Survey of the mechanisms of power take-off (PTO) devices of wave energy converters

Abstract

Ocean wave energy conversion as one of the renewable clean energy sources is attracting the research interests of many people. This review introduces different types of power take-off (PTO) technology of wave energy converters. The novelty of this paper is to present advantages and disadvantages of the linear direct and indirect drive PTO devices for ocean wave energy conversion. The designs and optimizations of PTO systems of ocean wave energy converters have been studied from reviewing the recently published literature. The novel mechanical designs of the PTO systems have been compared and investigated in order to increase the energy harvesting efficiency.

Recent Advances in Direct-Drive Power Take-Off (DDPTO) Systems for Wave Energy Converters Based on Switched Reluctance Machines (SRM)

“…Furthermore, direct electrical drive machines increase the overall controllability of the WEC, since modern power electronics and control systems highly improve the performance of all electrical machines. This feature is of special relevance because it permits to implement more efficient strategies that maximise the energy harvesting [14]); b hydro turbine (taken from [15]); c hydraulic (taken from Falcão [16]); d air turbine (taken from Têtu [11]; e direct electrical drive (taken from Drew et al [17]); f advanced materials (taken from Moretti et al [18]). The PTO components are indicated in red (Note that in the last case, the PTO and the prime mover are coincident, since the whole bulge-wave WEC is made of dielectric elastomer generators [DEGs]) from the ocean wave resource.…”

Low-Cost Heaving Single-Buoy Wave-Energy Point Absorber Optimization for Sardinia West Coast

“…The generator used for this prototype is a permanent magnet synchronous electrical machine, often referred to as torque motor, due to the low speed and high torque that it can provide thanks to the high number of poles. Several types of PTO have already been tested [9]. For this prototype, a direct-drive electrical generator is used, however, the hydraulic PTO should be tested in further investigations.…”

Ocean Wave Energy Converters Optimization: A Comprehensive Review on Research Directions

“…As a standard approach, regardless of the deployed mechanical equipment, the PTO system of a wave energy layout is mostly designed as a linear spring-damper system, in which generating power is related to Coulomb damping [53]. Furthermore, using linear generators can facilitate the direct drive power take-off systems [142]. For instance, Vernier hybrid machines [143], permanent magnetic synchronous generators [144], switched reluctance linear generators [145], and flux-switching permanent magnet linear generators (FSPMLGs) [146,147,148] are appropriate to directly convert irregular oscillatory wave motions into unidirectional steady rotation of the generator and produce electricity.…”

“…Because the optimization of a set of large WEC power take-off variables is a computationally costly, multi-modal, and large-scale problem, new algorithmic approaches would efficaciously reduce the computational budget. Furthermore, incorporating a smart module to set the PTO spring stiffness continuously in real-time and reducing sliding carriage friction could be another promising approach to enhancing current developments [154,142]. Since this configuration may benefit LCOE, a detailed cost trade-off study would need to be performed [152,156].…”