Support Structure Optimization for Offshore Wind Turbines With a Genetic Algorithm

2014 ◽  
Author(s):  
Lucía Bárcena Pasamontes ◽  
Fernando Gómez Torres ◽  
Daniel Zwick ◽  
Sebastian Schafhirt ◽  
Michael Muskulus
Keyword(s):  
Genetic Algorithm ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Hot Spot ◽  
Offshore Wind ◽  
Support Structures ◽  
Hot Spot Stress ◽  
Offshore Wind Turbines ◽  
Structural Design Optimization ◽  
The Time Domain

This study considers the use of a genetic algorithm for the structural design optimization of support structures for offshore wind turbines. Member diameters, thicknesses and locations of nodes are jointly optimized. Analysis of each design is performed with a complete wind turbine simulation, for a load case in the time domain. Structural assessment is in terms of fatigue damage, evaluated for each joint using the hot-spot stress approach. This defines performance constraints. Designs are optimized with respect to their weight. The approach has been tested with the modified 4-legged UpWind jacket from the OC4 project. The weight is quickly reduced, convergence slows after about 100 iterations, and few changes occur after 250 iterations. Interestingly, the fatigue constraint is not active for any member, and it is the validity of stress concentration factors that determines the best design, which utilizes less than 90 percent of the available fatigue lifetime. These results of the preliminary study using the genetic algorithm demonstrate that automatic optimization of wind turbine support structures is feasible under consideration of the simplified load approach. Even for complex, multi-member structures such as the considered jacket a weight reduction was achieved.

Fault diagnosis in yaw drive induction motor for wind turbine

2018 ◽  
Vol 42 (6) ◽  
pp. 576-595 ◽  
Author(s):  
Ali Ouanas ◽  
Ammar Medoued ◽  
Mourad Mordjaoui ◽  
Abdesselam Lebaroud ◽  
Djamel Sayad
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Low Frequency ◽  
Offshore Wind ◽  
Discrete Wavelet ◽  
Phase System ◽  
Offshore Wind Turbines ◽  
Three Phase ◽  
The Time Domain ◽  
The Hilbert Transform

Wind turbines are widely exploited throughout the world. The availability and reliability of offshore wind turbines are asking to impose a constant maintenance strategy. In this work, we propose a method that allows filtering the signal of the frequency inverter that feeds the yaw drive used in wind turbine. The redundant information is eliminated via discrete wavelet transform and empirical modal decomposition. The two types of faults are detected from the envelope of the Hilbert transform. The magnitude imbalance detection is carried out in the time domain. The root mean square values of the envelopes of the three-phase system have a good indicator for the fuzzy system to evaluate the severity of the defect. In the frequency domain, the signature of the broken bar fault is located in the low-frequency bandwidth. The harmonics appeared in the spectrum sensitive in amplitude and frequency to the variation of load. Experimental results have demonstrated the accuracy of the proposed method.

scholarly journals Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Petri Net ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Major Repair ◽  
Wind Turbine System ◽  
Periodic Maintenance

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

scholarly journals Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

2021 ◽  
Vol 9 (6) ◽  
pp. 589
Author(s):  
Subhamoy Bhattacharya ◽  
Domenico Lombardi ◽  
Sadra Amani ◽  
Muhammad Aleem ◽  
Ganga Prakhya ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prior Experience ◽  
Physical Modelling ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Foundation Design ◽  
Offshore Wind Turbines ◽  
Sea Bed ◽  
Geological Conditions

Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

Fatigue Life Analysis of Offshore Wind Turbine Support Structures in an Offshore Wind Farm

2018 ◽  
Author(s):  
Bryan Nelson ◽  
Yann Quéméner
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
The Body ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Analysis Tool ◽  
Support Structures ◽  
Offshore Wind Farm ◽  
Actuator Disk

This study evaluated, by time-domain simulations, the fatigue lives of several jacket support structures for 4 MW wind turbines distributed throughout an offshore wind farm off Taiwan’s west coast. An in-house RANS-based wind farm analysis tool, WiFa3D, has been developed to determine the effects of the wind turbine wake behaviour on the flow fields through wind farm clusters. To reduce computational cost, WiFa3D employs actuator disk models to simulate the body forces imposed on the flow field by the target wind turbines, where the actuator disk is defined by the swept region of the rotor in space, and a body force distribution representing the aerodynamic characteristics of the rotor is assigned within this virtual disk. Simulations were performed for a range of environmental conditions, which were then combined with preliminary site survey metocean data to produce a long-term statistical environment. The short-term environmental loads on the wind turbine rotors were calculated by an unsteady blade element momentum (BEM) model of the target 4 MW wind turbines. The fatigue assessment of the jacket support structure was then conducted by applying the Rainflow Counting scheme on the hot spot stresses variations, as read-out from Finite Element results, and by employing appropriate SN curves. The fatigue lives of several wind turbine support structures taken at various locations in the wind farm showed significant variations with the preliminary design condition that assumed a single wind turbine without wake disturbance from other units.

scholarly journals A Surface Ice Module for Wind Turbine Dynamic Response Simulation Using FAST

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Bingbin Yu ◽  
Dale G. Karr ◽  
Huimin Song ◽  
Senu Sirnivas
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Response ◽  
Simulation Software ◽  
Offshore Wind ◽  
Foundation Soil ◽  
Offshore Wind Turbines ◽  
Ice Failure ◽  
Lock In

Developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind turbines subjected to forces resulting from ice impact on the turbine support structure. The conditions considered in this module are specifically addressed in the International Organization for Standardization (ISO) standard 19906:2010 for arctic offshore structures design consideration. Special consideration of lock-in vibrations is required due to the detrimental effects of such response with regard to fatigue and foundation/soil response. The use of FAST for transient, time domain simulation with the new ice module is well suited for such analyses.

Comparison of Spar and Semisubmersible Floater Concepts of Offshore Wind Turbines Using Long-Term Analysis

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hasan Bagbanci ◽  
D. Karmakar ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Transfer Functions ◽  
Probability Distributions ◽  
Offshore Wind ◽  
Short Term ◽  
Offshore Wind Turbines ◽  
Floating Wind Turbine ◽  
Offshore Floating Wind Turbine

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.

scholarly journals A Review of Recent Advancements in Offshore Wind Turbine Technology

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 579
Author(s):  
Taimoor Asim ◽  
Sheikh Zahidul Islam ◽  
Arman Hemmati ◽  
Muhammad Saif Ullah Khalid
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Offshore Wind ◽  
System Level ◽  
Offshore Wind Turbine ◽  
Component Level ◽  
Foundation Design ◽  
Offshore Wind Turbines

Offshore wind turbines are becoming increasingly popular due to their higher wind energy harnessing capabilities and lower visual pollution. Researchers around the globe have been reporting significant scientific advancements in offshore wind turbines technology, addressing key issues, such as aerodynamic characteristics of turbine blades, dynamic response of the turbine, structural integrity of the turbine foundation, design of the mooring cables, ground scouring and cost modelling for commercial viability. These investigations range from component-level design and analysis to system-level response and optimization using a multitude of analytical, empirical and numerical techniques. With such wide-ranging studies available in the public domain, there is a need to carry out an extensive yet critical literature review on the recent advancements in offshore wind turbine technology. Offshore wind turbine blades’ aerodynamics and the structural integrity of offshore wind turbines are of particular importance, which can lead towards system’s optimal design and operation, leading to reduced maintenance costs. Thus, in this study, our focus is to highlight key knowledge gaps in the scientific investigations on offshore wind turbines’ aerodynamic and structural response. It is envisaged that this study will pave the way for future concentrated efforts in better understanding the complex behavior of these machines.

scholarly journals Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

2021 ◽  
Vol 11 (24) ◽  
pp. 11665
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chao Wang ◽  
Yuangang Tu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Included Angle ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

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