Guerrero-Fernandez, Juan L.González-Villarreal, Oscar J.Rossiter, John Anthony2022-06-162022-06-162022-05-26Guerrero-Fernandez JL, González-Villarreal OJ, Rossiter JA. (2022) Efficiency-aware nonlinear model-predictive control with real-time iteration scheme for wave energy converters, International Journal of Control, Volume 96, Issue 8, pp. 1909-19210020-7179https://doi.org/10.1080/00207179.2022.2078424https://dspace.lib.cranfield.ac.uk/handle/1826/18034Several solutions have been proposed in the literature to maximise the harvested ocean energy, but only a few consider the overall efficiency of the power take-off system. The fundamental problem of incorporating the power take-off system efficiency is that it leads to a nonlinear and non-convex optimal control problem. The main disadvantage of the available solutions is that none solve the optimal control problem in real-time. This paper presents a nonlinear model predictive control (NMPC) approach based on the real-time iteration (RTI) scheme to incorporate the power take-off system's efficiency when solving the optimal control problem at each time step in a control law aimed at maximising the energy extracted. The second contribution of this paper is the derivation of a condensing algorithm O(N2) for ‘output-only’ cost functions required to improve computational efficiency. Finally, the RTI-NMPC approach is tested using a scaled model of the Wavestar design, demonstrating the benefit of this new control formulation.enAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Wave energy convertersnonlinear model predictive controllerreal-time iterationpower take-off-system efficiencycondensing algorithm O(N2)Article1366-5820