of Science
and Technology (NTNU),
Trondheim NO-7491, Norway
e-mail: erin.bachynski@ntnu.no

Torgeir Moan

Department of Marine Technology,
Norwegian University of Science
and Technology (NTNU),
Trondheim NO-7491, Norway
e-mail: Torgeir.Moan@ntnu.no

1Corresponding author.

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received December 2, 2017; final manuscript received August 8, 2018; published online January 17, 2019. Assoc. Editor: Sungmoon Jung.

J. Offshore Mech. Arct. Eng 141(3), 031901 (Jan 17, 2019) (7 pages) Paper No: OMAE-17-1209; doi: 10.1115/1.4041996 History: Received December 02, 2017; Revised August 08, 2018

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 0.2–0.3 g, 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 modeled 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 the 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 multibody system (MBS) analysis tool. The local responses on bearings are then obtained from MBS analysis and postprocessed 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.

Copyright © 2019 by ASME
Your Session has timed out. Please sign back in to continue.


Zamora-Rodriguez, R. , Gomez-Alonso, P. , Amate-Lopez, J. , De-Diego-Martin, V. , Dinoi, P. , Simos, A. N. , and Souto-Iglesias, A. , 2014, “Model Scale Analysis of a TLP Floating Offshore Wind Turbine,” ASME Paper No. OMAE2014-24089.
Goupee, A. J. , Kimball, R. W. , and Dagher, H. J. , 2017, “Experimental Observations of Active Blade Pitch and Generator Control Influence on Floating Wind Turbine Response,” Renewable Energy, 104, pp. 9–19. [CrossRef]
Nejad, A. R. , Bachynski, E. E. , Li, L. , and Moan, T. , 2016, “Correlation Between Acceleration and Drivetrain Load Effects for Monopile Offshore Wind Turbines,” Energy Procedia, 94, pp. 487–496. [CrossRef]
Nejad, A. R. , Bachynski, E. , Kvittem, M. , Luan, C. , Gao, Z. , and Moan, T. , 2015, “Stochastic Dynamic Load Effect and Fatigue Damage Analysis of Drivetrains in Land-Based and TLP, Spar and Semi-Submersible Floating Wind Turbines,” Mar. Struct., 42, pp. 137–153. [CrossRef]
Ormberg, H. , and Bachynski, E. E. , 2012, “Global Analysis of Floating Wind Turbines: Code Development, Model Sensitivity and Benchmark Study,” 22nd International Offshore and Polar Engineering Conference, Rhodes, Greece, June 17–22, pp. 366–373. https://www.onepetro.org/conference-paper/ISOPE-I-12-166
Jonkman, J. , 2010, “Definition of the Floating System for Phase IV of OC3,” National Renewable Energy Laboratory, Golden, CO, Technical Report No. NREL/TP-500-47535. https://www.nrel.gov/docs/fy10osti/47535.pdf
Jonkman, J. , Butterfield, S. , Musial, W. , and Scott, G. , 2009, “Definition of a 5-MW Reference Wind Turbine for Offshore System Development,” U.S. National Renewable Energy Laboratory, Golden, CO, Technical Report No. NREL/TP-500-38060. https://www.nrel.gov/docs/fy09osti/38060.pdf
Nejad, A. R. , Guo, Y. , Gao, Z. , and Moan, T. , 2016, “Development of a 5 MW Reference Gearbox for Offshore Wind Turbines,” Wind Energy, 19(6), pp. 1089–1106. [CrossRef]
Li, L. , Gao, Z. , and Moan, T. , 2015, “Joint Distribution of Environmental Condition at Five European Offshore Sites for Design of Combined Wind and Wave Energy Devices,” ASME J. Offshore Mech. Arct. Eng., 137(3), p. 031901. [CrossRef]
Kvittem, M. I. , and Moan, T. , 2015, “Time Domain Analysis Procedures for Fatigue Assessment of a Semi-Submersible Wind Turbine,” Mar. Struct., 40, pp. 38–59. [CrossRef]
Berger, B. , 2016, “Major Component Failure Data and Trends,” Operations and Maintenance Summit Proceedings, Toronto, ON, Canada, Feb. 24–25.
IEC, 2012, “Wind Turbines—Part 4: Standard for Design and Specification of Gearboxes,” International Electrotechnical Commission, Geneva, Switzerland, Standard No. IEC 61400-4:2012. https://www.iso.org/obp/ui/#iso:std:iec:61400:-4:ed-1:v1:en
ISO 281, 2007, “Rolling Bearings—Dynamic Load Ratings and Rating Life,” International Organization for Standardization, Geneva, Switzerland, Standard No. ISO 281:2007. https://www.iso.org/standard/38102.html
Shigley, J. E. , 2011, Shigley's Mechanical Engineering Design, McGraw-Hill, New York.
Nejad, A. R. , Gao, Z. , and Moan, T. , 2014, “On Long-Term Fatigue Damage and Reliability Analysis of Gears Under Wind Loads in Offshore Wind Turbine Drivetrains,” Int. J. Fatigue, 61, pp. 116–128. [CrossRef]


Grahic Jump Location
Fig. 1

Five-megawatt reference gearbox layout [8]

Grahic Jump Location
Fig. 2

Five-megawatt reference gearbox topology [8]

Grahic Jump Location
Fig. 3

Multibody system model of 5-MW reference gearbox [8]

Grahic Jump Location
Fig. 4

Screening of environmental conditions. Selected conditions (circles) for drivetrain analysis are indicated.

Grahic Jump Location
Fig. 5

Power spectrum of axial acceleration in different ECs

Grahic Jump Location
Fig. 6

One-hour maximum torque, axial force (Fx), tower fore-aft bending moment (My) at top and base, and load on bearing INP-A, correlated with 1-h maximum nacelle acceleration. Green, red, and blue circles show results for EC3, EC34, and EC84, respectively (in black color print EC3, EC34, and EC84 are the circles from left to right).

Grahic Jump Location
Fig. 7

INP-A force and number of cycles, EC84

Grahic Jump Location
Fig. 8

INP-A and INP-B equivalent steady load (for fatigue life) versus max. axial acceleration

Grahic Jump Location
Fig. 9

Power spectrum of INP-A radial force in different ECs

Grahic Jump Location
Fig. 10

Power spectrum of INP-B axial force in different ECs



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In