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.

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 Floating Performance of a Composite Bucket Foundation with an Offshore Wind Tower during Transportation

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 882 ◽  
Author(s):  
Hongyan Ding ◽  
Zuntao Feng ◽  
Puyang Zhang ◽  
Conghuan Le ◽  
Yaohua Guo
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Wind Farms ◽  
Interaction Force ◽  
Offshore Wind ◽  
Construction Technique ◽  
Bucket Foundation ◽  
Offshore Wind Turbines ◽  
One Step

The composite bucket foundation (CBF) for offshore wind turbines is the basis for a one-step integrated transportation and installation technique, which can be adapted to the construction and development needs of offshore wind farms due to its special structural form. To transport and install bucket foundations together with the upper portion of offshore wind turbines, a non-self-propelled integrated transportation and installation vessel was designed. In this paper, as the first stage of applying the proposed one-step integrated construction technique, the floating behavior during the transportation of CBF with a wind turbine tower for the Xiangshui wind farm in the Jiangsu province was monitored. The influences of speed, wave height, and wind on the floating behavior of the structure were studied. The results show that the roll and pitch angles remain close to level during the process of lifting and towing the wind turbine structure. In addition, the safety of the aircushion structure of the CBF was verified by analyzing the measurement results for the interaction force and the depth of the liquid within the bucket. The results of the three-DOF (degree of freedom) acceleration monitoring on the top of the test tower indicate that the wind turbine could meet the specified acceleration value limits during towing.

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 Smart Wireless sensors for Impairment detection of the offshore Wind Turbines

2020 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
Dr. Ranganathan G. ◽  
Dr. Smys S.
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wireless Sensors ◽  
Damage Index ◽  
Wind Farms ◽  
Embedded Software ◽  
Offshore Wind ◽  
Smart Sensors ◽  
Traditional System ◽  
Offshore Wind Turbines

The maintenance of Wind farms located in the off shores are highly challenging as the preservation and the operational availability are tedious. The insufficiency in the traditional system for monitoring the conditions of the wind turbines located in the off shores has made this topic an attractive area of research. The proposed method in the paper utilizes the multiple intelligent smart sensors to detect the impairments in the structure of the wind turbines. The sensors utilized in the proposed method estimates the damage index in the wind turbine by engaging the embedded software. The effectiveness of the proposed method was measured by applying it to the off shore wind turbines. The results obtained evinces the minimized cost and the down time in maintaining the off shore wind farms.

scholarly journals High Voltage DC Transmission Systems for Offshore Wind Farms with Different Topologies

2019 ◽  
Vol 8 (11) ◽  
pp. 2354-2363
Keyword(s):  
High Voltage ◽  
Large Scale ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Future Research ◽  
Voltage Source Converter ◽  
Offshore Wind Farms ◽  
Multi Level ◽  
Level Converter

Theoretical review of various topologies of high voltage DC links in application to off shore wind forms has been studied and analysed. In addition to that, various types of high voltage DC links such as back to back, two terminal, multi-terminal systems has been covered under this study. The Line-Commutated Converters, Voltage Source Converter, Modular Multi-Level Converter as well as some of advanced hybrid high voltage DC topologies in application to off shore wind forms has been reviewed. This study covers complication arising from large-scale wind power generation. The review paper also points out the scope of future research in high voltage DC converters.

New Approach for Offshore Pile Decommissioning With Hydraulic Presses and Floating Panels

2020 ◽  
Author(s):  
Patrick Lehn ◽  
Nils Hinzmann ◽  
Jörg Gattermann
Keyword(s):  
Large Scale ◽  
Competent Authority ◽  
Wind Farms ◽  
Renewable Energies ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Pullout Resistance ◽  
Offshore Wind Turbines ◽  
Technical Solutions ◽  
Large Scale Tests

Abstract Renewable Energies become more and more important in industries and society all over the world. In Germany, offshore wind farms generated 49 % of the renewable energies in 2018. Monopiles are the preferred system for the foundation of offshore wind turbines in water depths up to 40 m. They are authorized by the competent authority for 25 years. When reaching the end of lifetime, the structure inclusive the foundation must be decommissioned. The decommissioning of monopiles will be challenging in the future and can lead to unexpected costs and risks for the owners. Removing the monopiles in it’s entirely ensures the opportunity to reuse the space for new offshore wind farms. The Institute of Geomechanics and Geotechnics of the Technische Universität Braunschweig (IGG-TUBS) obtained the funding for the research program on technical solutions with large-scale tests for decommissioning of offshore monopiles named DeCoMP. Several decommissioning methods such as vibratory extraction, internal dredging, external jet drilling, decommissioning with overpressure and the use of buoyancy force are investigated. The proposed paper will present technical opportunities and issues for extracting the pile with hydraulic presses in combination with a steel framework. Hydraulic presses brace the steel framework with the monopile. Further hydraulic presses, positioned at a certain distance to the pile on the framework, use the seabed as abutments to push out the monopile. In addition, results of a feasibility study to remove monopiles with floatation panels are presented in this paper. This method is based on floating panels, which are attached to the monopile above the mud line. These panels are inflated with air pressure to reach the required amount of buoyancy to overcome the pullout resistance. The decommissioning solutions are compared to point out possible combinations.

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 A Coupled CFD/Multibody Dynamics Analysis Tool for Offshore Wind Turbines With Aeroelastic Blades

2017 ◽  
Author(s):  
Yuanchuan Liu ◽  
Qing Xiao ◽  
Atilla Incecik
Keyword(s):  
Wind Turbine ◽  
Multibody Dynamics ◽  
Wind Turbines ◽  
Large Scale ◽  
Turbine Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Analysis Tool ◽  
Dynamics Analysis ◽  
Offshore Wind Turbines

Aero-elasticity is an important issue for modern large scale offshore wind turbines with long slender blades. The behaviour of deformable turbine blades influences the structure stress and thus the sustainability of blades under large unsteady wind loads. In this paper, we present a fully coupled CFD/MultiBody Dynamics analysis tool to examine this problem. The fluid flow around the turbine is solved using a high-fidelity CFD method while the structural dynamics of flexible blades is predicted using an open source code MBDyn, in which the flexible blades are modelled via a series of beam elements. Firstly, a flexible cantilever beam is simulated to verify the developed tool. The NREL 5 MW offshore wind turbine is then studied with both rigid and flexible blades to analyse the aero-elastic influence on the wind turbine structural response and aerodynamic performance. Comparison is also made against the publicly available data.

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.

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