Modelling and Control Tank Testing Validation for Attenuator Type Wave Energy Converter - Part II: Linear Noncausal Optimal Control and Deterministic Sea Wave Prediction Tank Testing

Abstract

Tank testing results from applying Linear non-causal optimal control (LNOC) to the Mocean M100 wave energy converter (WEC) are presented in this paper. Based on the two state-space models derived from Part I, two LNOC algorithms designed to increase power capture of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1/20$</tex-math></inline-formula> scaled M100 WEC prototype are tested separately in real-time under various irregular wave conditions. The deterministic sea wave prediction (DSWP) algorithm is employed to provide the required wave elevation/excitation force predictions for the LNOC using real-time wave measurements. Experimental data shows that the DSWP can predict the incoming waves with sufficiently high accuracy in various sea states. Compared with a well-tuned passive damper, LNOC based on a hydrodynamic model increases the power capture by up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$128\%$</tex-math></inline-formula> while LNOC based on a system identification (SysID) model increases the power capture by up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$323\%$</tex-math></inline-formula> . The technologies are transferrable. The testing procedure and the results also provide informative guidance for the tank testing of other advanced optimal controllers and their implementations on other types of WECs.