KEYWORD |

### Area Engineering

#### Model reduction by least-squares moment-matching for control of wave energy conversion systems

keywords CONTROL SYSTEMS, MODEL REDUCTION, MODELLING, SYSTEM DYNAMICS, WAVE ENERGY - HYDRODYNAMICS - NUMERICAL MODELLING

Reference persons NICOLAS EZEQUIEL FAEDO

Research Groups MORE Lab _ http://www.morenergylab.polito.it

Thesis type MASTER THESIS

Description Wave energy conversion devices, commonly referred to as wave energy converters (WECs), need to be

controlled in order to maximise the energy extraction from the ocean wave resource, hence directly

lowering the associated levelised cost of energy.

Control for WEC systems departs from standard regulation/tracking objectives, commonly employed in

control engineering: The objective is that of maximising energy extraction, and not that of

following/tracking a given set-point/reference. As such, the vast majority of the WEC control techniques

employ lie within the field of optimal control theory, where an associated optimal control problem

(OCP) is solved in real-time to compute the corresponding control action.

OCPs are virtually always model-based: That is, a dynamical model of the WEC system is required in

order to predict future motion, enforce constraints, and maximise the energy objective. These models

need to be parsimonious in terms of both computational and analytical complexity, in order to facilitate

real-time calculations, i.e. to be implementable.

Nonetheless, being the Navier-Stokes equations the starting point for WEC modelling, computing

control-oriented models can be a daunting task. As such, tools from the field of model reduction have

been recently applied, to provide dynamical structures which feature a ``simplified'' form compatible

with real-time control requirements, while still representing the main dynamics of the WEC system.

This project will explore the use of model reduction techniques by moment-matching, in a least squares

sense. Moment-matching-based models are essentially interpolating structures, which can match the

steady-state output of a given target model, for a defined class of input signals. These reduced models

have the capabilities of representing both short- and long-term WEC behaviour, being ideal for control

and performance assessment purposes, respectively.

See also main.pdf

Required skills Linear algebra, fundamentals of physical modelling, transfer functions, state-space systems.

Deadline 28/08/2024
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