Power production of the hybrid Wavestar point absorber mounted around the Hywind spar platform and its dynamic response

2021 ◽  
Vol 13 (3) ◽  
pp. 033308
Author(s):  
Hamid Reza Ghafari ◽  
Atefeh Neisi ◽  
Hassan Ghassemi ◽  
Mehdi Iranmanesh
Keyword(s):  
Dynamic Response ◽  
Power Production ◽  
Spar Platform ◽  
Point Absorber

Effects of Misaligned Wave and Wind Action on the Response of the Combined Concept WindWEC

2018 ◽  
Author(s):  
Madjid Karimirad ◽  
Constantine Michailides
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wave Energy ◽  
Power Production ◽  
Energy System ◽  
Mooring Line ◽  
Offshore Platforms ◽  
Dynamic Simulations ◽  
Line System ◽  
Wind Action

In the present paper, the effects of misaligned wave and wind action on the dynamic response of the WindWEC combined concept are evaluated and presented. WindWEC is a recently proposed combined wind and wave energy system; a hybrid offshore energy system that consists of: (a) a 5MW floating wind turbine supported by a spar-type substructure (e.g. Hywind), a Wave Energy Converter (WEC) that is of heaving buoy type (e.g. Wavestar), (c) a structural arm that connects the spar with the WEC and (d) a common mooring system. Hybrid offshore platforms are combining wave and wind energy systems and are designed in order to gain the possible synergy effects and reduce the cost of generated electrical power while increasing the quality of delivered power to grids. During the lifetime of a combined concept, wave and wind can be misaligned which may affect the dynamic response and as a result the functionality of it. In particular, for asymmetric configurations, the misalignment of the wave and wind may result in unexpected behaviour and significant effects that may reduce the produced power. For the case of the WindWEC concept, the relative motion of the spar platform and WEC buoy results to the produced power. In this paper, the dynamic response and power production of the buoy type WEC and wind turbine are examined for different loading conditions where the wave and wind are misaligned. Integrated/coupled aero-hydro-servo-elastic time-domain dynamic simulations considering multi-body analyses are applied. The motion, structural and tension responses as well as power production are examined. The misalignment of wave and wind results to higher loads that affect the mooring line system and motion responses of the spar. It is found that the produced power of wind turbine is not significantly affected.

Experimental Study on Model Predictive Control for a Point Absorber Type Wave Energy Converter With a Linear Generator

2018 ◽  
Author(s):  
Jun Umeda ◽  
Hiroki Goto ◽  
Toshifumi Fujiwara ◽  
Tomoki Taniguchi ◽  
Shunji Inoue
Keyword(s):  
Predictive Control ◽  
Wave Energy ◽  
Spectral Distribution ◽  
Time Horizon ◽  
Production Efficiency ◽  
Power Production ◽  
Irregular Waves ◽  
Regular Waves ◽  
Energy Converter ◽  
Point Absorber

This paper presents the experimental evaluation results of power production efficiency of model predictive control (MPC) on a wave energy converter (WEC) with a linear generator in regular and irregular waves. A bottom-fixed WEC of point absorber type was subjected to the WEC model in this paper. To compare the power production efficiency, the power production efficiency of the approximate complex-conjugate control with considering the copper loss (ACL) was also evaluated. In regular waves, the MPC performance was comparable to the ACL one in the power-production amount reasonably. In irregular waves which have narrow band spectral distribution, a same trend as the trend in regular waves was obtained. On the other hand, in irregular waves which have broadband spectral distribution, the MPC was more effective than the ACL. Moreover, Experiments in regular and irregular waves were carried out in the MPC under the constraint of the small heave displacement. The constraint of the displacement was approximately satisfied by the MPC. This is useful in practical operation. It is also investigated experimentally how time horizon affects the performance of the MPC. When the time horizon is short, the power production amount of the MPC increases.

scholarly journals Dynamic response and power production of a floating integrated wind, wave and tidal energy system

2018 ◽  
Vol 116 ◽  
pp. 412-422 ◽  
Author(s):  
Liang Li ◽  
Yan Gao ◽  
Zhiming Yuan ◽  
Sandy Day ◽  
Zhiqiang Hu
Keyword(s):  
Dynamic Response ◽  
Wind Wave ◽  
Tidal Energy ◽  
Power Production ◽  
Energy System

Dynamic Response Analysis of a Spar Platform Subjected to Wind and Wave Forces

2008 ◽  
Author(s):  
Bernt J. Leira ◽  
Dag Myrhaug ◽  
Jarle Voll
Keyword(s):  
Dynamic Response ◽  
Roughness Parameter ◽  
Response Analysis ◽  
Wave Forces ◽  
Wind Gust ◽  
Wave Age ◽  
Spar Platform ◽  
Dynamic Response Analysis ◽  
Wind Speeds ◽  
Wind Response

Results from a study on dynamic response analysis of a floating production unit (FPSO) excited by wave and wind forces are presented. The FPSO is examplified by a Spar platform considering the motion in surge and pitch. The wind gust is modelled with the Harris [4] and Ochi and Shin [7] wind gust spectra. The effect of the wave age on the wind gust spectrum is included by adopting the Volkov wave age dependent sea surface roughness parameter [10]; the wave age independent Charnock roughness parameter [2] is also used as a reference. Examples of results demonstrate clear effects of wave age on the dynamic response. Moreover, for high mean wind speeds the total wind response is much smaller than the wave response, but for low mean wind speeds the wind appears to be more important.

scholarly journals Effects of Mooring Compliancy on the Mooring Forces, Power Production, and Dynamics of a Floating Wave Activated Body Energy Converter

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3535 ◽  
Author(s):  
Luca Martinelli ◽  
Barbara Zanuttigh
Keyword(s):  
Power Production ◽  
Mooring System ◽  
Wave Direction ◽  
Energy Converter ◽  
Energy Device ◽  
Mooring Lines ◽  
Point Absorber ◽  
Deep Waters ◽  
Mooring Forces ◽  
Body Energy

The paper aims at investigating the interactions between a floating wave energy device (WEC) and its mooring system under a variety of wave conditions (regular and irregular, perpendicular and oblique, ordinary and extreme). The analyzed WEC is the DEXA, a wave activated body point absorber, of the type that performs better when aligned to the incident wave direction. Two typologies of mooring systems were studied: for limited depths, the spread system, with a disposition of the lines that do not constrain the yaw movements; for large depths, the catenary anchor leg mooring (CALM) system. The spread system was experimentally investigated, including a realistic power take-off system, to capture non-linear behaviors and assess device motions, power production, and forces on mooring lines. The CALM system was numerically simulated, as mooring modelling is more reliable in deep waters and allows testing of a number of different configurations, by changing the number of the mooring lines and the mooring layout. The experiments showed that a reduction of the mooring compliancy increases the power production. The numerical simulations showed that a redundancy on the number of chains allows a better distribution of the loads, with advantages on reliability and costs.

Research on the Influence of Helical Strakes and Its Parameters on Dynamic Response of Platform of Floating Wind Turbine Based on Optimization Method of Orthogonal Design

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Qinwei Ding ◽  
Chun Li ◽  
Binxin Li ◽  
Wenxing Hao ◽  
Zhou Ye
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Orthogonal Design ◽  
Exciting Force ◽  
Design Parameters ◽  
Spar Platform ◽  
Floating Wind Turbine ◽  
Helical Strakes ◽  
Pitch Ratio ◽  
The Impact

The stability of platform is the most fundamental guarantee for the safe operation of floating wind turbine in complex marine environment. The helical strakes used on spar platform in the traditional oil industry are useful and effective. This paper is to investigative the validity of helical strakes when used for offshore wind energy harvesting. The National Renewable Energy Laboratory (NREL) 5 MW wind turbine based on OC3-Hywind spar-buoy platform with the attachment of helical strakes is modeled for the purpose to analysis the impact of helical strakes and its design parameters (number, height, and pitch ratio) on the dynamic response of the floating wind turbine spar platform. The dynamic response of spar platform under wind, wave, and current loads is calculated and analyzed based on the radiation and diffraction theory, the finite element method, and the orthogonal design method. The research result shows that the helical strakes can effectively suppress the dynamic response of the platform but enlarge the wave exciting force, and helical strakes cannot change peak frequency of response amplitude operator (RAO) and wave exciting force of spar in frequency-domain. The best parameter combination is two pieces of helical strakes with height of 15%D and the pitch ratio of 5. Height and pitch ratio of the helical strakes have significant influence on pitch response, while the number and interaction of height and pitch ratio have slight effect.

scholarly journals A Novel 2-D Point Absorber Numerical Modelling Method

Inventions ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 75
Author(s):  
Gianmaria Giannini ◽  
Sandy Day ◽  
Paulo Rosa-Santos ◽  
Francisco Taveira-Pinto
Keyword(s):  
Numerical Modelling ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Cost Effective ◽  
The Novel ◽  
Wave Loads ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Point Absorbers ◽  
The Time Domain

Despite several wave energy converters (WECs) having been developed to present, no particular concept has emerged yet. The existing inventions vary significantly in terms of the operation principle and complexity of WECs. The tethered point absorbers (PAs) are among the most known devices that, thanks to their simplicity, appear to be cost-effective and reliable for offshore installation. These devices need to be advanced further and, therefore, new tailored modelling methods are required. Numerical modelling of this type of WEC has been done mainly in one degree of freedom. Existing methods for multi-degrees of freedom analysis lack pragmatism and accuracy. Nevertheless, modelling of multiple degrees of freedom is necessary for correct analysis of the device dynamic response, wave loads and device performance. Therefore, an innovative numerical method for two degrees of freedom analysis of PA WECs, which permits precisely modelling the dynamics of PA for surge and heave motions, is introduced in this paper. The new method allows assessing, in the time-domain, the dynamic response of tethered PAs using regular and irregular sea states. The novel numerical model is explained, proved and empirically validated.

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