Control co-design mooring optimisation for wave energy systems: a three-tethered point absorber case

This study aims to optimise the productivity of a wave energy converter (WEC) as a function of the mooring lines orientation, within a control co-design framework, based on the principle of impedance-matching. Within the outlined case study, a three-tethered point absorber (PA) is investigated and evaluated on a representative wave scatter, where the wave directionality is included within the optimisation problem. The mooring optimal pattern is achieved by approaching the station-keeping problem in terms of a linearised model. As such, to achieve effective computation of the complete mooring model, a single-line frequency response is identified (starting from a target, high-fidelity model), and parameterised as a function of the line orientation. The results arising from the corresponding optimisation problem effectively shows the relevance of the mooring pattern orientation, and the significant influence of mooring effects within control synthesis.