Model predictive control of parametric excited pitch-surge modes in wave energy converters

Patent metadata

Field	Value
Publication number	US-10415537-B2
Application number	US-201715837885-A
Country	US
Kind code	B2
Filing date	Dec 11, 2017
Priority date	Dec 9, 2016
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A parametric excitation dynamic model is used for a three degrees-of-freedom (3-DOF) wave energy converter. Since the heave motion is uncoupled from the pitch and surge modes, the pitch-surge equations of motion can be treated as a linear time varying system, or a linear system with parametric excitation. In such case the parametric exciting frequency can be tuned to twice the natural frequency of the system for higher energy harvesting. A parametric excited 3-DOF wave energy converter can harvest more power, for both regular and irregular waves, compared to the linear 3-DOF. For example, in a Bretschneider wave, the harvested energy in the three modes is about 3.8 times the energy harvested in the heave mode alone; while the same device produces about 3.1 times the heave mode energy when using a linear 3-DOF model.

First claim

We claim:

1. A multi-resonant multiple degree-of-freedom wave energy converter, comprising:
a buoy in a water environment having a wave motion, wherein the waves impacting the buoy exert an excitation force with a plurality of excitation frequencies that causes a buoy motion in heave, surge, and pitch directions relative to a reference,
a power take-off that is configured to apply control forces in the heave, surge, and pitch directions to the buoy and harvest mechanical energy of the buoy motion,
a predictor that is configured to predict the excitation force of the wave impacting the buoy in a future time horizon, and
a controller that causes the power take-off to apply a force to the buoy to put the heave motion in resonance with the predicted wave excitation force in the heave direction and wherein the control forces in the surge and pitch directions are optimized using a model predictive control method to maximize parametric excitation of the surge-pitch motion by the heave motion.

2. The wave energy converter of claim 1 , wherein a natural frequency of the pitch-surge motion of the wave enemy converter is tuned to be approximately half of the heave motion frequency.

3. The wave energy converter of claim 1 , wherein the force in the heave direction is computed using a singular-arc control method.

Assignees

• Nat Tech & Eng Solutions Sandia Llc
• Univ Michigan Tech
• South Dakota Board Of Regents

Inventors

• Abdelkhalik Ossama
• Robinett Iii Rush D
• Zou Shangyan
• Wilson David G
• Bacelli Giorgio
• Korde Umesh
• Coe Ryan G

Classifications

• G06F1/02

  Digital function generators · CPC title

• F05B2270/20

  to optimise the performance of a machine · CPC title

• F05B2250/43

  with three degrees of freedom · CPC title

• F03B13/16

  using the relative movement between a wave-operated member, {i.e. a "wom"} and another member, {i.e. a reaction member or "rem"} · CPC title

• F03B15/00 Primary

  Controlling (controlling in general G05 {; regulation of plants characterised by the use of siphons F03B13/086}) · CPC title