Increasing power capture from multibody wave energy conversion systems using model predictive control

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Abstract
This study presents an advanced control scheme capable of significantly increasing power production from wave energy conversion (WEC) systems. This control scheme uses a reactive power approach built upon a Model Predictive Control (MPC) framework and is capable of optimizing power capture while also respecting machine constraints (e.g. velocity, maximum force, etc.). The controller can also take into account body-to-body interactions to improve accuracy and maximize power across a system of devices. The result is a robust controller which requires only position and velocity as exogenous inputs. All other signals, including excitation force from the sea, are either estimated or predicted within the controller. It is applicable to any WEC (or array thereof) equipped with a power take off (PTO) which can deliver power - as opposed to absorbing alone - and it can be applied both in simulation and hardware. Results from this study show that improvements in average power capture of up to 500% vs. fixed passive damping are possible without exceeding reasonable machine constraints. These results were obtained in simulation using an array of five point absorber WECs in a realistic sea state.