Abstract
An inherent challenge for the vast majority of wave energy converters (WECs) is the very high peak to average ratio of incident energy. This can be mitigated with various approaches and at different stages of energy capture. While ideally any mitigation would be done hydrodynamically through geometry, this is seldom possible for the significant majority of WECs. A common alternative approach is to reduce variability through electrical power smoothing, perhaps implemented with supercapacitors or batteries prior to electrical export. However, such an approach requires that the electrical subsystem be designed for the peak power. This paper describes an alternative approach specifically for hydraulic PTOs, that can dissipate additional energy and provide additional reactive force by dynamically controlled throttling of the working fluid. The presented approach enables power smoothing before the generator, allowing for the electrical system to be reduced in size. This Power Dissipation Network provides a dynamically controllable pressure drop in the hydraulic fluid, dissipating energy through heating of the fluid. This approach results in only a limited temperature rise which can be managed and transferred out of the system effectively. This approach has been developed for the Oscilla Power Triton, a two body, multi-mode wave energy converter. The design and performance is shown here using a numerical model, with work ongoing to complete a physical prototype. A reduction in peak to average power from above 10:1 to less than 5:1 has been achieved through this approach.