scholarly journals A Stochastic Petri Net Model for O&M Planning of Floating Offshore Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1134
Author(s):  
Tobi Elusakin ◽  
Mahmood Shafiee ◽  
Tosin Adedipe ◽  
Fateme Dinmohammadi
Keyword(s):  
Wind Energy ◽  
Wind Turbines ◽  
Wind Farms ◽  
Spare Parts ◽  
Offshore Wind ◽  
Floating Platform ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Proposed Model ◽  
Floating Offshore Wind Turbines

With increasing deployment of offshore wind farms further from shore and in deeper waters, the efficient and effective planning of operation and maintenance (O&M) activities has received considerable attention from wind energy developers and operators in recent years. The O&M planning of offshore wind farms is a complicated task, as it depends on many factors such as asset degradation rates, availability of resources required to perform maintenance tasks (e.g., transport vessels, service crew, spare parts, and special tools) as well as the uncertainties associated with weather and climate variability. A brief review of the literature shows that a lot of research has been conducted on optimizing the O&M schedules for fixed-bottom offshore wind turbines; however, the literature for O&M planning of floating wind farms is too limited. This paper presents a stochastic Petri network (SPN) model for O&M planning of floating offshore wind turbines (FOWTs) and their support structure components, including floating platform, moorings and anchoring system. The proposed model incorporates all interrelationships between different factors influencing O&M planning of FOWTs, including deterioration and renewal process of components within the system. Relevant data such as failure rate, mean-time-to-failure (MTTF), degradation rate, etc. are collected from the literature as well as wind energy industry databases, and then the model is tested on an NREL 5 MW reference wind turbine system mounted on an OC3-Hywind spar buoy floating platform. The results indicate that our proposed model can significantly contribute to the reduction of O&M costs in the floating offshore wind sector.

scholarly journals Numerical Study of a Proposed Semi-Submersible Floating Platform with Different Numbers of Offset Columns Based on the DeepCwind Prototype for Improving the Wave-Resistance Ability

2019 ◽  
Vol 9 (6) ◽  
pp. 1255
Author(s):  
Zhenqing Liu ◽  
Yicheng Fan ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbines ◽  
Numerical Study ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Decay Test ◽  
Floating Offshore Wind Turbines

DeepCwind semi-submersible floating offshore wind turbines have been widely examined, and in some countries this type of floating offshore wind turbine has been adopted in the construction of floating wind farms. However, the DeepCwind semi-submersible floating offshore wind turbines still experience large surge motion that limits their operational time. Therefore, in this study, a semi-submersible floating platform with different numbers of offset columns, but with the same total weight, based on the DeepCwind prototype is proposed. From the free-decay test, it was found that the number of the floating columns will affect the natural frequency of the platform. Furthermore, the regular wave test in the time domain and the irregular wave test in the frequency domain show that increasing the number of the floating columns will reduce the surge motion greatly, while the effects in the heave and pitch motions are not obvious.

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 Offshore Wind Energy Resource Assessment across the Territory of Oman: A Spatial-Temporal Data Analysis

2021 ◽  
Vol 13 (5) ◽  
pp. 2862
Author(s):  
Amer Al-Hinai ◽  
Yassine Charabi ◽  
Seyed H. Aghay Kaboli
Keyword(s):  
Data Analysis ◽  
Wind Energy ◽  
Wind Turbines ◽  
Energy Resource ◽  
Wind Farms ◽  
Offshore Wind ◽  
Wind Data ◽  
Offshore Wind Energy ◽  
Offshore Wind Turbines ◽  
Wind Potential

Despite the long shoreline of Oman, the wind energy industry is still confined to onshore due to the lack of knowledge about offshore wind potential. A spatial-temporal wind data analysis is performed in this research to find the locations in Oman’s territorial seas with the highest potential for offshore wind energy. Thus, wind data are statistically analyzed for assessing wind characteristics. Statistical analysis of wind data include the wind power density, and Weibull scale and shape factors. In addition, there is an estimation of the possible energy production and capacity factor by three commercial offshore wind turbines suitable for 80 up to a 110 m hub height. The findings show that offshore wind turbines can produce at least 1.34 times more energy than land-based and nearshore wind turbines. Additionally, offshore wind turbines generate more power in the Omani peak electricity demand during the summer. Thus, offshore wind turbines have great advantages over land-based wind turbines in Oman. Overall, this work provides guidance on the deployment and production of offshore wind energy in Oman. A thorough study using bankable wind data along with various logistical considerations would still be required to turn offshore wind potential into real wind farms in Oman.

Linear Stability Control of Offshore Wind Turbines

2010 ◽  
Author(s):  
Christine A. Mecklenborg ◽  
Philipp Rouenhoff ◽  
Dongmei Chen
Keyword(s):  
Wind Turbines ◽  
Deep Water ◽  
Fossil Fuels ◽  
Wind Farms ◽  
Stability Control ◽  
Offshore Wind ◽  
Wave Forces ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Strong Winds

Offshore wind farms in deep water are becoming an attractive prospect for harnessing renewable energy and reducing dependence on fossil fuels. One area of major concern with offshore wind turbines is stability control. The same strong winds that give deep water turbines great potential for energy capture also pose a threat to stability, along with potentially strong wave forces. We examine development of state space controllers for active stabilization of a spar-buoy floating turbine. We investigate linear state feedback with a state observer and evaluate response time and disturbance rejection of decoupled SISO controllers.

scholarly journals Development of offshore wind energy of Ukraine in the Sea of Azov: the geographical aspect

2021 ◽  
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbines ◽  
Wind Farms ◽  
Offshore Wind ◽  
Limiting Factors ◽  
Sea Of Azov ◽  
Energy Potential ◽  
Offshore Wind Farms ◽  
The Sea Of Azov

Formulation of the problem. Ukraine's energy sector is import-dependent, and one of the country’s sustainable development goals until 2030 is to ensure access to affordable, reliable, sustainable and modern energy sources. The wind potential of the mainland of our country has been thoroughly studied, so the focus of our interest is water areas, which are promising for the development of offshore wind energy. Offshore wind farms in Ukraine could improve the environmental situation and considerably contribute to the decarbonization of domestic energy. That is why the study considers the opportunity of offshore wind farms installation in the Sea of Azov. Methods. The analysis of literary and cartographic sources has been carried out. Mathematical methods have been used to calculate energy indicators. Using geoinformation modeling, taking into account limiting factors, suitable for the installation of offshore wind farms areas have been identified in the Sea of Azov. The purpose of the article is to geographically analyze the wind energy potential of the Sea of Azov with further assessment of the suitability of areas for the offshore wind farms location. Results. Our research has shown that the installation of offshore wind farms is appropriate in the Sea of Azov, because many areas are characterized by average annual wind speed above 6 meters per second. The most promising areas are the northern and northeastern coasts, where wind speed at different altitudes ranges from 8 to 9.3 meters per second. At altitudes of 50, 100 and 200 m, under the action of limiting factors, the most promising for offshore wind turbines areas are reduced by 8–22%. As considered limiting factors (territorial waters, nature protection objects, settlements and airports) have identical influence regardless of height, it is more effective to install wind turbines with a tower height of more than 100 m in the waters of the Sea of Azov. Interdisciplinary research is needed for the final answer on the effectiveness of offshore wind turbines in the Sea of Azov. Scientific novelty and practical significance. The results of the analysis of the wind energy potential of the Sea of Azov have been given, the tendency of its growth from the west to the east has been revealed. Attention has been paid to the method of geoinformation modeling of the location of offshore wind farms taking into account limiting factors. Maps of wind speed, potential of electricity generated by a single wind turbine and suitability of areas of the Sea of Azov for the location of offshore wind farms at an altitude of 200 m above sea level have been presented. These data can be used by designers of wind energy facilities as a basis for determining the optimal power of wind turbines and the type of energy for a particular area of the Sea of Azov.

Harmonizing the Mooring System Reliability of Multiline Anchor Wind Farms

2021 ◽  
Vol 7 (4) ◽  
Author(s):  
Spencer T. Hallowell ◽  
Sanjay R. Arwade ◽  
Brian D. Diaz ◽  
Charles P. Aubeny ◽  
Casey M. Fontana ◽  
...  
Keyword(s):  
Wind Turbines ◽  
System Reliability ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Line System ◽  
Offshore Wind Turbines ◽  
Anchor System ◽  
Floating Offshore Wind Turbines ◽  
Additional Safety

Abstract One of many barriers to the deployment of floating offshore wind turbines is the high cost of vessel time needed for soil investigations and anchor installation. A multiline anchor system is proposed in which multiple floating offshore wind turbines (FOWTs) are connected to a single caisson. The connection of multiple FOWTs to a single anchor introduces interconnectedness throughout the wind farm. Previous work by the authors has shown that this interconnectedness reduces the reliability of the FOWT below an acceptable level when exposed to survival loading conditions. To combat the reduction in system reliability an overstrength factor (OSF) is applied to the anchors functioning as an additional safety factor. For a 100 turbine wind farm, single-line system reliabilities can be achieved using the multiline system with an OSF of 1.10, a 10% increase in multiline anchor safety factors for all anchors in a farm.

Technology of Offshore Wind Turbines and Farms and Novel Multilevel Converter-Based HVDC Systems for Their Grid Connections

2002 ◽  
Vol 26 (6) ◽  
pp. 383-395 ◽  
Author(s):  
Vassilios G. Agelidis ◽  
Christos Mademlis
Keyword(s):  
Wind Turbines ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Hvdc System

The technology associated with offshore wind farms is discussed in detail. First, the various offshore wind turbines are reviewed and the factors influencing their characteristics are outlined in comparison with their onshore counterparts. This overview serves as a basis for the discussion that follows regarding the possible electrical connection within the farm, and between the farm and the grid. Voltage-source converter-based HV DC connection is compared with HVAC connection. Finally, a novel multilevel converter-based HVDC system, based on flying capacitor multilevel converters is proposed, as a possible interface between the farm and the grid.

scholarly journals Seismic Design of Offshore Wind Turbines: Good, Bad and Unknowns

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3496
Author(s):  
Subhamoy Bhattacharya ◽  
Suryakanta Biswal ◽  
Muhammed Aleem ◽  
Sadra Amani ◽  
Athul Prabhakaran ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Wind Farms ◽  
Offshore Wind ◽  
Future Research ◽  
Offshore Wind Farms ◽  
Analysis And Design ◽  
Offshore Wind Turbines ◽  
Floating Systems

Large scale offshore wind farms are relatively new infrastructures and are being deployed in regions prone to earthquakes. Offshore wind farms comprise of both offshore wind turbines (OWTs) and balance of plants (BOP) facilities, such as inter-array and export cables, grid connection etc. An OWT structure can be either grounded systems (rigidly anchored to the seabed) or floating systems (with tension legs or catenary cables). OWTs are dynamically-sensitive structures made of a long slender tower with a top-heavy mass, known as Nacelle, to which a heavy rotating mass (hub and blades) is attached. These structures, apart from the variable environmental wind and wave loads, may also be subjected to earthquake related hazards in seismic zones. The earthquake hazards that can affect offshore wind farm are fault displacement, seismic shaking, subsurface liquefaction, submarine landslides, tsunami effects and a combination thereof. Procedures for seismic designing OWTs are not explicitly mentioned in current codes of practice. The aim of the paper is to discuss the seismic related challenges in the analysis and design of offshore wind farms and wind turbine structures. Different types of grounded and floating systems are considered to evaluate the seismic related effects. However, emphasis is provided on Tension Leg Platform (TLP) type floating wind turbine. Future research needs are also identified.

System Reliability for Offshore Wind Turbines: Fatigue Failure

2013 ◽  
Author(s):  
S. Márquez-Domínguez ◽  
J. D. Sørensen
Keyword(s):  
Wind Turbines ◽  
Limit State ◽  
Wind Farms ◽  
Offshore Wind ◽  
Design Standards ◽  
State Equations ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Cost Of Energy ◽  
Wake Effects

Deeper waters and harsher environments are the main factors that make the electricity generated by offshore wind turbines (OWTs) expensive due to high costs of the substructure, operation & maintenance and installation. The key goal of development is to decrease the cost of energy (CoE). In consequence, a rational treatment of uncertainties is done in order to assess the reliability of critical details in OWTs. Limit state equations are formulated for fatigue critical details which are not influenced by wake effects generated in offshore wind farms. Furthermore, typical bi-linear S-N curves are considered for reliability verification according to international design standards of OWTs. System effects become important for each substructure with many potential fatigue hot spots. Therefore, in this paper a framework for system effects is presented. This information can be e.g. no detection of cracks in inspections or measurements from condition monitoring systems. Finally, an example is established to illustrate the practical application of this framework for jacket type wind turbine substructure considering system effects.

Mooring Designs for Floating Offshore Wind Turbines Leveraging Experience From the Oil & Gas Industry

2021 ◽  
Author(s):  
Kai-tung Ma ◽  
Yongyan Wu ◽  
Simen Fodstad Stolen ◽  
Leopoldo Bello ◽  
Menno ver der Horst ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Wind Farms ◽  
Offshore Wind ◽  
Synthetic Fiber ◽  
Extensive Experience ◽  
Gas Industry ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Abstract As renewable energy developers start venturing into deeper waters, the floating offshore wind turbines (FOWTs) are becoming the preferred solutions over fixed supporting structures. Many similarities can be identified between a FOWT and a floating oil & gas facility, such as floater concepts (spar, semi-submersible, tension leg platform, etc) and their mooring system designs. This paper focuses on the mooring designs for FOWTs by leveraging the extensive experience gained from the offshore oil & gas industry. Similarities and differences are highlighted in design criteria, mooring analysis, long-term integrity management, installation method and project execution. The established practices regarding mooring design and analysis are reviewed. Anchor radius is recommended based on water depth by referencing sample mooring designs from the oil & gas industry. Long-term mooring integrity and failure rates are summarized. Meanwhile, a few well-known issues are discussed, such as line break due to fatigue, corrosion on chain, and known issues with components such as clump weights. Regarding mooring installation, the established method for prelay and hook-up is reviewed. Finally, opportunities for cost reduction of mooring systems of FOWTs are presented related to project execution of large scale wind farms as well as potential areas of innovation, such as installation methods, use of synthetic fiber rope, and digitalization. In summary, the state-of-the-art practices from the oil & gas industry are reviewed and documented to benefit the developments of upcoming FOWT projects.

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