Method for controlling a wave-energy-converter system taking into account uncertainties

Patent metadata

Field	Value
Publication number	US-11236720-B2
Application number	US-201916580915-A
Country	US
Kind code	B2
Filing date	Sep 24, 2019
Priority date	Sep 25, 2018
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

The present invention is a method for controlling a wave-energy-converter system, wherein the gains of a control law having a proportional component are optimally determined in terms of the harvest of energy, and are robust with respect to uncertainties in the dynamics of the wave-energy-converter system. The harvest of energy is maximized for the worst case described by the uncertainties, by solving a semidefinite-positive optimization problem.

First claim

The invention claimed is:

1. A method for controlling a wave-energy-converter system that converts energy of sea swells into electrical or hydraulic energy, the wave-energy-converter system comprising at least one movable float linked to a power take-off, and the movable float making an oscillatory movement with respect to the power take-off comprising steps of:
a) measuring at least one of position, speed and acceleration of the movable float;
b) estimating the force exerted by the swell on the movable float from the measurement of at least one of position and speed of the movable float;
c) determining at least one dominant frequency of the force exerted by the swell on the movable float, by an unscented Kalman filter;
d) determining a control value for the force exerted by the power take-off on the movable float to maximize power generated by the power take-off by:
i) determining intrinsic resistance for the at least one determined dominant frequency and determining reactance of the movable float, uncertainty intervals of the intrinsic resistance and reactance of the power take-off;
ii) determining at least one coefficient of a variable-gain control law including a proportional component from a semidefinite-positive optimization of maximization of the power generated by the power take-off, the semidefinite-positive optimization accounting for the intrinsic resistance and reactance of the movable float and the uncertainty intervals of the intrinsic resistance and reactance of the power take-off; and
e) controlling the power take-off with the control value.

2. The method according to claim 1 , wherein the semidefinite-positive optimization optimizes a worst case of operation of the wave-energy-converter system, which is defined by the uncertainty intervals.

3. The method according to claim 1 , wherein the semidefinite-positive optimization determines at least impedance of the control law, and determining the coefficient of a control law from the impedance of the control law.

4. The method according to claim 3 , wherein the semidefinite-positive optimization is defined by an equation:

min

γ
,

R
c

,

X
c

⁢

{
γ
}

,

such that

[

γ

R
i

+

R
m

⁢

R
c

-

X
m

⁢

X
c

X
i

+

R
m

⁢

X
c

+

X
m

⁢

R
c

R
i

+

R
m

⁢

R
c

-

X
m

⁢

X
c

R
m

⁢

R
c

-

X
m

⁢

X
c

0

X
i

+

R
m

⁢

X
c

+

X
m

⁢

R
c

0

Assignees

• Ifp Energies Now

Inventors

• Tona Paolino
• Nguyen Hoai-Nam

Classifications

• Y02E10/30

  Energy from the sea, e.g. using wave energy or salinity gradient · CPC title

• F05B2270/705

  proportional-integral · CPC title

• G06F17/16

  Matrix or vector computation {, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization (matrix transposition G06F7/78)} · CPC title

• F03B15/00 Primary

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

• F05B2270/20

  to optimise the performance of a machine · CPC title