Seismic Design for Offshore Wind Farms – Lessons Learnt From the ACE Joint Industry Project

2021 ◽  
Author(s):  
Marcus Klose ◽  
Junkan Wang ◽  
Albert Ku
Keyword(s):  
Seismic Design ◽  
Wind Turbines ◽  
Wind Farms ◽  
The United States ◽  
Offshore Wind ◽  
Seismic Load ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
Asian Pacific Region ◽  
The Impact

Abstract In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that the impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local as well as international offshore oil & gas standards do not consider the specifics of modern wind turbines. In 2019, DNV GL started a Joint Industry Project (JIP) called “ACE -Alleviating Cyclone and Earthquake challenges for wind farms”. Based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed. It will supplement existing standards like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. This paper addresses the area of seismic load calculation and the details of combining earthquake impact with other environmental loads. Different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented. Seismic ground motions using a uniform profile or depth-varying input profile are discussed. Finally, the seismic load design return period is addressed.

scholarly journals Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1995
Author(s):  
Alexandre Mathern ◽  
Christoph von der Haar ◽  
Steffen Marx
Keyword(s):  
Wind Turbines ◽  
Wind Farms ◽  
Steel Structures ◽  
Production Costs ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Future Trends ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
New Developments

Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.

Floating Offshore Wind Turbines

2008 ◽  
Vol 42 (2) ◽  
pp. 39-43 ◽  
Author(s):  
Paul Sclavounos
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Research Effort ◽  
Wind Farms ◽  
Offshore Wind ◽  
Response Dynamics ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
The Impact

Wind is a rapidly growing renewable energy source, increasing at an annual rate of 30%, with the vast majority of wind power generated from onshore wind farms. The growth of these facilities, however, is limited by the lack of inexpensive land near major population centers and the visual impact caused by large wind turbines.Wind energy generated from floating offshore wind farms is the next frontier. Vast sea areas with stronger and steadier winds are available for wind farm development and 5 MW wind turbine towers located 20 miles from the coastline are invisible. Current offshore wind turbines are supported by monopoles driven into the seafloor or other bottom mounted structures at coastal sites a few miles from shore and in water depths of 10-15 m. The primary impediment to their growth is their prohibitive cost as the water depth increases.This article discusses the technologies and the economics associated with the development of motion resistant floating offshore wind turbines drawing upon a seven-year research effort at MIT. Two families of floater concepts are discussed, inspired by developments in the oil and gas industry for the deep water exploration of hydrocarbon reservoirs. The interaction of the floater response dynamics in severe weather with that of the wind turbine system is addressed and the impact of this coupling on the design of the new generation of multi-megawatt wind turbines for offshore deployment is discussed. The primary economic drivers affecting the development of utility scale floating offshore wind farms are also addressed.

scholarly journals Simplified Formulae for the Estimation of Offshore Wind Turbines Clutter on Marine Radars

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Olatz Grande ◽  
Josune Cañizo ◽  
Itziar Angulo ◽  
David Jenn ◽  
Laith R. Danoon ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Impact Analysis ◽  
System Modeling ◽  
Wind Farms ◽  
Software Tools ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Modeling Software ◽  
The Impact

The potential impact that offshore wind farms may cause on nearby marine radars should be considered before the wind farm is installed. Strong radar echoes from the turbines may degrade radars’ detection capability in the area around the wind farm. Although conventional computational methods provide accurate results of scattering by wind turbines, they are not directly implementable in software tools that can be used to conduct the impact studies. This paper proposes a simple model to assess the clutter that wind turbines may generate on marine radars. This method can be easily implemented in the system modeling software tools for the impact analysis of a wind farm in a real scenario.

The spreading of suspended matter formed during construction works of offshore wind farms

2020 ◽  
Author(s):  
Anna Przyborska ◽  
Maciej Muzyka ◽  
Jan Andrzejewski ◽  
Jaromir Jakacki ◽  
Daniel Rak
Keyword(s):  
Numerical Model ◽  
Wind Turbines ◽  
Suspended Matter ◽  
Turbulent Viscosity ◽  
Weather Prediction ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The Impact ◽  
Construction Works

<p>Offshore Wind Farms play a significant role in ensuring Europe's energy security. In Poland, a significant increase in the  number  of  newly-constructed  wind turbines  has  been  observed  in  recent  years. Wind power is "clean", but not completely free of environmental impacts. Their impact on the environment is difficult to assess. The impact of dredging works on suspended matter created during construction works will be presented  based on numerical model results. A model has been built based on MIKE, tools supplied by the Danish Hydraulic Institute (DHI) and the Weather Research and Forecasting model (WRF)- mesoscale numerical weather prediction system. Based on the numerical model created, analysis of the temporal and spatial variability of the spreading suspension generated from dredging works carried out during construction works aimed at positioning the wind turbines in appropriate places.</p><p>The advective-diffusive character of transported matter is the most natural clean, their direction, turbulent viscosity and sedimentation rate. Authors evaluated that during the construction phase, concentration of the suspended sediment will exceed 10 mg/l, which is denerous value for cod larvae, for short time (no longer than 48 hours) and will cover small area. The deposition will be irrelevant, the largest rate will occur in the immediate vicinity of the construction works and it will decrease with the distance. The range of the transferable suspension will not exceed 15 km. Cumulative factors significantly increase the concentration of the suspension (in a critical case they may even double it). They may occur when simultaneous actions are taken to prepare the foundation for more than one wind turbine at the same time, which is rather technical impossible because there is not a lot of special purpose sea vessel that are able to work on construction of basements of the offshore wind generators.</p><p> </p>

An ecosystem approach for studying the impact of offshore wind farms: a French case study

2018 ◽  
Vol 77 (3) ◽  
pp. 1238-1246 ◽  
Author(s):  
Jean-Philippe Pezy ◽  
Aurore Raoux ◽  
Jean-Claude Dauvin
Keyword(s):  
Network Analysis ◽  
Wind Farm ◽  
Wind Farms ◽  
Sampling Strategy ◽  
Ecosystem Approach ◽  
Offshore Wind ◽  
Ecosystem Structure ◽  
Offshore Wind Farms ◽  
Ecopath Model ◽  
The Impact

Abstract The French government is planning the construction of offshore wind farms (OWF) in the next decade (around 2900 MW). Following the European Environmental Impact Assessment Directive 85/337/EEC, several studies have been undertaken to identify the environmental conditions and ecosystem functioning at selected sites prior to OWF construction. However, these studies are generally focused on the conservation of some species and there is no holistic approach for analysing the effects arising from OWF construction and operation. The objective of this article is to promote a sampling strategy to collect data on the different ecosystem compartments of the future Dieppe-Le Tréport (DLT) wind farm site, adopting an ecosystem approach, which could be applied to other OWFs for the implementation of a trophic network analysis. For that purpose, an Ecopath model is used here to derive indices from Ecological Network Analysis (ENA) to investigate the ecosystem structure and functioning. The results show that the ecosystem is most likely detritus-based, associated with a biomass dominated by bivalves, which could act as a dead end for a classic trophic food web since their consumption by top predators is low in comparison to their biomass. The systemic approach developed for DLT OWF site should be applied for other French and European installations of Offshore Wind Farm.

Offshore Wind Energy and the Mid-Atlantic Cold Pool: A Review of Potential Interactions

2021 ◽  
Vol 55 (4) ◽  
pp. 72-87
Author(s):  
Travis Miles ◽  
Sarah Murphy ◽  
Josh Kohut ◽  
Sarah Borsetti ◽  
Daphne Munroe
Keyword(s):  
Wind Energy ◽  
Wind Farm ◽  
Vertical Mixing ◽  
Wind Farms ◽  
The United States ◽  
Offshore Wind ◽  
Cold Pool ◽  
Ocean Bottom ◽  
Offshore Wind Farms ◽  
Seasonal Thermocline

Abstract The U.S. East Coast has 1.7 million acres of federal bottom under lease for the development of wind energy installations, with plans for more than 1,500 foundations to be placed. The scale of these wind farms has the potential to alter the unique and delicate oceanographic conditions along the expansive Atlantic continental shelf, a region characterized by a strong seasonal thermocline that overlies cold bottom water, known as the “Cold Pool.” Strong seasonal stratification traps cold (typically less than 10°C) water above the ocean bottom sustaining a boreal fauna that represents vast fisheries, including the most lucrative shellfish fisheries in the United States. This paper reviews the existing literature and research pertaining to the ways in which offshore wind farms may alter processes that establish, maintain, and degrade stratification associated with the Cold Pool through vertical mixing in this seasonally dynamic system. Changes in stratification could have important consequences in Cold Pool setup and degradation, processes fundamental to high fishery productivity of the region. The potential for these multiple wind energy arrays to alter oceanographic processes and the biological systems that rely on them is possible; however, a great deal of uncertainty remains about the nature and scale of these interactions. Research should be prioritized that identifies stratification thresholds of influence, below which turbines and wind farm arrays may alter oceanographic processes. These should be examined within context of spatial and seasonal dynamics of the Cold Pool and offshore wind lease areas to identify potential areas of further study.

scholarly journals Impact of Primary Frequency Control of Offshore HVDC Grids on Interarea Modes of Power Systems

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3879 ◽  
Author(s):  
Ali Bidadfar ◽  
Oscar Saborío-Romano ◽  
Vladislav Akhmatov ◽  
Nicolaos A. Cutululis ◽  
Poul E. Sørensen
Keyword(s):  
Power Systems ◽  
Frequency Control ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Dc Voltage ◽  
Simultaneous Use ◽  
Primary Frequency ◽  
Primary Frequency Control ◽  
The Impact

Offshore high-voltage DC (HVDC) grids are developing as a technically reliable and economical solution to transfer more offshore wind power to onshore power systems. It is also foreseen that the offshore HVDC grids pave the way for offshore wind participation in power systems’ balancing process through frequency support. The primary frequency control mechanism in an HVDC grid can be either centralized using communication links between HVDC terminals or decentralized by the simultaneous use of DC voltage and frequency droop controls. This paper investigates the impact of both types of primary frequency control of offshore HVDC grids on onshore power system dynamics. Parametric presentation of power systems’ electro-mechanical dynamics and HVDC controls is developed to analytically prove that the primary frequency control can improve the damping of interarea modes of onshore power systems. The key findings of the paper include showing that the simultaneous use of frequency and DC voltage droop controls on onshore converters results in an autonomous share of damping torque between onshore power systems even without any participation of offshore wind farms in the frequency control. It is also found that the resulting damping from the frequency control of offshore HVDC is not always reliable as it can be nullified by the power limits of HVDC converters or wind farms. Therefore, using power oscillation damping control in parallel with frequency control is suggested. The analytical findings are verified by simulations on a three-terminal offshore HVDC grid.

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