Optimal control of wave energy converters

Journal Article · Fri Nov 18 00:00:00 EST 2016 · Renewable Energy

DOI:https://doi.org/10.1016/j.renene.2016.11.036· OSTI ID:1485454

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

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

Optimal control theory is applied to compute control for a single-degree-of-freedom heave wave energy converter. The goal is to maximize the energy extraction per cycle. Both constrained and unconstrained optimal control problems are presented. Both periodic and non-periodic excitation forces are considered. In contrast to prior work, it is shown that for this non-autonomous system, the optimal control, in general, includes both singular arc and bang-bang modes. Conditions that determine the switching times to/from the singular arc are derived. Simulation results show that the proposed optimal control solution matches the solution obtained using the complex conjugate control. A generic linear dynamic model is used in the simulations. In conclusion, the main advantage of the proposed control is that it finds the optimal control without the need for wave prediction; it only requires the knowledge of the excitation force and its derivatives at the current time.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1485454
• Report Number(s): SAND-2018-12265J; 669162
• Journal Information: Renewable Energy, Vol. 103, Issue C; ISSN 0960-1481
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

16 TIDAL AND WAVE POWER
Wave energy conversion
Singular arc control
Optimal control
Bang-bang control