Nonlinear dynamics of a tightly moored point-absorber wave energy converter

Vicente, Pedro C.; Falcão, António F. de O.; Justino, Paulo Alexandre

doi:10.1016/j.oceaneng.2012.12.008

Cited by 54 publications

(34 citation statements)

References 23 publications

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“…(33) indicates that the PTO system should take the value of the radiation damping of the floater in order to gain the maximum power. In our calculation, the radius of the hemispherical floater is R = 5 m. Indicated by Vicente [23], the stiffness coefficient of the PTO system is chosen as K = 0.1 gS. Thus according to Eqs.…”

Section: Resultsmentioning

confidence: 99%

Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves

Zhang

Yang

2015

Applied Ocean Research

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Section: Resultsmentioning

confidence: 99%

Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves

Zhang

Yang

2015

Applied Ocean Research

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“…According to Vicente at el. [26], the stiffness of a PTO system is typically around ten percentage of the hydrostatic coefficient. Therefore, K = 0.1ρgπR 2 is adopted.…”

Section: Numerical Modellingmentioning

confidence: 99%

Wave Force Prediction Effect on the Energy Absorption of a Wave Energy Converter With Real-Time Control

Yuan

Gao

et al. 2019

IEEE Trans. Sustain. Energy

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Liang Li et al.: Wave force prediction effect on the energy absorption of a wave energy converter with real-time control Abstract-Real-time control has been widely adopted to enlarge the energy extraction of a wave energy converter (WEC). In order to implement a real-time control, it is necessary to predict the wave excitation forces in the close future. In many previous studies, the wave forces over the prediction horizon were assumed to be already known, while the wave force prediction effect has been hardly examined. In this paper, we investigate the effect of wave force prediction on the energy absorption of a heaving point-absorber WEC with real-time latching control. The real-time control strategy is based on the combination of optimal command theory and first order-one variable grey model GM(1,1). It is shown that a long prediction horizon is beneficial to the energy absorption whereas the prediction deviation reduces extracting efficiency of the WEC. Further analysis indicates that deviation of wave force amplitude has little influence on the WEC performance. It is the phase deviation that leads to energy loss. Since the prediction deviation accumulates over the horizon, a moderate horizon is thus recommended.Index Terms-real-time control, wave energy converter, energy absorption, renewable energy, wave force prediction I. IntroductionT is expected that the global demand for energy will climb up to 25 percent by 2040 and the world is pursuing economic and renewable energy sources to keep up with this considerable demand growth [1]. Among various of ocean energy resources, sea waves take the advantage of high power density and all-day availability. To extract energy from ocean waves, WECs with various operation mechanisms have been developed. Li et al. [2] showed the power output of an oscillating-body WEC installed on a spar-type floating wind turbine. Boren et al. [3] presented a testing of a scaled vertical axis pendulum WEC. He et al. [4] utilized a floater breakwater to harvest energy from the waves. Experimental study of the concept was performed.Control action is introduced to the WEC to enlarge the energy absorption and broaden the bandwidth. Babarit et al. [5] studied how the declutching control influenced the energy absorption of a WEC in regular and irregular waves. Zou et al.[6] investigated constrained and unconstrained optimal control of a heaving point-absorber. Park et al. [7] proposed an phase L. Li, Z. M. Yuan (corresponding author), and Y. Gao, are with Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, (e-mail: liang.li@strath.ac.uk; zhiming.yuan@strath.ac.uk; yan.gao@strath.ac.uk ).control by estimating the wave period using velocity and acceleration information.The latching control was first proposed by Budal and Falnes [8]. They found that one condition for maximizing energy absorption was to keep the velocity in phase with the wave excitation force. Therefore, the latching control is a kind of phase control. Hoskin and Nichols [9] used op...

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“…The PTO force is therefore applied to the WEC via the tension in the mooring line at the connection point. Examples of analysis of these types of systems include [52][53][54][55] …”

Section: Pto Forcementioning

confidence: 99%

Mathematical Modelling of Mooring Systems for Wave Energy Converters—A Review

2017

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Mathematical analysis is an essential tool for the successful development and operation of wave energy converters (WECs). Mathematical models of moorings systems are therefore a requisite in the overall techno-economic design and operation of floating WECs. Mooring models (MMs) can be applied to a range of areas, such as WEC simulation, performance evaluation and optimisation, control design and implementation, extreme load calculation, mooring line fatigue life evaluation, mooring design, and array layout optimisation. The mathematical modelling of mooring systems is a venture from physics to numerics, and as such, there are a broad range of details to consider when applying MMs to WEC analysis. A large body of work exists on MMs, developed within other related ocean engineering fields, due to the common requirement of mooring floating bodies, such as vessels and offshore oil and gas platforms. This paper reviews the mathematical modelling of the mooring systems for WECs, detailing the relevant material developed in other offshore industries and presenting the published usage of MMs for WEC analysis.

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Nonlinear dynamics of a tightly moored point-absorber wave energy converter

Cited by 54 publications

References 23 publications

Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves

Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves

Wave Force Prediction Effect on the Energy Absorption of a Wave Energy Converter With Real-Time Control

Mathematical Modelling of Mooring Systems for Wave Energy Converters—A Review

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