Research Papers: Ocean Renewable Energy

Wind Turbine Controller to Mitigate Structural Loads on a Floating Wind Turbine Platform

[+] Author and Article Information
Paul A. Fleming

National Wind Technology Center,
National Renewable Energy Laboratory,
Golden, CO 80305
e-mail: paul.fleming@nrel.gov

Antoine Peiffer

Principle Power Inc.,
2321 4th Street,
Berkeley, CA 94710
e-mail: apeiffer@principlepowerinc.com

David Schlipf

Wind Energy Technology Institute,
Hochshule Flensburg University of Applied Sciences,
Hochschule Flensburg, Kanzleistraße 91–93,
24943 Flensburg, Germany
e-mail: david.schlipf@hs-flensburg.de

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 August 17, 2016; final manuscript received January 15, 2019; published online March 20, 2019. Assoc. Editor: Yin Lu Young. The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes.

J. Offshore Mech. Arct. Eng 141(6), 061901 (Mar 20, 2019) (9 pages) Paper No: OMAE-16-1097; doi: 10.1115/1.4042938 History: Received August 17, 2016; Accepted January 15, 2019

This paper summarizes the control design work that was performed to optimize the controller of a wind turbine on the WindFloat structure. The WindFloat is a semisubmersible floating platform designed to be a support structure for a multimegawatt power-generating wind turbine. A controller developed for a bottom-fixed wind turbine configuration was modified for use when the turbine is mounted on the WindFloat platform. This results in an efficient platform heel resonance mitigation scheme. In addition, several control modules, designed with a coupled linear model, were added to the fixed-bottom baseline controller. The approach was tested in a fully coupled nonlinear aero-hydro-elastic simulation tool in which wind and wave disturbances were modeled. This testing yielded significant improvements in platform global performance and tower-base bending loading.

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Fig. 1

WindFloat prototype in Portugal

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Fig. 2

Performance of baseline controller

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Fig. 3

Power spectral density of the tower fore-aft bending and platform pitch for the turbulent wind of Fig. 2. The vertical lines highlight key frequencies: dashed lines, platform pitching mode on the left, tower fore-aft bending mode on right, and two solid bands for the wave region, and black is the range of wave frequencies. (a) Tower fore-aft bending and (b) platform pitch angle.

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Fig. 4

Relative locations and color code for key spectral locations used in this paper

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Fig. 5

Open-loop control functions for the platform and nacelle control loops: (a) platform control and (b) nacelle control

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Fig. 6

Block diagram of the pitch control system including platform pitch control with nacelle velocity feedback

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Fig. 7

Time domain results of 6 m/s simulations

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Fig. 8

PSDs of key signals for simulation at 6 m/s (left: (a), (c), and (e)) and 9 m/s (right: (b), (d), and (f)): (a) blade pitch angle at 6 m/s, (b) blade pitch angle at 9 m/s, (c) platform pitching at 6 m/s, (d) platform pitching at 9 m/s, (e) tower fore-aft bending at 6 m/s, and (h) tower fore-aft bending at 9 m/s

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Fig. 9

PSDs of key signals for simulation at 13 m/s (left: (a), (c), and (e)) and 19 m/s (right: (b), (d), and (f)): (a) blade pitch angle at 13 m/s, (b) blade pitch angle at 19 m/s, (c) platform pitching at 13 m/s, (d) platform pitching at 19 m/s, (e) tower fore-aft bending at 13 m/s, and (f) tower fore-aft bending at 19 m/s

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Fig. 10

DEL value of the tower fore-aft bending across simulations (percent change from the baseline is indicated)

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Fig. 11

Standard deviations of blade pitch rate across simulations (percent change from the baseline is indicated). For 6 m/s and 9 m/s, there is no pitch activity for the baseline controller, so percent change is not indicated.

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Fig. 12

PSD of rotor speed for the 19 m/s case



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