Method for controlling a wave power system by means of an integral proportional-control law

Patent metadata

Field	Value
Publication number	US-10815959-B2
Application number	US-201816496872-A
Country	US
Kind code	B2
Filing date	Feb 26, 2018
Priority date	Mar 22, 2017
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

The present invention is a method of controlling a wave energy system (COM), wherein the force fex exerted by the waves on a mobile float of the wave energy system is estimated, then at least one dominant frequency ωex of the force exerted by the waves on the mobile float is determined using an unscented Kalman filter (UKF), and the control (COM) of the wave energy system is determined by a variable-gain PI control law whose coefficients are a function of dominant frequency ωex.

First claim

The invention claimed is:

1. A method of controlling a wave energy system that converts energy of waves into electrical or hydraulic energy, the wave energy system comprising at least one mobile float in connection with an energy converter machine, and the mobile float having an oscillating motion with respect to the converter machine, comprising steps of:
a) measuring at least one of position, velocity and acceleration of the mobile float,
b) estimating force exerted by the waves on the mobile float using the measurement of at least one of the position and velocity of the mobile float,
c) determining at least one dominant frequency of the force exerted by the waves on the mobile float using an unscented Kalman filter;
d) determining a control value of the force exerted by the converter machine on the mobile float to maximize power generated by the converter machine, by use of a variable-gain proportional integral PI control law to provide the control law with coefficients determined by use of at least one of the at least one dominant frequency of the force exerted by the waves on the mobile float; and
e) controlling the converter machine by use of the control value.

2. A method as claimed in claim 1 , wherein a proportionality coefficient of the PI control law is determined by use of an optimal load resistance curve from at least one of the at least one dominant frequency of the force exerted by the waves on the mobile float.

3. A method as claimed in claim 1 , wherein an integral coefficient of the PI control law is determined by use of an optimal load reactance curve from at least one of the at least one dominant frequency of the force exerted by the waves on the mobile float.

4. A method as claimed in claim 2 , wherein an integral coefficient of the PI control law is determined by use of an optimal load reactance curve from at least one of the at least one dominant frequency of the force exerted by the waves on the mobile float.

5. A method as claim 2 , wherein the optimal load resistance Rc and the optimal load reactance Xc are determined by solving an optimization problem as follows:

min

R
c

⁢

X
c

⁢

{

-

R
c

(

X
c

+

X
i

)

2

+

(

R
c

+

R
i

)

2

⁢

(

η
p

-

η
n

-

η
p

π

⁢

(

X
c

R
c

-

arctan
⁡

(

X
c

R
c

)

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)

}

⁢

⁢
with

⁢

{

R
i

⁡

(
ω
)

=

B
pa

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ω
)

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i

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=

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

• F03B13/16 Primary

  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

• F03B15/02

  by varying liquid flow · CPC title

• F03B15/00

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