Localizing and quantifying structural damage by means of a beetle swarm optimization algorithm

2020 ◽  
pp. 136943322095682
Author(s):  
Yufeng Jiang ◽  
Shuqing Wang ◽  
Yingchao Li
Keyword(s):  
Wind Turbine ◽  
Structural Damage ◽  
Experimental Studies ◽  
Measurement Data ◽  
Offshore Wind ◽  
Vibration Measurement ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Swarm Optimization ◽  
Random Direction

An efficient meta-heuristic algorithm, named beetle swarm optimization (BSO), is proposed to localize and quantify structural damage using limited vibration measurement data. The beetle antennae search (BAS) algorithm that imitats a random walking mechanism in nature was recently developed to solve the optimization problem. However, the ratio of convergence of this algorithm significantly relys on the random direction and deviation for high-dimensional problems. To overcome this shortcoming, the BSO inspired by the swarm intelligence strategy is proposed. In the iterative search process of the BSO, each beetle swarm moves in a random direction like the BAS and the swarm of beetles is cognitive with the optimal one for the searching behavior. Consequently, the optimal one is updated step by step until a better beetle appears. To demonstrate the capability and robustness of the BSO, numerical and experimental studies using limited vibration measurement data of an offshore wind turbine structure are carried out for structural damage identification. An novel objective function is established by combining natural frequencies with mode shapes of the structure. The numerical results show that the BSO can accurately localize and quantify various types of damage even in a noise and temperature variations polluted environment. Moreover, it has higher accuracy and faster convergence speed than the BAS and the particle swarm optimization (PSO) algorithms. These promising performances could contribute to establishing a structural monitoring system for safety assurance of wind turbine structures.

Structural Dynamics and Load Analysis of Large Offshore Wind Turbines in Western Gulf of Mexico Shallow Water

2014 ◽  
Author(s):  
Ling Ling Yin ◽  
King Him Lo ◽  
Su Su Wang
Keyword(s):  
Gulf Of Mexico ◽  
Wind Turbine ◽  
Shallow Water ◽  
Structural Dynamics ◽  
Natural Frequencies ◽  
Offshore Wind ◽  
Normal Operation ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Support Structure

In this paper, a study is conducted on wind and metocean loads and associated structural dynamics of a 13.2-MW large offshore wind turbine in Western Gulf of Mexico (GOM) shallow water. The offshore wind turbine considered includes a rotor with three 100-meter long blades and a mono-tower support structure. Natural frequencies and mode shapes of the blades and the mono-tower are determined first and used subsequently to establish a Campbell diagram for safe wind turbine operation. The results show that hydrodynamic added mass has little effect on the natural frequencies and mode shapes of the support structure but it introduces, in part, appreciable effects on loads carried by the turbine when the blades are pitched at wind speeds above the rated speed. Also determined, for normal operation and extreme metocean conditions (i.e., 100-year return hurricanes), are normal thrust on the wind rotor, blade-tip displacement, overturning moment and tower-top displacement sustained by the wind turbine.

Corrosion Mechanism on Offshore Wind Turbine Blade in Salt Fog Environment

2013 ◽  
Vol 432 ◽  
pp. 258-262 ◽  
Author(s):  
Xiao Hui Dong ◽  
Tie Jun Yuan ◽  
Ru Hong Ma
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Structural Damage ◽  
Turbine Blades ◽  
Wind Turbine Blade ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Final Conclusion ◽  
Corrosion Mechanism ◽  
Salt Fog

Targeted at the phenomenon of offshore wind turbine blades cracking and tearing up, the corrosion mechanism on offshore wind turbine blade in salt fog environment is researched. By means of analyzing the blades structural damage and the corrosion in salt fog environment, the main damage forms of the blades can be summed up with a further view to discussing and analyzing the corrosion mechanism on offshore wind turbine blade in salt fog environment from the perspective of both physical and chemical corrosion. A final conclusion is reached which shows that the pitted surface of the blade developed from the pumping and milling of sand blown by wind is the incentive and hydrone diffusion and ultraviolet radiation are the main factors that lead to the aging of materials and corrosion of blades.

Numerical and experimental investigation of modal-energy-based damage localization for offshore wind turbine structures

2018 ◽  
Vol 21 (10) ◽  
pp. 1510-1525 ◽  
Author(s):  
Yingchao Li ◽  
Min Zhang ◽  
Wenlong Yang
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Strain Energy ◽  
Offshore Wind ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Energy Index ◽  
Modal Strain Energy ◽  
Modeling Errors ◽  
Energy Indices

Offshore wind turbine structures are prone to deterioration and damage during their service life in harsh marine environment. To explore highly efficient and robust damage detection methods for offshore wind turbine structures, three well-known modal strain energy indices are reviewed first and then a new index named total modal energy method is proposed. The innovation of the new index is the simultaneous use of modal strain energy and modal kinetic energy. To investigate the feasibility and robustness of the four modal-energy-based methods, numerical and experimental studies are conducted on a tripod-type offshore wind turbine structure with simulated and measured data. It is indicated that all the four modal-energy-based methods work well with limited incomplete modal data, especially for the single-damage cases. While for the cases of multiple damage locations, the new total modal energy index significantly outperforms the traditional modal strain energy indices. Moreover, high robustness is shown for the indices, when the measured mode shapes of undamaged and damaged structures are polluted with the same noise level. However, when their noise levels have some difference, two of the modal strain energy indices turn invalid, but the new total modal energy index still shows stronger robustness. As frequencies are also used in the total modal energy index, its robustness to the noise in modal frequencies is also studied. It is shown that the results are slightly affected by the measurement noise in modal frequencies. Besides, the influence of finite element modeling errors is also investigated with both simulated and experimental data. Results show that all the four modal-energy-based methods are all very stable and insensitive to certain modeling errors. So, finite element model updating is not necessary in the test structure herein.

scholarly journals Structural health monitoring of offshore wind turbines using automated operational modal analysis

2014 ◽  
Vol 13 (6) ◽  
pp. 644-659 ◽  
Author(s):  
Christof Devriendt ◽  
Filipe Magalhães ◽  
Wout Weijtjens ◽  
Gert De Sitter ◽  
Álvaro Cunha ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Wind Turbines ◽  
Operational Modal Analysis ◽  
Offshore Wind ◽  
Dynamic Monitoring ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Complex Frequency ◽  
Offshore Wind Turbines

This article will present and discuss the approach and the first results of a long-term dynamic monitoring campaign on an offshore wind turbine in the Belgian North Sea. It focuses on the vibration levels and modal parameters of the fundamental modes of the support structure. These parameters are crucial to minimize the operation and maintenance costs and to extend the lifetime of offshore wind turbine structure and mechanical systems. In order to perform a proper continuous monitoring during operation, a fast and reliable solution, applicable on an industrial scale, has been developed. It will be shown that the use of appropriate vibration measurement equipment together with state-of-the art operational modal analysis techniques can provide accurate estimates of natural frequencies, damping ratios, and mode shapes of offshore wind turbines. The identification methods have been automated and their reliability has been improved, so that the system can track small changes in the dynamic behavior of offshore wind turbines. The advanced modal analysis tools used in this application include the poly-reference least squares complex frequency-domain estimator, commercially known as PolyMAX, and the covariance-driven stochastic subspace identification method. The implemented processing strategy will be demonstrated on data continuously collected during 2 weeks, while the wind turbine was idling or parked.

scholarly journals Investigation on Optimization Design of Offshore Wind Turbine Blades based on Particle Swarm Optimization

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1972 ◽  
Author(s):  
Yong Ma ◽  
Aiming Zhang ◽  
Lele Yang ◽  
Chao Hu ◽  
Yue Bai
Keyword(s):  
Particle Swarm Optimization ◽  
Wind Turbine ◽  
Optimization Design ◽  
Oscillation Amplitude ◽  
Particle Swarm ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Swarm Optimization ◽  
Wind Speeds ◽  
Floating Wind Turbine

Offshore wind power has become an important trend in global renewable energy development. Based on a particle swarm optimization (PSO) algorithm and FAST program, a time-domain coupled calculation model for a floating wind turbine is established, and a combined optimization design method for the wind turbine’s blade is developed in this paper. The influence of waves on the power of the floating wind turbine is studied in this paper. The results show that, with the increase of wave height, the power fluctuation of the wind turbine increases and the average power of the wind turbine decreases. With the increase of wave period, the power oscillation amplitude of the wind turbine increases, and the power of the wind turbine at equilibrium position decreases. The optimal design of the offshore floating wind turbine blade under different wind speeds is carried out. The results show that the optimum effect of the blades is more obvious at low and mid-low wind speeds than at rated wind speeds. Considering the actual wind direction distribution in the sea area, the maximum power of the wind turbine can be increased by 3.8% after weighted optimization, and the chord length and the twist angle of the blade are reduced.

A Consistent Structural Damping Model for Integrated and Superelement Modelling of Offshore Wind Turbine Support Structures in Wind Turbine Design Software Bladed

2019 ◽  
Author(s):  
William Collier
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Integrated Modelling ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Natural Mode ◽  
Structural Damping ◽  
Support Structure ◽  
Modal Damping ◽  
Modelling Approaches

Abstract In aero-elastic simulation of offshore wind turbines, the support structure can be modelled using an “integrated” approach, where the jacket and tower and modelled explicitly as one structural body, or a “superelement” approach, where the jacket part of the support structure is included as a superelement. For integrated modelling, vibration mode shapes are calculated for the whole support structure. For a superelement approach, separate mode shapes are defined for superelement and the tower. The different modal basis makes it difficult to align the structural damping definition for the two approaches, meaning that manual tuning of the modal damping ratios has previously been necessary to achieve equivalent damping on the whole support structure for the two approaches. To provide a consistent damping approach, it is proposed to specify modal damping ratios or Rayleigh damping on a modal basis which is common to the two approaches: the support structure natural mode shapes. When damping is specified on the natural modes of the support structure, equivalent support structure damping is observed for superelement and integrated modelling approaches. This allows the target support structure damping ratios to be achieved easily and also facilitates studies to compare the superelement and integrated modelling approaches.

scholarly journals Demonstration Experiment and Numerical Simulation Analysis of Full-Scale Barge-Type Floating Offshore Wind Turbine

2020 ◽  
Vol 8 (11) ◽  
pp. 880
Author(s):  
Ko Matias Adrian Kosasih ◽  
Hideyuki Suzuki ◽  
Hideyuki Niizato ◽  
Shigeki Okubo
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Measurement Data ◽  
Offshore Wind ◽  
Extreme Condition ◽  
Offshore Wind Turbine ◽  
Complex Flow ◽  
Development Organization ◽  
Floating Offshore Wind Turbines ◽  
Simulation Results

The development of Floating Offshore Wind Turbines (FOWT) has been progressing steadily. To utilize the moderate water depth of 50–100 m ocean space around Japan, a barge-type FOWT was installed in Kitakyushu as part of a demonstration project conducted by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. The FOWT mounts a 3 MW two-bladed wind turbine with blade diameter of 100 m and hub height of 72 m. The barge-type floating support structure is equipped with a moonpool in the center and a skirt at its bottom and is moored with 9 lines of catenary chains. To investigate the dynamic behavior of the barge-type FOWT in extreme condition and the validity of the numerical simulation in modeling the effect of the complex flow around the floating structure to the FOWT’s motion response, the FOWT’s motion data during typhoon Tapah on 23 September 2019 were measured and compared with the simulation results. As the results, the simulation results showed a good agreement in general to the measurement data. However, some shifts in the peak frequency of the simulation’s motion spectrum and a disagreement in waves with shorter wave periods were also observed. The possible causes of these differences are discussed thoroughly in this paper.

The effect of the TMD on the vibration of an offshore wind turbine considering three soil-pile-interaction models

2021 ◽  
pp. 136943322110083
Author(s):  
Mouafo Teifouet Armand Robinson ◽  
Zhenyu Wang
Keyword(s):  
Power Series ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Mode Shapes ◽  
Offshore Wind Turbine ◽  
Series Method ◽  
Power Series Method ◽  
Mass Damper ◽  
Pile Interaction ◽  
Homogeneous Soil

In this paper we propose the use of the power series method and the Newmark-Beta algorithm to study the mitigation by the tuned mass damper (TMD) of an offshore wind turbine(OWT). The monopile of the OWT is taken as slender beam buried in a homogeneous soil while the tower is considered as tapered slender beam. Mathematically, both monopile and tower are modeled as elastic Euler-Bernoulli beams, with a point mass at the tower top representing the rotor nacelle assembly (RNA). First of all, the power series method is utilized to calculate the first natural frequencies of AF and CS models. The obtained results are compared with the first natural frequency of DS model obtained from FEM-Abaqus with good satisfaction. Next, the obtained mode shapes are used to establish the system of ordinary differential equations (ODE) governing the dynamic of OWT subjected to a TMD. Afterwards, the Newmark-Beta algorithm is employed to solve the ODE. Accuracy of the introduced approach is verified by setting a comparison between our results with those obtained using FEM-Abaqus. Finally, the influence of several parameters on the performance of TMD is shown in some plots.

scholarly journals Transient LES of an offshore wind turbine

2017 ◽  
Vol 2 (2) ◽  
pp. 603-614 ◽  
Author(s):  
Lukas Vollmer ◽  
Gerald Steinfeld ◽  
Martin Kühn
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Mesoscale Model ◽  
Sampling Rate ◽  
Measurement Data ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Synoptic Wind

Abstract. The estimation of the cost of energy of offshore wind farms has a high uncertainty, which is partly due to the lacking accuracy of information on wind conditions and wake losses inside of the farm. Wake models that aim to reduce the uncertainty by modeling the wake interaction of turbines for various wind conditions need to be validated with measurement data before they can be considered as a reliable estimator. In this paper a methodology that enables a direct comparison of modeled with measured flow data is evaluated. To create the simulation data, a model chain including a mesoscale model, a large-eddy-simulation (LES) model and a wind turbine model is used. Different setups are compared to assess the capability of the method to reproduce the wind conditions at the hub height of current offshore wind turbines. The 2-day-long simulation of the ambient wind conditions and the wake simulation generally show good agreements with data from a met mast and lidar measurements, respectively. Wind fluctuations due to boundary layer turbulence and synoptic-scale motions are resolved with a lower representation of mesoscale fluctuations. Advanced metrics to describe the wake shape and development are derived from simulations and measurements but a quantitative comparison proves to be difficult due to the scarcity and the low sampling rate of the available measurement data. Due to the implementation of changing synoptic wind conditions in the LES, the methodology could also be beneficial for case studies of wind farm performance or wind farm control.

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