Advanced Control Systems for Wave Energy Converters

Description

This submission contains several papers, a final report, descriptions of a theoretical framework for two types of control systems, and descriptions of eight real-time flap load control policies with the objective of assessing the potential improvement of annual average capture efficiency at a reference site on an MHK device developed by Resolute Marine Energy, Inc. (RME). The submission also contains an LCOE model that estimates the performance and related energy cost improvements that each advanced control system might provide and recommendations for improving DOE's LCOE model. The two types of control systems are for wave energy converters which transform data into commands that, in the case of RME's OWSC wave energy converter, provide real-time adjustments to damping forces applied to the prime mover via the power take-off system (PTO). The control theories developed were: 1) Model Predictive Control (MPC) or so-called "non-causal" control whereby sensors deployed seaward of a wave energy converter measure incoming wave characteristics and transmit that information to a data processor which issues commands to the PTO to adjust the damping force to an optimal value; and 2) "Causal" control which utilizes local sensors on the wave energy converter itself to transmit information to a data processor which then issues appropriate commands to the PTO. The two advanced control policies developed by Scruggs and Re Vision were then compared to a simple control policy, Coulomb damping, which was utilized by RME during the two rounds of ocean trials it had conducted prior to the commencement of this project. The project work plan initially included a provision for RME to conduct hardware-in-the-loop (HIL) testing of the data processors and configurations of valves, sensors and rectifiers needed to implement the two advanced control systems developed by Scruggs and Re Vision Consulting but the funding for that aspect of the project was cut at the conclusion of Budget Period 1. Accordingly, more work needs to be done to determine: a) means and feasibility of implementing real-time control; and b) added costs associated with such implementation taking into account estimated effects on system availability in addition to component costs.

Resources

Name Format Description Link
10 Paper discussing a Model Predictive Control (MPC) Code Framework for implementing feedforward controls on the RME Surge WEC, prepared by Re Vision Consulting. https://mhkdr.openei.org/files/171/MPC%20Controls%20Methodology.docx
33 Titled "Optimal Causal Control of wave energy converters (WECs) in stochastic waves -Accommodating non-linear dynamic and loss models," this paper proposes the use of Gaussian Closure to accommodate nonlinear WEC dynamics in the synthesis of the optimal feedback law to ease the modeling assumptions that must be made when determining the optimal feedback controller for an ocean WEC. https://mhkdr.openei.org/files/171/2016%20Nie%20et%20al.pdf
33 Final report discussing the investigation of eight real-time flap load control policies with the objective of assessing the potential improvement of annual average capture efficiency at a reference site, including methodology, project constraints, findings, and conclusion. This report was prepared by Resolute Marine Energy, Inc. https://mhkdr.openei.org/files/171/DE-EE0006402%20-%20Final%20report%20-%20FINAL.pdf
53 Analysis that provides a detailed estimate of the LCOE improvements associated with each of the two advanced control policies developed during the project compared to the "baseline" control policy (Coulomb damping) used in RME's previous ocean trials. https://mhkdr.openei.org/files/171/LCoE%20Analysis%20MP%208-14-16.xlsx

Tags

  • oscillating
  • report
  • receding-horizon
  • cost
  • converter
  • hydrokinetic
  • comparison
  • owsc
  • methodology
  • stochastic
  • simple
  • surge-converter
  • mhk
  • rme
  • wave
  • pto
  • re-vision-consulting
  • power-take-off
  • system
  • lcoe
  • wec
  • mpc
  • predictive
  • marine
  • ocean
  • causal-control
  • power
  • code
  • model
  • coulomb
  • swan
  • feedforward-controls
  • technology
  • resolute-marine
  • control
  • economics
  • surge
  • wwiii
  • causal
  • non-causal
  • coulomb-damping
  • model-predictive-control
  • predicted
  • energy
  • control-systems
  • non-causal-control

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