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Title: Pseudo-spectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction

The aim of this study is to describe a procedure to maximize the power-to-load ratio of a novel wave energy converter (WEC) that combines an oscillating surge wave energy converter with variable structural components. The control of the power-take-off torque will be on a wave-to-wave timescale, whereas the structure will be controlled statically such that the geometry remains the same throughout the wave period. Linear hydrodynamic theory is used to calculate the upper and lower bounds for the time-averaged absorbed power and surge foundation loads while assuming that the WEC motion remains sinusoidal. Previous work using pseudo-spectral techniques to solve the optimal control problem focused solely on maximizing absorbed energy. This work extends the optimal control problem to include a measure of the surge foundation force in the optimization. The objective function includes two competing terms that force the optimizer to maximize power capture while minimizing structural loads. A penalty weight was included with the surge foundation force that allows control of the optimizer performance based on whether emphasis should be placed on power absorption or load shedding. Results from pseudo-spectral optimal control indicate that a unit reduction in time-averaged power can be accompanied by a greater reduction in surge-foundationmore » force.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5000-65123
Journal ID: ISSN 0029-8018
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Ocean Engineering
Additional Journal Information:
Journal Volume: 137; Journal Issue: C; Journal ID: ISSN 0029-8018
Publisher:
Elsevier
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
NREL Laboratory Directed Research and Development (LDRD); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
Country of Publication:
United States
Language:
English
Subject:
16 TIDAL AND WAVE POWER; oscillating surge wave energy converter; variable structures; load shedding; convex optimization; nonlinear optimization; psuedo-spectral control
OSTI Identifier:
1357747
Alternate Identifier(s):
OSTI ID: 1415660