Control of Three Degrees-of-Freedom Wave Energy Converters Using Pseudo-Spectral Methods

Abdelkhalik, Ossama; Zou, Shangyan; Robinett, III, Rush D.; Bacelli, Giorgio; Wilson, David G.; Coe, Ryan Geoffrey

doi:10.1115/1.4038860

Control of Three Degrees-of-Freedom Wave Energy Converters Using Pseudo-Spectral Methods

Journal Article · Thu Jan 18 23:00:00 EST 2018 · Journal of Dynamic Systems, Measurement, and Control

DOI:https://doi.org/10.1115/1.4038860· OSTI ID:1485469

Abdelkhalik, Ossama ^[1]; Zou, Shangyan ^[1]; Robinett, III, Rush D. ^[1]; Bacelli, Giorgio ^[2]; Wilson, David G. ^[2]; Coe, Ryan Geoffrey ^[2]

Michigan Tech Univ., Houghton, MI (United States)
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

This study presents a solution to the optimal control problem of a three degrees-of-freedom (3DOF) wave energy converter (WEC). The three modes are the heave, pitch, and surge. The dynamic model is characterized by a coupling between the pitch and surge modes, while the heave is decoupled. The heave, however, excites the pitch motion through nonlinear parametric excitation in the pitch mode. This paper uses Fourier series (FS) as basis functions to approximate the states and the control. A simplified model is first used where the parametric excitation term is neglected and a closed-form solution for the optimal control is developed. For the parametrically excited case, a sequential quadratic programming approach is implemented to solve for the optimal control numerically. Numerical results show that the harvested energy from three modes is greater than three times the harvested energy from the heave mode alone. Moreover, the harvested energy using a control that accounts for the parametric excitation is significantly higher than the energy harvested when neglecting this nonlinear parametric excitation term.

View Accepted Manuscript (DOE)

Research Organization:: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

Sponsoring Organization:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Hydropower Technology Program (EE-2B)

Grant/Contract Number:: AC04-94AL85000

OSTI ID:: 1485469

Report Number(s):: SAND--2018-12263J; 669160

Journal Information:: Journal of Dynamic Systems, Measurement, and Control, Journal Name: Journal of Dynamic Systems, Measurement, and Control Journal Issue: 7 Vol. 140; ISSN 0022-0434

Publisher:: ASMECopyright Statement

Country of Publication:: United States

Language:: English

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