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Title: Investigating the Impact of Power-Take-Off System Parameters and Control Law on a Rotational Wave Energy Converter's Peak-To-Average Power Ratio Reduction: Preprint

Conference ·

Due to the irregular nature of real waves, the power captured in a wave energy converter (WEC) system is highly variable. This is an important barrier to the effective use of WECs. To address this challenge, this study focuses on a rotational WEC power-take-off system in which high speed and high-efficiency generators along with a torque/power smoothing inertia element can be effectively utilized. In the first phase of this study, DOE’s reference model 3 (WEC-Sim RM3 - two-body point absorber) along with a slider-crank WEC were integrated for linear to rotational conversion. Relative motion between float and spar in RM3 was the driving force for this slider-crank WEC, which is connected to a motor/generator set through a gearbox. RM3 geometry was scaled down by 25 times to work within the limits of the physical motor/generator set used in the experimentation. Once the integration in a hardware-in-the-loop simulation environment was successfully completed, data on the PTAP ratio was collected for various wave conditions including regular and irregular waves. The control algorithm designed to keep the system in resonance with waves was able to maintain relatively high speed depending on the specific gear ratio and wave period. Initial results with hardware-in-the-loop simulations reveal that gear ratio and crank radius has a strong impact on the PTAP ratio. In addition, it was found that output power from the generator was maximized at a larger gear ratio, as the crank radius was increased.

Research Organization:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Water Power Technologies Office (EE-4W)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1668855
Report Number(s):
NREL/CP-5000-76016; MainId:6068; UUID:28a7922b-9147-ea11-9c31-ac162d87dfe5; MainAdminID:18512
Resource Relation:
Conference: Presented at the ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering, 3-7 August 2020; Related Information: 79091
Country of Publication:
United States
Language:
English