Experimental and numerical investigation of non-predictive phase-control strategies for a point-absorbing wave energy converter

Lopes, Mário; Hals, Jørgen; Gomes, R.P.F.; Moan, Torgeir; Gato, L.M.C.; Falcão, António F. de O.

doi:10.1016/j.oceaneng.2009.01.015

Cited by 88 publications

(31 citation statements)

References 16 publications

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“…This paper further demonstrates that the accumulator can improve the power output characteristics of the machine greatly, and the correct configuration parameter of storage can improve the stability and rapidity of output energy [16]. Fig.…”

Section: Introductionmentioning

confidence: 63%

Experimental and Simulative Study on Accumulator Function in The Process of Wave Energy Conversion

Zhang

Liu

Luo

et al. 2016

Polish Maritime Research

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Section: Introductionmentioning

confidence: 63%

Experimental and Simulative Study on Accumulator Function in The Process of Wave Energy Conversion

Zhang

Liu

Luo

et al. 2016

Polish Maritime Research

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“…In this case, the latching duration (or equivalently, the unlatching time) can be optimized to synchronize the peak of the velocity with the peak of the excitation force [25] or to maximize the absorbed power [9]. In addition, a number of different strategies have been proposed to determine the best unlatching time for polychromatic waves; see, e.g., [26][27][28][29][30][31][32]. In this study, the body is unlatched at the instant when the excitation force passes a chosen threshold (threshold unlatching [30]).…”

Section: Latching Controlmentioning

confidence: 99%

“…In addition, a number of different strategies have been proposed to determine the best unlatching time for polychromatic waves; see, e.g., [26][27][28][29][30][31][32]. In this study, the body is unlatched at the instant when the excitation force passes a chosen threshold (threshold unlatching [30]). Here, we choose zero as the threshold value.…”

Section: Latching Controlmentioning

confidence: 99%

Control-Informed Geometric Optimization of Wave Energy Converters: The Impact of Device Motion and Force Constraints

2015

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Abstract:The energy cost for producing electricity via wave energy converters (WECs) is still not competitive with other renewable energy sources, especially wind energy. It is well known that energy maximising control plays an important role to improve the performance of WECs, allowing the energy conversion to be performed as economically as possible. The control strategies are usually subsequently employed on a device that was designed and optimized in the absence of control for the prevailing sea conditions in a particular location. If an optimal unconstrained control strategy, such as pseudo-spectral optimal control (PSOC), is adopted, an overall optimized system can be obtained no matter whether the control design is incorporated at the geometry optimization stage or not. Nonetheless, strategies, such as latching control (LC), must be incorporated at the optimization design stage of the WEC geometry if an overall optimized system is to be realised. In this paper, the impact of device motion and force constraints in the design of control-informed optimized WEC geometries is addressed. The aim is to verify to what extent the constraints modify the connection between the control and the optimal device design. Intuitively, one might expect that if the constraints are very tight, the optimal device shape is the same regardless of incorporating or not the constrained control at the geometry optimization stage. However, this paper tests the hypothesis that the imposition of constraints will limit the control influence on the optimal device shape. PSOC, LC and passive control (PC) are considered in this study. In addition, constrained versions of LC and PC are presented.

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“…2, is encapsulated by the following relationship: (15) which can be equivalently written in the time domain as (16) where is the inverse Fourier of (17) When , the radiation resistance goes to zero and, therefore, tends to the constant value . This means that the transform relationship in (17) is only valid in a generalized sense and, more correctly (18) where is the Dirac delta function.…”

Section: A Analysis Of Noncausalitymentioning

confidence: 99%

“…Note that simpler suboptimal, but at the same time effective, causal control solutions, that do not require predictions, have also been proposed in [15] and [16].…”

Section: Introductionmentioning

confidence: 99%

A Study of the Prediction Requirements in Real-Time Control of Wave Energy Converters

Fusco

Ringwood

2012

IEEE Trans. Sustain. Energy

101

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Abstract-It is widely acknowledged that real-time control of wave energy converters (WECs) can benefit from prediction of the excitation force. The prediction requirements (how far ahead into the future do we need to predict?) and the achievable predictions (how far ahead can we predict?) are quantified when unconstrained reactive control is implemented. The fundamental properties of the floating system that influence the length of the required forecasting horizon, as well as the achievable prediction, are characterized. The possibility of manipulating the control, based on prior knowledge of the wave spectral distribution, is also proposed for the reduction of the prediction requirements, such that they are within the range of predictability offered by simple stochastic predictors. The proposed methodology is validated on real wave data and heaving buoys with different geometries.

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Experimental and numerical investigation of non-predictive phase-control strategies for a point-absorbing wave energy converter

Cited by 88 publications

References 16 publications

Experimental and Simulative Study on Accumulator Function in The Process of Wave Energy Conversion

Experimental and Simulative Study on Accumulator Function in The Process of Wave Energy Conversion

Control-Informed Geometric Optimization of Wave Energy Converters: The Impact of Device Motion and Force Constraints

A Study of the Prediction Requirements in Real-Time Control of Wave Energy Converters

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