Self-contained linear non-causal optimal control of onshore wave energy converters

Onshore wave energy converters (WECs) benefit from lower cost of installation and maintenance due to shared coastal infrastructure and ease of accessibility as compared with offshore WECs. However, it is challenging to design onshore WECs to operate optimally because of the complex hydrodynamic reflection effects from the shoreline structures they are attached to and varying incoming wave directions. This paper develops control-oriented state–space models for a single-float onshore WEC and an onshore five-float WEC array based on the device supplied by Eco Wave Power Ltd. (EWP). The models can capture wall-induced reflection effects, and the array model additionally represents inter-float hydrodynamic coupling. On top of these models, a linear non-causal optimal control (LNOC) framework is applied for both configurations. The controller integrates a Random Walk Kalman filter for wave excitation force estimation and a short-horizon Auto-Regressive (AR) wave predictor. The overall control system is computationally efficient for real-time implementation. Simulation studies show that the proposed LNOC strategy with a 300th-order AR model and a Kalman observer improves mean absorbed energy relative to a well-tuned passive damping controller by approximately 40%–72.2% for a single-float device and 18.9%–94.7% for the five-float array across a range of sea states. The influence of incoming wave directions is investigated comprehensively revealing a distinctive directional characteristic in the onshore setting: A single WEC exhibits only a minor dependence on incidence angle, whereas the array displays a much more pronounced directional sensitivity and maximum absorption occurs when incoming wave direction is parallel to the coastline.