Power Set-Point Tracking of a Wave Energy Converter With Multiple Power Take-Off Units in Irregular Waves

Ocean wave energy has been regarded as a promising and sustainable power source for offshore power system. In order to handle the uncertainty and fluctuation of the wave power, the power system is generally designed to be highly dependent on short-time energy storage facilities such as battery packs. This means the cost of energy storage facility tends to dramatically increase when a large wave farm is deployed. This paper proposes a model predictive control algorithm to realise the continuous power set-point tracking of a single six-of-freedom point absorber with multiple power take-off units, to mitigate the dependence of the energy storage in offshore power supply. The key controller settings that determine the power quality of the wave energy converter are analysed over various power set-points. Furthermore, the performance of power set-point tracking is assessed over significant wave heights and peak periods. It is found that although the power set-point tracking algorithm only achieves 10-27% of power generation capacity at the expense of reducing power fluctuation, the controlled point absorber is still capable to serve as a high-quality power source in some of offshore scenarios.