EXCITATION AND DYNAMIC RESPONSES OF JACKET STRUCTURES IN REGULAR WAVES FOR OFFSHORE INSTALLATION

The worldâ€™s energy supply needs to scope two aims: Securing an ongoing growth in energy demand while gradually shifting to exploitation of renewable energy resources. Since onshore and near shore areas to harvest energy from wind are running short, the focus is laid on concepts for deep water regions ranging from 30 up to 50m with over 6MW. The presented work is a part of the research project HyConCast which progresses the development of a novel, hybrid support structure for offshore wind turbines. Thereby the concept addresses to develop and deploy hybrid offshore wind farm support structures which are based on the advantages of combined ductile iron casting knots and precast concrete pipes. The overall objective of the project is to assess the feasibility and general applicability under design load cases stemming from environmental, eco-logical and economical dimensions. With respect to the distinctly higher total weight of the hybrid structure compared to common steal structures, the results of its so far not understood excitation and dynamic motion response in regular waves during floating installation are researched and discussed in the following article.

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Study on the Dynamic Response for Floating Foundation of Offshore Wind Turbine

Volume 5: Ocean Space Utilization; Ocean Renewable Energy ◽

10.1115/omae2011-50329 ◽

2011 ◽

Author(s):

Yougang Tang ◽

Jun Hu ◽

Liqin Liu

Keyword(s):

Wind Turbine ◽

Wind Farm ◽

Dynamic Responses ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Wave Load ◽

Mooring Lines ◽

Floating Foundation ◽

Wind Turbine System ◽

Sea Area

The wind resources for ocean power generation are mostly distributed in sea areas with the distance of 5–50km from coastline, whose water depth are generally over 20m. To improve ocean power output and economic benefit of offshore wind farm, it is necessary to choose floating foundation for offshore wind turbine. According to the basic data of a 600kW wind turbine with a horizontal shaft, the tower, semi-submersible foundation and mooring system are designed in the 60-meter-deep sea area. Precise finite element models of the floating wind turbine system are established, including mooring lines, floating foundation, tower and wind turbine. Dynamic responses for the floating foundation of offshore wind turbine are investigated under wave load in frequency domain.

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Efficient Pile Design for Offshore Wind Farm Jacket Structures

Offshore Site Investigation Geotechnics 8th International Conference Proceedings ◽

10.3723/osig17.1070 ◽

2017 ◽

pp. 1070-1077

Author(s):

S Manceau ◽

A Benson

Keyword(s):

Wind Farm ◽

Offshore Wind ◽

Offshore Wind Farm ◽

Pile Design ◽

Jacket Structures

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Semi-Submersible Gravity Based Hybrid Structure: An Alternative to Jacket and Topside Platforms

Volume 8B: Ocean Engineering ◽

10.1115/omae2014-23954 ◽

2014 ◽

Author(s):

Peter Sjögren ◽

Björn Fagerström ◽

Monica Bellgran ◽

Peter Sandeberg

Keyword(s):

Wind Farm ◽

Hybrid Structure ◽

Offshore Platform ◽

Offshore Wind ◽

Cost Overruns ◽

Direct Observations ◽

Specialized Equipment ◽

Pros And Cons ◽

Safety And Environment

The aim of this research is to present the result from a case study comparing a semi-submersible gravity based hybrid structure and a jacket topside structure for two offshore wind farm converter station projects. The cases are analyzed from a transportation and installation perspective. Converter stations enable the conversion from alternating to direct current, more efficiently bringing generated wind energy to shore. Out of the project process phases e.g. planning, engineering, fabrication, transport, installation and commissioning; transportation and installation are two of the most demanding during offshore platform projects. The weight and size of an offshore platform require specialized equipment, vessels and marine contractors’ expertise to be transported and installed. The risks associated with transportation and installation (T&I) operations are related to health, safety and environment, and T&I operations are also sensitive to any disturbance e.g. accidents and delays. Many interdependencies between disciplines in the project execution process may result in consequential and immediate impact, should an activity not follow the plan and thus the risk of cost overruns increases. In an attempt to circumvent risks related to heavy lifts offshore and consequently mitigate the corresponding risks, a new platform concept has been developed a Norwegian EPC–company and a Swiss converter station manufacturer, a semi-submersible gravity based hybrid, SSGBH. The subjects presented in this paper include the general principles of the SSGBH concept and in what way risk associated with T&I operations are reduced. This paper present the platform concepts, data gathered from interviews, archival data and direct observations. Their pros and cons are presented in an objective way, while concluding that platform concepts of this kind are and should be highly customized, as should the concept selection.

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Characteristics of the Wave Slamming Forces on Jacket Structures Under Plunging Breaking Waves Based on Experimental Data

Volume 7B: Ocean Engineering ◽

10.1115/omae2017-61789 ◽

2017 ◽

Cited By ~ 1

Author(s):

Jithin Jose ◽

Olga Podrażka ◽

Ove Tobias Gudmestad ◽

Witold Cieślikiewicz

Keyword(s):

Energy Demand ◽

Clean Energy ◽

Breaking Waves ◽

Offshore Structures ◽

Offshore Wind ◽

Wave Forces ◽

Breaking Wave ◽

Jacket Structures ◽

Wave Slamming ◽

Wave Properties

Due to increased energy demand and thrive for clean energy, offshore wind energy has become popular these days. A large number of offshore wind turbines supported by fixed type substructures have been installed, among which jacket structures are getting popular in recent times. The forces from breaking waves are a major concern in the design of offshore structures installed in shallow waters. However, there are only limited studies available regarding breaking wave forces on jacket structures and still there exist many uncertainties in this area. During the WaveSlam experiment carried out in 2013, a jacket structure of 1:8 scale was tested on a large number of breaking wave conditions. Wave properties and the forces on the structure were measured during the experiment. The total wave slamming forces are being filtered from the experimental measured force using the Empirical Mode Decomposition method and local slamming forces are obtained by the Frequency Response Function method. Based on these results, the peak slamming force and slamming coefficients on the jacket members are estimated. The wave parameters (wave height and period) and wave front asymmetry are obtained from measured wave properties. The variation of slamming forces and slamming coefficients with respect to these parameters are also investigated.

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Short-Term Wind Characteristics Forecasting Using Stacked LSTM Networks

10.1115/power2021-65866 ◽

2021 ◽

Author(s):

Dorsa Ziaei ◽

Navid Goudarzi

Keyword(s):

Energy Demand ◽

Wind Farm ◽

Short Term Memory ◽

Vital Role ◽

Offshore Wind ◽

Training Dataset ◽

Short Term ◽

Offshore Wind Turbines ◽

Wind Forecasting ◽

Wind Characteristics

Abstract Onshore/offshore wind turbines play a vital role in addressing the increasing worldwide energy demand. Enhancing the wind power harnessing capability of turbines and extending the life expectancy of their components support further reductions in the final cost of wind energy. Data-driven techniques can complement existing physics-based approaches for complex problems such as wind farm wake modeling. In this paper, a deep learning model is developed to predict the local short-term wind characteristics. A data pre-processing pipeline that includes data cleaning and normalizing steps is developed to generate the training dataset. Time-series forecasting models based on long-short-term-memory (LSTM) and convLSTM are developed and trained for local short-term wind forecasting. The model is validated through experiments on three-year data from the National Renewable Energy Laboratory (NREL) database. The conducted experiments showed favorable performance based on root mean square error (RMSE) and R2 test scores. The R2 values for predicting 1-minute, 30-minute, and 1 hour, wind characteristics for both LSTM and convLSTM were above 0.92. The results are in agreement with the literature. They also demonstrate the effectiveness of the developed models for short-term wind forecasting compared to similar ones.

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Experimental Analysis on Dynamic Responses of an Electrical Platform for an Offshore Wind Farm under Earthquake Load

Journal of Marine Science and Engineering ◽

10.3390/jmse7080279 ◽

2019 ◽

Vol 7 (8) ◽

pp. 279 ◽

Cited By ~ 2

Author(s):

Zhen-Zhou Sun ◽

Chun-Wei Bi ◽

Sheng-Xiao Zhao ◽

Guo-Hai Dong ◽

Hua-Feng Yu

Keyword(s):

Wind Farm ◽

Damping Ratio ◽

Dynamic Effect ◽

Dynamic Responses ◽

Offshore Wind ◽

Seismic Excitation ◽

Physical Model Test ◽

Seismic Load ◽

Seismic Action ◽

Offshore Wind Farm

Offshore wind power is gradually developing to more open sea. Considering the economy of power transmission, it will be an inevitable choice to adopt the extra-large electrical platform. The offshore electrical platform is easily affected by sudden extreme loads such as earthquake and high current loads. With a large volume of electrical equipment arranged on the deck, the offshore electrical platform is characterized as a top-heavy structure in the offshore wind farm. The dynamic effect of the structure will aggravate the vibration problem of the structure. In this paper, a physical model test was carried out to study the dynamic characteristics of the electrical platform of a 10,000-ton offshore converter station under seismic load. The acceleration response, displacement response and stress response of the offshore electrical platform under the typical direction of seismic action were obtained. The effect of the dry–wet environment, mode of seismic excitation, whipping effect and weak positions of electrical platform structure were analyzed. It was determined that the average damping ratio of the first-order mode of the electrical platform was 5.73% and 8.68% with and without water, respectively. The bidirectional seismic excitation was more dangerous to the structure than unidirectional excitation. The peak acceleration along the height of the platform showed a typical whipping effect.

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Evaluation of the wind power potential in the European nearshore of the Mediterranean Sea

E3S Web of Conferences ◽

10.1051/e3sconf/201910301003 ◽

2019 ◽

Vol 103 ◽

pp. 01003

Author(s):

Eugen Rusu ◽

Liliana Rusu

Keyword(s):

Mediterranean Sea ◽

Wind Power ◽

Energy Demand ◽

Climate Model ◽

Energy Resource ◽

High Energy ◽

Offshore Wind ◽

Climate Projections ◽

Renewable Energy Resources ◽

The Mediterranean

In the last years, the offshore wind sector has been constantly growing in Europe, coming also with a very competitive production price. The objective of this paper is to evaluate the wind power potential in the European coastal environment of the Mediterranean Sea, an area with a high population density. Furthermore, a high energy demand exists here and the potential of the renewable energy resources needs to be assessed for further exploitation. The analysis was performed considering some reference locations. The climate change impact on the wind energy resource is also investigated. Various comparisons between historical data and future climate projections simulated by a Regional Climate Model under RCP4.5 scenario are made. The results obtained show that in various locations, especially in Golf of Lion and the Aegean Sea, there are appropriate conditions for offshore wind exploitations.

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Investigating the Influence of MCP Uncertainties on the Energy Storage Capacity Requirements for Offshore Windfarms

ASME 2019 2nd International Offshore Wind Technical Conference ◽

10.1115/iowtc2019-7504 ◽

2019 ◽

Author(s):

Michael D. Mifsud ◽

Robert N. Farrugia ◽

Tonio Sant

Keyword(s):

Time Series ◽

Energy Storage ◽

Wind Speed ◽

Wind Energy ◽

Power Output ◽

Energy Demand ◽

Wind Farm ◽

High Energy ◽

Offshore Wind ◽

Wind Data

Abstract Recent studies have shown that the intermittency of wind energy can be mitigated by means of an energy storage system (ESS). Energy can be stored during periods of low energy demand and high wind availability to then be utilised during periods of high energy demand. Measure-Correlate-Predict (MCP) methodologies are used to predict the wind speed and direction at a wind farm candidate site, hence enabling the estimation of the power output from the wind farm. Once energy storage is integrated with the wind farm, it is no longer only a matter of estimating the power output from the windfarm, but it is also important to model the behaviour of the ESS in conjunction with the energy demand. The latter is expected to depend, amongst other factors, on the reliability of the MCP methodology used. This paper investigates how different MCP methodologies influence the projected time series behaviour and the capacity requirements of ESS systems coupled to offshore wind farms. The analysis is based on wind data captured by a LiDAR system installed at a coastal location and from the Meteorological Office at Malta International Airport in the Maltese Islands. Different MCP methodologies are used to generate wind speed and direction time series at a candidate offshore wind farm site for various array layouts. The latter are then used in WindPRO® to estimate the time series power production for each MCP methodology and wind farm layout. This is repeated with actual wind data, such that the percentage error in energy yield from each MCP methodology is quantified, and the more reliable methodology could be identified. While it is evident that the integration of storage will reduce the need for wind energy curtailment, the reliability of the MCP methodology used is found to be crucial for proper estimation of the behaviour of the ESS.

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Multi-Terminal DC Grid with Wind Power Injection

Wind ◽

10.3390/wind2010002 ◽

2022 ◽

Vol 2 (1) ◽

pp. 17-36

Author(s):

Lilantha Samaranayake ◽

Carlos E. Ugalde-Loo ◽

Oluwole D. Adeuyi ◽

John Licari ◽

Janaka B. Ekanayake

Keyword(s):

Wind Farm ◽

Reactive Power ◽

Dynamic Responses ◽

Offshore Wind ◽

Voltage Source ◽

Voltage Source Converter ◽

Power Injection ◽

Power Frequency ◽

Cross Country ◽

Real Time Digital Simulator

With the development of offshore wind generation, the interest in cross-country connections is also increasing, which requires models to study their complex static and dynamic behaviors. This paper presents the mathematical modeling of an offshore wind farm integrated into a cross-country HVDC network forming a multi-terminal high-voltage DC (MTDC) network. The voltage source converter models were added with the control of active power, reactive power, frequency, and DC link voltages at appropriate nodes in the MTDC, resembling a typical cross-country multi-terminal type of HVDC scenario. The mathematical model for the network together with the controllers were simulated in MATLABTM and experimentally verified using a real-time digital simulator hardware setup. The resulting static and dynamic responses from the hardware setup agreed well with those from simulations of the developed models.

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