Optimal Damping Profile for a Heaving Buoy Wave Energy Converter

Nolan, Gary; Ringwood, John V.; Leithead, W.E.; Butler, Shane

doi:10.3182/20100915-3-de-3008.00067

Cited by 20 publications

(17 citation statements)

References 8 publications

(9 reference statements)

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“…Conversely, another control strategy called declutching is able to control devices facing an incoming wave with period smaller than the natural period (Teillant et al 2010).…”

Section: Latching Controlmentioning

confidence: 99%

Implementation of latching control in a numerical wave tank with regular waves

Giorgi¹,

Ringwood²

2016

J. Ocean Eng. Mar. Energy

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In order to increase the overall power production efficiency of wave energy technology in the face of sea state variability, the presence of the control is mandatory. A model of the system is required to tune the controller parameters and predict the resulting performances. Even though the relevance of nonlinearities is magnified by the presence of the controller, the device model employed is usually linear. An implementation of control in a fully nonlinear simulation model is desirable, but missing. Hence, this paper proposes to use the fully nonlinear computational fluid dynamics (CFD) environment, implementing the latching control strategy in the open source software OpenFOAM. A case study has been analyzed to highlight the nonlinear behavior of a device under latching control and to evaluate the differences between linear and nonlinear simulation models. The results show that the linear model overestimates the amplitude of motion, and, as a result, the extracted power. Moreover, the choice of the optimal control parameter is significantly affected by the nonlinear effect on the natural period of the device.

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“…Conversely, another control strategy called declutching is able to control devices facing an incoming wave with period smaller than the natural period (Teillant et al 2010).…”

Section: Latching Controlmentioning

confidence: 99%

Implementation of latching control in a numerical wave tank with regular waves

Giorgi¹,

Ringwood²

2016

J. Ocean Eng. Mar. Energy

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“…It seems that higher values of a damper element do not result in higher yield unless the element is controlled. This, perhaps, explains why the optimal damping coefficients in declutching control tend to be much higher than ones for latching control (as is apparent from results in [30]). Thus, the optimization of PTO parameters should heavily depend on the control scheme intended.…”

Section: B Device Optimization For Controlmentioning

confidence: 90%

Optimal Active Control and Optimization of a Wave Energy Converter

Abraham

Kerrigan

2013

IEEE Trans. Sustain. Energy

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Abstract-This paper investigates optimal active control schemes applied to a point absorber wave energy converter within a receding horizon fashion. A variational formulation of the power maximization problem is adapted to solve the optimal control problem. The optimal control method is shown to be of a bang-bang type for a power take-off mechanism that incorporates both linear dampers and active control elements. We also consider a direct transcription of the optimal control problem as a general nonlinear program. A variation of the projected gradient optimization scheme is formulated and shown to be feasible and computationally inexpensive compared to a standard NLP solver. Since the system model is bilinear and the cost function is not convex quadratic, the resulting optimization problem is not a quadratic program. Results will be compared with an optimal command latching method to demonstrate the improvement in absorbed power. All time domain simulations are generated under irregular sea conditions.

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“…This phase condition, considered separately, forms the basis for some simple WEC phase control strategies, such as latching (Budal and Falnes, 1975;Korde, 2002;Babarit and Clement, 2006) and de-clutching (Babarit et al, 2009;Teillant et al, 2010;Wright et al, 2003).…”

Section: Wave Energy Control Fundamentalsmentioning

confidence: 99%

Control, forecasting and optimisation for wave energy conversion

Ringwood

Bacelli

Fusco

2014

IFAC Proceedings Volumes

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This paper presents an overview of the motivation, background to and state-ofthe-art in energy maximising control of wave energy devices. The underpinning mathematical modelling is described and the control fundamentals established. Two example control schemes are presented, along with some algorithms for wave forecasting, which can be a necessary requirement, due to the non-causal nature of some optimal control strategies. One of the control schemes is extended to show how cooperative control of devices in a wave farm can be beneficial. The paper also includes perspectives on the interaction between control and the broader objectives of optimal wave energy device geometry and full techno-economic optimisation of wave energy converters.

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Optimal Damping Profile for a Heaving Buoy Wave Energy Converter

Cited by 20 publications

References 8 publications

Implementation of latching control in a numerical wave tank with regular waves

Implementation of latching control in a numerical wave tank with regular waves

Optimal Active Control and Optimization of a Wave Energy Converter

Control, forecasting and optimisation for wave energy conversion

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