Receding-Horizon Energy-Maximising Optimal Control of Wave Energy Systems Based on Moments

• Published in: IEEE transactions on sustainable energy Vol. 12; no. 1; pp. 378 - 386
• Main Authors: Faedo, Nicolas, Pena-Sanchez, Yerai, Ringwood, John V.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.01.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Converters; Energy; Energy absorption; energy-maximising control; Estimation; Force; Forecasting; Iron; Mathematical model; Maximization; moment-domain; Optimal control; Optimization; Real time; Real-time systems; receding-horizon; Sensitivity analysis; Wave energy; Wave excitation; Wave power; WEC
• ISSN: 1949-3029; 1949-3037
• DOI: 10.1109/TSTE.2020.3000013

In this study, we address the issue of real-time energy-maximising control for wave energy converters (WECs), by proposing a receding-horizon optimal control framework based on the concept of a moment . This approach is achieved by extending the so-called moment-based framework, recently published in the WEC literature, to effectively solve the associated optimal control problem within a finite time-horizon, allowing for real-time performance, and a straightforward inclusion of the wave excitation force <inline-formula><tex-math notation="LaTeX">\mathcal {F}_e</tex-math></inline-formula> estimation and forecasting requirements, which are intrinsic to the wave energy control application. We present a case study, based on a CorPower-like device, subject to both state and input constraints. We show that the proposed strategy can perform almost identically to the ideal performance case, where full knowledge of <inline-formula><tex-math notation="LaTeX">\mathcal {F}_e</tex-math></inline-formula> over the time-horizon is assumed available. Moreover, a sensitivity analysis is provided, addressing the impact of wave excitation force estimation and forecasting errors in the computation of the moment-based control input. Two main conclusions can be drawn from this analysis: Forecasting mismatch has a negligible impact on the overall performance of the strategy, while potential differences arising from estimating <inline-formula><tex-math notation="LaTeX">\mathcal {F}_e</tex-math></inline-formula>, in particular, phase errors, can substantially impact total energy absorption.