scholarly journals Effect of Tensile Force for Wear Performance of Mooring Chain

2018 ◽  
Author(s):  
Koji Gotoh ◽  
Masataka Nakagawa ◽  
Koji Murakami ◽  
Tomoaki Utsunomiya
Keyword(s):  
Wind Turbine ◽  
Deep Sea ◽  
Evaluation Method ◽  
Tensile Force ◽  
Green Energy ◽  
Economic Losses ◽  
Maintenance Cost ◽  
Element Analysis ◽  
Floating Wind Turbine ◽  
Mooring Chain

Floating wind turbine facilities, which are installed in the deep sea area, plays an essential role to promote the green energy application. One of the problems associated with the commercialization of facilities installed in the deep sea is the reduction of the maintenance cost of mooring chain, because breaking of the mooring chain caused by the wear between links leads to enormous economic losses. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. Experimental facility to reproduce the wear caused by sliding between links in actual scale applied for floating wind turbine, which had been proposed by the authors, was updated and the wear tests was conducted by setting some tensile force conditions between the links. Besides, procedure of the nonlinear finite element analysis was improved to estimate the behaviour of wearing between links. From experiments and numerical analysis, it has been confirmed that the tensile force between links is an important factor of the wear amount between links.

Wear Performance of Mooring Chain in Wet Environment With Substitute Ocean Water

2019 ◽  
Author(s):  
Koji Gotoh ◽  
Tetsuya Ueda ◽  
Koji Murakami ◽  
Tomoaki Utsunomiya
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wind Turbine ◽  
Deep Sea ◽  
Green Energy ◽  
Maintenance Cost ◽  
Ocean Water ◽  
Element Analysis ◽  
Wear Performance ◽  
Floating Wind Turbine

Abstract Floating wind turbine facilities installed in deep sea areas play an essential role in the promotion of green energy. One of the problems associated with the commercialization of facilities installed in the deep sea is the maintenance cost of mooring chains, because they are expensive and wear between links leads to chain breakage. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. An experimental facility to reproduce the wear caused by sliding between links at the scale of an actual floating wind turbine was developed to investigate the wear performance in seawater conditions, and wear tests were conducted. Substitute ocean water was applied to the experiment instead of seawater. In addition, a procedure for nonlinear finite element analysis was improved to estimate the behaviour of wear between links. Measured stress versus strain relations of the links was considered in the finite element analysis. The experiments and numerical analysis confirmed that the amount of wear in the substitute ocean water was less than that obtained in dry air and that the tensile force between links is an important factor for the degree of wear between links.

scholarly journals Wear Performance of the Mooring Chain Used in Floating Wind Turbines

2017 ◽  
Author(s):  
Koji Gotoh ◽  
Koji Murakami ◽  
Masataka Nakagawa ◽  
Tomoaki Utsunomiya
Keyword(s):  
Wind Turbine ◽  
Evaluation Method ◽  
Tensile Force ◽  
Wear Test ◽  
Element Model ◽  
Offshore Wind ◽  
Floating Body ◽  
Floating Wind Turbine ◽  
Wear Evaluation ◽  
Mooring Chain

To produce offshore wind power generation plants, deep-sea floating wind turbine facilities are required. Commercial installation of floating wind turbine facilities requires a reduction of the mooring cost. Mooring chain breaks due to progressive wear will lead to enormous damages. Therefore, a quantitative wear evaluation method for mooring chains needs to be established. In this study, an experimental setup was constructed to reproduce the wearing phenomenon in mooring chains due to the motion of the floating body induced by waves, and its usefulness was confirmed. The result of the wear test conducted in this study suggests that the tensile force between links affects the degree of wear. Additionally, numerical simulations were performed using a finite element model with measured wear characteristics of the link material to reproduce the phenomenon of wear between links and confirmed that the wear phenomenon could be represented by numerical simulation.

Quantitative Wear Estimation for Mooring Chain of Floating Structures and its Validation

2019 ◽  
Author(s):  
Takaaki Takeuchi ◽  
Tomoaki Utsunomiya ◽  
Koji Gotoh ◽  
Iku Sato
Keyword(s):  
Estimation Method ◽  
Offshore Wind ◽  
Floating Body ◽  
Maintenance Cost ◽  
Offshore Wind Turbine ◽  
Lumped Mass ◽  
Sliding Angle ◽  
Mass Model ◽  
Element Analysis ◽  
Mooring Chain

Abstract For reducing maintenance cost of floating offshore wind turbine structures, it is necessary to establish quantitative wear estimation method for the mooring chains. In this paper, attempts have been made to improve the accuracy and applicability of the estimation method in the following steps. By using the wear analysis method between the links of mooring chain that Gotoh et al. investigated with the finite element analysis software (MSC. Marc), the expression of the wear amount was obtained, which was a proportional functional form associated with sliding angle and tension. The relative sliding angle and tension between links were analyzed by using a multibody dynamics software (MSC. Adams). A spar-type floater moored with three catenary mooring lines at Goto, Nagasaki prefecture, Japan was analyzed. Here, the floating body was modelled as a rigid body and mooring chains were modelled by mass-spring (lumped mass) model. From these results, the wear amounts calculated by using the estimation formula and relative sliding angle and tension between links were compared with the measured wear amounts for mooring chain of the floater which was deployed for about one-year at Goto. The cases with only waves and those with wind and waves were analyzed. From the comparison between the simulation results and the measured ones, it was found that the proposed method can fairly predict the wear amount of mooring chains. However, it was also found that the proposed method has a tendency to overestimate the measured results. These reasons were discussed in the paper.

Evaluation of Deep-Water Floating Wind Turbine to Power an Isolated Water Injection System

2021 ◽  
Author(s):  
Khalid S. Khan ◽  
Isabelle V. M. dos Santos ◽  
Guilherme B. dos Santos ◽  
Maurício B. C. Salles ◽  
Renato M. Monaro
Keyword(s):  
Wind Turbine ◽  
Oil Recovery ◽  
Water Injection ◽  
High Energy ◽  
Green Energy ◽  
Injection System ◽  
Brazilian Coast ◽  
Diesel Generator ◽  
Basic Premise ◽  
Floating Wind Turbine

Abstract The main objective of this paper is to evaluate the use of floating wind turbines for isolated offshore systems. The energy analysis is a vital step at the initial phase of the project to define topologies that will be able to feed subsea systems, a water injection system is considered as a example. The first location that we decided to look in detail is one of the largest oil regions discovered in the last hundred years and it is located on the Brazilian coast. It is important to highlight that the development is on the technological frontier of a new type of floating wind turbine application for deep waters. The focus of the study is to validate the perks of this application, such as, the production of clean and green energy capable enough to satisfy the load requirements of a Water Injection Systems (WIS) for Oil and Gas (O&G) production, chosen among other possibilities of subsea systems as an example. Water injection is effective to improve the oil recovery in reservoirs, but conventionally involves high energy consumption, significant emissions and expensive infrastructure. This work investigates different configurations combining a wind turbine, diesel generator and batteries to supply power to the off-grid load, with the basic premise that WIS can follow the generation available from the wind turbine, since it does not require a fixed injection rate. In the energetic point of view, the main result shows that the use of wind turbine and li-ion battery can cut emissions by half and increase the energy efficiency of the system.

scholarly journals Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles

2019 ◽  
Vol 9 (23) ◽  
pp. 5258
Author(s):  
Fang Wang ◽  
Mian Wu ◽  
Genqi Tian ◽  
Zhe Jiang ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Material Selection ◽  
High Strength ◽  
External Pressure ◽  
Element Analysis ◽  
Ballast Tank ◽  
Material Inhomogeneity ◽  
Comprehensive Properties ◽  
Ultimate Cause ◽  
Flat Cover

A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials.

Fluid-structure interaction and stress analysis of a floating wind turbine

2021 ◽  
Vol 78 ◽  
pp. 102970
Author(s):  
B. Wiegard ◽  
M. König ◽  
J. Lund ◽  
L. Radtke ◽  
S. Netzband ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Stress Analysis ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Floating Wind Turbine

A novel conceptual design of a dynamically positioned floating wind turbine

2021 ◽  
Vol 221 ◽  
pp. 108528
Author(s):  
Shengwen Xu ◽  
Motohiko Murai ◽  
Xuefeng Wang ◽  
Kensaku Takahashi
Keyword(s):  
Wind Turbine ◽  
Conceptual Design ◽  
Floating Wind Turbine

scholarly journals Power Electric Transformer Fault Diagnosis Based on Infrared Thermal Images Using Wasserstein Generative Adversarial Networks and Deep Learning Classifier

Electronics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1161
Author(s):  
Kuo-Hao Fanchiang ◽  
Yen-Chih Huang ◽  
Cheng-Chien Kuo
Keyword(s):  
Deep Learning ◽  
Fault Diagnosis ◽  
Monitoring System ◽  
Absolute Difference ◽  
Generative Adversarial Networks ◽  
Economic Losses ◽  
Maintenance Cost ◽  
Full Time ◽  
Noise Interference ◽  
In Series

The safety of electric power networks depends on the health of the transformer. However, once a variety of transformer failure occurs, it will not only reduce the reliability of the power system but also cause major accidents and huge economic losses. Until now, many diagnosis methods have been proposed to monitor the operation of the transformer. Most of these methods cannot be detected and diagnosed online and are prone to noise interference and high maintenance cost that will cause obstacles to the real-time monitoring system of the transformer. This paper presents a full-time online fault monitoring system for cast-resin transformer and proposes an overheating fault diagnosis method based on infrared thermography (IRT) images. First, the normal and fault IRT images of the cast-resin transformer are collected by the proposed thermal camera monitoring system. Next is the model training for the Wasserstein Autoencoder Reconstruction (WAR) model and the Differential Image Classification (DIC) model. The differential image can be acquired by the calculation of pixel-wise absolute difference between real images and regenerated images. Finally, in the test phase, the well-trained WAR and DIC models are connected in series to form a module for fault diagnosis. Compared with the existing deep learning algorithms, the experimental results demonstrate the great advantages of the proposed model, which can obtain the comprehensive performance with lightweight, small storage size, rapid inference time and adequate diagnostic accuracy.

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