scholarly journals Power absorption modelling and analysis of a multi‐axis wave energy converter

2021 ◽  
Author(s):  
Ming Tan ◽  
Yuhao Cen ◽  
Yuxuan Yang ◽  
Xiaodong Liu ◽  
Yulin Si ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Power Absorption

Power Absorption Modeling and Optimization of a Point Absorbing Wave Energy Converter Using Numerical Method

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Jeremiah Pastor ◽  
Yucheng Liu
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Domain Model ◽  
Boundary Element Methods ◽  
Damping Coefficient ◽  
Energy Converter ◽  
Incoming Wave ◽  
Power Absorption ◽  
Point Absorber ◽  
Spring Force

This paper presents, assesses, and optimizes a point absorber wave energy converter (WEC) through numerical modeling, simulation, and analysis. Wave energy conversion is a technology uniquely suited for assisting in power generation in the offshore oil and gas platforms. A linear frequency domain model is created to predict the behavior of the heaving point absorber WEC system. The hydrodynamic parameters are obtained with AQWA, a software package based on boundary element methods. A linear external damping coefficient is applied to enable power absorption and an external spring force is introduced to tune the point absorber to the incoming wave conditions. The external damping coefficient and external spring forces are the control parameters, which need to be optimized to maximize the power absorption. Two buoy shapes are tested and a variety of diameters and drafts are compared. Optimal shape, draft, and diameter of the model are then determined to maximize its power absorption capacity.

Balancing Power Absorption and Structural Loading for an Asymmetric Heave Wave-Energy Converter in Regular Waves

2016 ◽  
Author(s):  
Nathan M. Tom ◽  
Farshad Madhi ◽  
Ronald W. Yeung
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Degree Of Freedom ◽  
Hydrodynamic Theory ◽  
Cost Ratio ◽  
Perfect Absorber ◽  
Control Force ◽  
Energy Converter ◽  
Power Absorption ◽  
Restraining Force

The aim of this paper is to maximize the power-to-load ratio of the Berkeley Wedge: a one-degree-of-freedom, asymmetrical, energy-capturing, floating breakwater of high performance that is relatively free of viscosity effects. Linear hydrodynamic theory was used to calculate bounds on the expected time-averaged power (TAP) and corresponding surge restraining force, pitch restraining torque, and power take-off (PTO) control force when assuming that the heave motion of the wave energy converter remains sinusoidal. This particular device was documented to be an almost-perfect absorber if one-degree-of-freedom motion is maintained. The success of such or similar future wave energy converter technologies would require the development of control strategies that can adapt device performance to maximize energy generation in operational conditions while mitigating hydrodynamic loads in extreme waves to reduce the structural mass and overall cost. This paper formulates the optimal control problem to incorporate metrics that provide a measure of the surge restraining force, pitch restraining torque, and PTO control force. The optimizer must now handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads. A penalty weight is placed on the surge restraining force, pitch restraining torque, and PTO actuation force, thereby allowing the control focus to be placed either on power absorption or load mitigation. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results in the form of TAP, reactive TAP, and the amplitudes of the surge restraining force, pitch restraining torque, and PTO control force are shown for the Berkeley Wedge example.

scholarly journals Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter

2016 ◽  
Author(s):  
Nathan M. Tom ◽  
Yi-Hsiang Yu ◽  
Alan D. Wright ◽  
Michael Lawson
Keyword(s):  
Wave Energy ◽  
Reactive Power ◽  
Load Ratio ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
The Novel ◽  
Energy Converter ◽  
Power Requirement ◽  
Power Absorption ◽  
Structural Loading

The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

scholarly journals Total wave power absorption by a multi-float wave energy converter and a semi-submersible wind platform with a fast far field model for arrays

2021 ◽  
Author(s):  
Peter Stansby ◽  
Efrain Carpintero Moreno ◽  
Sam Draycott ◽  
Tim Stallard
Keyword(s):  
Wind Turbine ◽  
Wave Energy ◽  
Radiation Damping ◽  
Wave Energy Converter ◽  
Wave Power ◽  
Far Field ◽  
Energy Converter ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Total Wave

AbstractWave energy converters absorb wave power by mechanical damping for conversion into electricity and multi-float systems may have high capture widths. The kinetic energy of the floats causes waves to be radiated, generating radiation damping. The total wave power absorbed is thus due to mechanical and radiation damping. A floating offshore wind turbine platform also responds dynamically and damping plates are generally employed on semi-submersible configurations to reduce motion, generating substantial drag which absorbs additional wave power. Total wave power absorption is analysed here by linear wave diffraction–radiation–drag models for a multi-float wave energy converter and an idealised wind turbine platform, with response and mechanical power in the wave energy case compared with wave basin experiments, including some directional spread wave cases, and accelerations compared in the wind platform case. The total power absorption defined by capture width is input into a far field array model with directional wave spreading. Wave power transmission due a typical wind turbine array is only reduced slightly (less than 5% for a 10 × 10 platform array) but may be reduced significantly by rows of wave energy converters (by up to about 50%).

scholarly journals Shallow water effects on wave energy converters with hydraulic power take-off system

2016 ◽  
Vol 7 (3) ◽  
pp. 108-117 ◽  
Author(s):  
Ashank Sinha ◽  
D Karmakar ◽  
C Guedes Soares
Keyword(s):  
Water Depth ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Hydraulic Power ◽  
Power Absorption ◽  
Point Absorber ◽  
Effect Of Water ◽  
Wave Energy Converters ◽  
Energy Converters

The effect of water depth on the power absorption by a single heaving point absorber wave energy converter, attached to a hydraulic power take-off system, is simulated and analysed. The wave energy flux for changing water depths is presented and the study is carried out at a location in the north-west Portuguese coast, favourable for wave power generation. This analysis is based on a procedure to modify the wave spectrum as the water depth reduces, namely, the TMA spectrum (Transformation spectrum). The present study deals with the effect of water depth on the spectral shape and significant wave heights. The reactive control strategy, which includes an external damping coefficient and a negative spring term, is used to maximize power absorption by the wave energy converter. The presented work can be used for making decisions regarding the best water depth for the installation of point absorber wave energy converters in the Portuguese nearshore.

Sign in / Sign up

Export Citation Format

Share Document