Abstract
The Laboratory Upgrade Point Absorber (LUPA) is an open-source point absorber wave energy converter (WEC) developed by Oregon State University. Its design and build were funded by the US Department of Energy and Business Oregon, commencing in 2020 and first deployed in the Large Wave Flume at the OH Hinsdale Wave Research Laboratory in Corvallis, OR, in 2022. The LUPA development team collaborated with the DOE National Marine Energy Centers (NMECs), Sandia National Laboratory (SNL), National Renewable Energy Laboratory (NREL), and private industry to inform the design. LUPA has three configurations: one-body heave-only, two-body heave-only, and two-body six degrees of freedom, representing increasing complexity for research in power take-off controls, mooring, geometry, modeling, and more. Figure 1 shows the LUPA data acquisition and real-time control system, and the device installed in the Large Wave Flume. The orange surface float has a 1-meter diameter, and the grey spar has a 2.1-meter draft. The power take-off (PTO) is a belt and sprocket driven system between the float and spar with a real-time controlled motor/generator onboard the float.
LUPA is designated as a US Department of Energy Water Power Technologies Office Signature Project. Open-source information on LUPA includes WEC-Sim, ProteusDS, and WecOptTool numerical models, real-time control code, fully detailed computer-aided drafting models, experimental data, photos, videos, and research papers. It has been laboratory tested for over 100 days, including regular and random wave experiments, system identification, center of gravity and moment of inertia tests. Users include graduate and undergraduate students, national laboratories, and TEAMER funding awardees. This depth and breadth of research topics and users have given us many successes and failures to share with the marine energy community.
This presentation is focused on the lessons learned from the past 5 years of designing, building, testing, and modeling LUPA. We will detail design changes that stem from the challenges of balancing stability, safety, ease of use, minimizing scaling and friction effects, and maximizing power capture. Issues with PTO control feedback loops, along with sensor and data collection improvements and the use of GitHub to manage control code and numerical models, will be discussed. We will highlight the experimental methods that have saved us time and money without compromising quality. Finally, we will review opportunities for future improvement and directions of LUPA.