A self-stabilizing point absorber wave energy converter with a top-shaped buoy and non-linear power take-off for oceanographic applications

Journal Article

Title: A self-stabilizing point absorber wave energy converter with a top-shaped buoy and non-linear power take-off for oceanographic applications

Author:

Azam, A.; Ahmed, A.; Yi, M.; Zhang, Z.; Tan, X.; Ali, A.; Li, N.

Publication Date:

November 15, 2023

Journal:

Ocean Engineering

Volume:

288

Issue:

Publisher:

Elsevier

Affiliation:

Southwest Jiaotong University, Northwestern Polytechnical University

Technology:

Wave, Point Absorber

Collection Method:

Lab Data, Modeling

Engineering:

Performance, Power Take Off

Document Access

Website:

External Link

Citation

Azam, A.; Ahmed, A.; Yi, M.; Zhang, Z.; Tan, X.; Ali, A.; Li, N. (2023). A self-stabilizing point absorber wave energy converter with a top-shaped buoy and non-linear power take-off for oceanographic applications. Ocean Engineering, 288(1) https://doi.org/10.1016/j.oceaneng.2023.116018

Abstract

Point absorber wave energy converters (PA-WECs) are considered an independent renewable energy resource in oceanographic research to study wave climate data, ocean navigation and maritime security. Their performance enhancement through optimally designed floats and power take-off (PTO) is a crucial challenge. The proposed study investigates the combined PA-WEC model, including (i) the hydrodynamic of the optimally designed top-shaped buoy, (ii) non-linear characteristics of power take-off and (iii) self-stability of PA-WEC under the real-time wave climate of XiaoMaiDao wave station, Shandong, China. The proposed mechanical power take-off comprises a double-sided rack with gear transmission and three-phase DC generators. The components of the power take-off are symmetrically oriented on both sides of the rack to make it statically and dynamically balanced for the self-stability of the PA-WEC. The floating buoy absorbs kinetic energy from waves relative to a fixed point and transfers it to the PTO system. The PTO module alters the forward and reverted strokes of heaving motion into uni-directional rotations on the output shaft, employing a mechanical gearing mechanism with one-way bearings. Subsequently, supercapacitors store the rectified electrical energy in the power conversion and storage modules. The mechanical power take-off was initially modeled in MATLAB/Simscape and verified through experimental investigations using mechanical testing and sensing machine. Secondly, the hydrodynamics of the floating buoy was studied using frequency- and time-domain simulations in ANSYS AQWA. Thirdly, the wave tank tests were performed on a 1:25 scaled buoy in a wave tank, and the test results were validated against the time-domain simulations. Finally, the combined effects of power take-off and buoy were studied on the prototype scale, and it is concluded that at 1m significant wave height, the power take-off system integrated with the Cyl-AS buoy can generate 247.76W (RMS) with PTO efficiency of η_{pto_rms} = 76.37% at PA-WEC efficiency of η_{wec_rms} = 12.10%. Installing the proposed point absorber wave energy converter system along the offshore platforms can promote the UN-SDG-2030 Agenda, specifically the 7 and 14 goals, by supplying electricity for oceanographic applications.