Wave-to-Wire Model and Energy Storage Analysis of an Ocean Wave Energy Hyperbaric Converter

Garcia‐Rosa, Paula B.; Cunha, José Paulo V. S.; Lizarralde, Fernando; Estefen, Segen F.; Machado, Isaac R.; Watanabe, Edson H.

doi:10.1109/joe.2013.2260916

Cited by 49 publications

(30 citation statements)

References 28 publications

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“…The pattern of the input torque signal of the electric generator depends on the configuration of the PTO, regardless of the type of WEC. A PTO system that includes large accumulation systems, such as an overtopping device [38] or any wave-activated device with a hydraulic transmission system that includes large hydraulic accumulators [13,39], provides slowly-varying, smooth torque signals. In contrast, transmission systems directly connected to the electric generator, such as air turbines in oscillating water column devices [40], mechanical systems [14] or hydraulic systems without large accumulators [41] provide highly variable torque signals.…”

Section: Experiments Designmentioning

confidence: 99%

“…Such W2W models should include balanced parsimonious models for each stage (including nonlinear dynamics if required and considering the constraints and losses of each component), meaning that the level of detail included in the sub-models for the different stages of the W2W model is balanced. The most important aspects to be considered when modelling W2W models are reviewed in [11] for several different PTO systems (pneumatic [12], hydraulic [13], or a mechanical transmission system [14] coupled to a rotational generator, or a direct drive system with a linear generator [15]), which have been suggested in the literature for different WECs.…”

Section: Introductionmentioning

confidence: 99%

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Validating a Wave-to-Wire Model for a Wave Energy Converter—Part II: The Electrical System

2017

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Abstract:The incorporation of the full dynamics of the different conversion stages of wave energy converters (WECs), from ocean waves to the electricity grid, is essential for a realistic evaluation of the power flow in the drive train. WECs with different power take-off (PTO) systems, including diverse transmission mechanisms, have been developed in recent decades. However, all the different PTO systems for electricity-producing WECs, regardless of any intermediate transmission mechanism, include an electric generator, linear or rotational. Therefore, accurately modelling the dynamics of electric generators is crucial for all wave-to-wire (W2W) models. This paper presents the models for three popular rotational electric generators (squirrel cage induction machine, permanent magnet synchronous generator and doubly-fed induction generator) and a back-to-back (B2B) power converter and validates such models against experimental data generated using three real electric machines. The input signals for the validation of the mathematical models are designed so that the whole operation range of the electrical generators is covered, including input signals generated using the W2W model that mimic the behaviour of different hydraulic PTO systems. Results demonstrate the effectiveness of the models in accurately reproducing the characteristics of the three electrical machines, including power losses in the different machines and the B2B converter.

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Section: Experiments Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Validating a Wave-to-Wire Model for a Wave Energy Converter—Part II: The Electrical System

2017

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“…A number of W2W models have been presented in the literature for different types of WECs: overtopping converters [6], oscillating water columns (OWCs) [7], or wave-activated converters with different PTO strategies, e.g., hydraulic [8][9][10][11][12][13], mechanical [1,14], magnetic [13], or linear generators [15,16].…”

Section: Existing Wave-to-wire Modelsmentioning

confidence: 99%

A Review of Wave-to-Wire Models for Wave Energy Converters

2016

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Control of wave energy converters (WECs) has been very often limited to hydrodynamic control to absorb the maximum energy possible from ocean waves. This generally ignores or significantly simplifies the performance of real power take-off (PTO) systems. However, including all the required dynamics and constraints in the control problem may considerably vary the control strategy and the power output. Therefore, this paper considers the incorporation into the model of all the conversion stages from ocean waves to the electricity network, referred to as wave-to-wire (W2W) models, and identifies the necessary components and their dynamics and constraints, including grid constraints. In addition, the paper identifies different control inputs for the different components of the PTO system and how these inputs are articulated to the dynamics of the system. Examples of pneumatic, hydraulic, mechanical or magnetic transmission systems driving a rotary electrical generator, and linear electric generators are provided.

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“…For the given cases, a combined BEM-FD-TD analysis will take place. For a so called wave to wire (W2W) model [12], this means, that first, hydrodynamics coefficients are determined for the wetted geometry. Next, these parameters are attached to the equations of motion in the model solver, which in turn generates amplitudes of oscillation, velocities and power (energy) absorbed by the PA's in either FD or TD.…”

Section: Introductionmentioning

confidence: 99%

Computational Investigation on Various Small Array Dispositions of Generic Points Absorbers

Hernandez¹

2017

Preprint

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This thesis completion works it out to deepen into diverse modeling techniques for Point Absorbers. A combined frequency-time domain model is conceived, designed and developed in Matlab with FoRtran as a base., leading to obtain physical variables of primary importance, namely position, velocity and power to Energy net balance relationships of absorption. Integration of different degrees of freedom with heave as main executable leads in turn to a single buoy motion focus. Acquisition of the needed hydrodynamic coefficients is provided though application of NEMOH & BEMIO solvers due to the Boundary Element Methodology. Initially, this Wave-to-motion model is validated through comparison with previous experimental results for a floating cone cylinder shape (Buldra-FO3). A single, generic, vertical floating cylinder is contemplated then, that responds to the action of the passing regular waves excitation. Later, two equally sized vertical floating cylinders aligned with the incident wave direction are modeled for a variable distance between the bodies. For both unidirectional regular and irregular waves as an input in deep water, we approximate the convolutive radiation force function term through the Prony method. By changing the spatial disposition of the axisymmetric buoys, using for instance triangular or rectangular shaped arrays of three and four bodies respectively, the study delves into motion characteristics for regular waves. The results highlight efficient layouts for maximizing the energy production whilst providing important insights into their performance, revealing displacement amplification-and capture width-ratios, while deriving in possible interpretations of scenarios related to the the known park effect. These terms are encompassed by the novelty of a new conceptual Post-Processing methodology in the field, which leads to obtain an optimal distance for the separated bodies with effective energy absorption in a regular wave regime. In conclusion, this computational excursion envisions and proposes potentials fields of study, which will surely enhance new connections and link this renewable energy form.

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Wave-to-Wire Model and Energy Storage Analysis of an Ocean Wave Energy Hyperbaric Converter

Cited by 49 publications

References 28 publications

Validating a Wave-to-Wire Model for a Wave Energy Converter—Part II: The Electrical System

Validating a Wave-to-Wire Model for a Wave Energy Converter—Part II: The Electrical System

A Review of Wave-to-Wire Models for Wave Energy Converters

Computational Investigation on Various Small Array Dispositions of Generic Points Absorbers

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