Pseudospectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction
Abstract
The aim of this study is to describe a procedure to maximize the powertoload ratio of a novel wave energy converter (WEC) that combines an oscillating surge wave energy converter with variable structural components. The control of the powertakeoff torque will be on a wavetowave 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 timeaveraged absorbed power and surge foundation loads while assuming that the WEC motion remains sinusoidal. Previous work using pseudospectral 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 pseudospectral optimal control indicate that a unit reduction in timeaveraged power can be accompanied by a greater reduction in surgefoundationmore »
 Authors:

 National Renewable Energy Lab. (NREL), Golden, CO (United States)
 Publication Date:
 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 (EE4W); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Water Power Technologies Office
 OSTI Identifier:
 1357747
 Alternate Identifier(s):
 OSTI ID: 1415660
 Report Number(s):
 NREL/JA500065123
Journal ID: ISSN 00298018
 Grant/Contract Number:
 AC3608GO28308
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Ocean Engineering
 Additional Journal Information:
 Journal Volume: 137; Journal Issue: C; Journal ID: ISSN 00298018
 Publisher:
 Elsevier
 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; psuedospectral control
Citation Formats
Tom, Nathan M., Yu, Yi Hsiang, Wright, Alan D., and Lawson, Michael J. Pseudospectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction. United States: N. p., 2017.
Web. doi:10.1016/j.oceaneng.2017.03.027.
Tom, Nathan M., Yu, Yi Hsiang, Wright, Alan D., & Lawson, Michael J. Pseudospectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction. United States. doi:https://doi.org/10.1016/j.oceaneng.2017.03.027
Tom, Nathan M., Yu, Yi Hsiang, Wright, Alan D., and Lawson, Michael J. Tue .
"Pseudospectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction". United States. doi:https://doi.org/10.1016/j.oceaneng.2017.03.027. https://www.osti.gov/servlets/purl/1357747.
@article{osti_1357747,
title = {Pseudospectral control of a novel oscillating surge wave energy converter in regular waves for power optimization including load reduction},
author = {Tom, Nathan M. and Yu, Yi Hsiang and Wright, Alan D. and Lawson, Michael J.},
abstractNote = {The aim of this study is to describe a procedure to maximize the powertoload ratio of a novel wave energy converter (WEC) that combines an oscillating surge wave energy converter with variable structural components. The control of the powertakeoff torque will be on a wavetowave 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 timeaveraged absorbed power and surge foundation loads while assuming that the WEC motion remains sinusoidal. Previous work using pseudospectral 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 pseudospectral optimal control indicate that a unit reduction in timeaveraged power can be accompanied by a greater reduction in surgefoundation force.},
doi = {10.1016/j.oceaneng.2017.03.027},
journal = {Ocean Engineering},
number = C,
volume = 137,
place = {United States},
year = {2017},
month = {4}
}
Web of Science