Non-causal linear optimal control of wave energy converters with enhanced robustness by sliding mode control

Zhang, Yao and Li, Guang (2020) Non-causal linear optimal control of wave energy converters with enhanced robustness by sliding mode control. IEEE Transactions on Sustainable Energy, 11 (4), 2201-2209. (doi:10.1109/TSTE.2019.2952200).

Record type: Article

Abstract

Sea wave energy converter control is a non-causal optimal control problem, and the control performance relies on the accuracy of wave prediction information. However, the existing wave prediction methods, such as Auto-Regressive (AR) method, extended Kalman Filter (EKF), Artificial neural network and deterministic sea wave prediction (DSWP), inevitably introduce prediction errors. This paper presents a robust non-causal linear optimal control of wave energy converters to explicitly cope with the prediction error of sea wave prediction and simultaneously compensate the modelling uncertainty caused by wave force approximations. This is achieved by designing a non-causal linear optimal control (LOC) to maximize the energy output and a sliding mode control (SMC) to compensate unmodeled WEC dynamics and wave prediction error. The parameters of both SMC and non-causal LOC are calculated off-line, which significantly enhances the real-Time implementation of the proposed controller with reasonably low computational load. Simulation results demonstrate the efficacy of the proposed control strategy.

This record has no associated files available for download.

More information

Accepted/In Press date: 25 October 2019

Published date: 1 October 2020

Additional Information: Funding Information: Manuscript received June 11, 2019; revised September 30, 2019; accepted October 25, 2019. Date of publication November 8, 2019; date of current version September 18, 2020. This work was supported in part by a research contract from Wave Energy Scotlands Control Systems programme, in part by EPSRC grant Launch and Recovery in Enhanced Sea States (no. EP/P023002/1), and in part by Newton Advanced Fellowship (NA160436) by Royal Society. Paper no. TSTE-00646-2019. (Corresponding author: Guang Li.) The authors are with School of Engineering and Materials Sciences, Queen Mary University of London, London E1 4NS, U.K. (e-mail: yao.zhang@ qmul.ac.uk; g.li@qmul.ac.uk). Publisher Copyright: © 2010-2012 IEEE.

Keywords: modelling uncertainty, Non-causal control, prediction error, sliding mode control, wave energy converters