• Title, Summary, Keyword: Wind Turbine

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Validation Study of Composite Rotor Blade Sectional Analysis Program (Ksec2d-AE) (복합재료 블레이드 단면 해석 프로그램(Ksec2d-AE)의 신뢰성 검증)

  • Bae, Jae-Seong;Kim, Hyun-Sik;Bae, Jin-Kyu;Lim, Tae-Hyun;Hwang, Jae-Min;Jung, Sung Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.4
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    • pp.277-282
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    • 2018
  • In this study, the accuracy and efficiency of a composite rotor blade cross-section analysis program, Ksec2d-AE, which is available at an educational web-based platform called EDISON-CSD, are assessed for possible use in undergraduate structural analysis projects. To this purpose, the convergence of cross-sectional constants by varying the number of finite elements in the cross-section of a wind turbine blade is investigated. The stiffness constants along with the cross-sectional engineering offsets obtained using Ksec2d-AE are validated against a 3D finite element analysis program MSC NASTRAN.

Research trend in Fabrication of Metastable-phase Iron Nitrides for Hard Magnetic Applications (준안정상 기반의 질화철계 영구자석소재 제조연구동향)

  • Kim, Kyung Min;Lee, Jung-Goo;Kim, Kyung Tae;Baek, Youn-Kyoung
    • Journal of Korean Powder Metallurgy Institute
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    • v.26 no.2
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    • pp.146-155
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    • 2019
  • Rare earth magnets are the strongest type of permanent magnets and are integral to the high tech industry, particularly in clean energies, such as electric vehicle motors and wind turbine generators. However, the cost of rare earth materials and the imbalance in supply and demand still remain big problems to solve for permanent magnet related industries. Thus, a magnet with abundant elements and moderate magnetic performance is required to replace rare-earth magnets. Recently, $a^{{\prime}{\prime}}-Fe_{16}N_2$ has attracted considerable attention as a promising candidate for next-generation non-rare-earth permanent magnets due to its gigantic magnetization (3.23 T). Also, metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ exhibits high tetragonality (c/a = 1.1) by interstitial introduction of N atoms, leading to a high magnetocrystalline anisotropy constant ($K_1=1.0MJ/m^3$). In addition, Fe has a large amount of reserves on the Earth compared to other magnetic materials, leading to low cost of raw materials and manufacturing for industrial production. In this paper, we review the synthetic methods of metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ with film, powder and bulk form and discuss the approaches to enhance magnetocrystalline anisotropy of $a^{{\prime}{\prime}}-Fe_{16}N_2$. Future research prospects are also offered with patent trends observed thus far.

Out-Of-Plane Bending Stiffnesses in Offshore Mooring Chain Links Based on Conventional and Advanced Numerical Simulation Techniques (기존/개선 수치 해석 기법을 이용한 계류 체인 링크의 면외 굽힘 강성)

  • Choung, Joonmo;Lee, Jae-bin;Kim, Young Hun
    • Journal of Ocean Engineering and Technology
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    • v.32 no.5
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    • pp.297-309
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    • 2018
  • After an accident involving mooring link failures in an offloading buoy, verification of the fatigue safety in terms of the out-of-plane bending (OPB) and in-plane bending (IPB) moments has become a key engineering item in the design of various floating offshore units. The mooring links for an 8 MW floating offshore wind turbine were selected for this study. To identify the OPB stiffness (OPB moment versus interlink angle), a numerical simulation model, called the 3-link model, is usually composed of three successive chain links closest to the fairlead or chain hawse. This paper introduces two numerical simulation techniques for the 3-link analyses. The conventional and advanced approaches are both based on the prescribed rotation approach (PRA) and direct tension approach (DTA). Comparisons of the nominal stress distributions, OPB stiffnesses, hotspot stress curves, and stress concentration curves are presented. The multiple link analyses used to identify the tension angle versus interlink angle require the OPB stiffness data from the 3-link analyses. A convergence study was conducted to determine the minimum number of links for a multi-link analysis. It was proven that 10 links were sufficient for the multi-link analysis. The tension angle versus interlink angle relations are presented based on multi-link analyses with 10 links. It was found that the subsequent results varied significantly according to the 3-link analysis techniques.

A Study of Wind Turbine by Using ANSYS Program (ANSYS 프로그램을 이용한 풍력발전에 관한 연구)

  • Lee, Dal-Ho;Park, Jung-Cheul
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.11 no.5
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    • pp.565-571
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    • 2018
  • This paper designed the main blade in V-shape and tried to identify the design conditions by changing the main blade number and sub-blade number. Power output and power coefficient increased as main blade number increased. Sample 2 shows a 50% increase in power output compared to sample1. Sample 3 and sample4 increased by 92.8% and 114.7%, respectively. Sample 2 shows a 38.4% increase in power coefficient compared to sample1. Sample 3 and sample4 increased by 92.3% and 107.7%, respectively. Power output and power coefficient increased as sub-blade number increased. Sample 6 shows a 33.3% increase in power output compared to sample 5 and Sample 7 increased by 42.1%. Compared to sample5, efficiency increased by 35.3% for sample 5 and 47.1% for sample 7. The highest power output and power coefficient were measured when main blade and sub-blade were each 30 number. Sample 8 increased power output by 5.6% and power efficiency by 3.7% compared to sample 4. Compared to sample 7, sample 8 increased power efficiency by 12% and power output by 17.3%.

An application of LAPO: Optimal design of a stand alone hybrid system consisting of WTG/PV/diesel generator/battery

  • Shiva, Navid;Rahiminejad, Abolfazl;Nematollahi, Amin Foroughi;Vahidi, Behrooz
    • Advances in Energy Research
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    • v.7 no.1
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    • pp.67-84
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    • 2020
  • Given the recent surge of interest towards utilization of renewable distributed energy resources (DER), in particular in remote areas, this paper aims at designing an optimal hybrid system in order to supply loads of a village located in Esfarayen, North Khorasan, Iran. This paper illustrates the optimal design procedure of a standalone hybrid system which consists of Wind Turbine Generator (WTG), Photo Voltaic (PV), Diesel-generator, and Battery denoting as the Energy Storage System (ESS). The WTGs and PVs are considered as the main producers since the site's ambient conditions are suitable for such producers. Moreover, batteries are employed to smooth out the variable outputs of these renewable resources. To this end, whenever the available power generation is higher than the demanded amount, the excess energy will be stored in ESS to be injected into the system in the time of insufficient power generation. Since the standalone system is assumed to have no connection to the upstream network, it must be able to supply the loads without any load curtailment. In this regard, a Diesel-Generator can also be integrated to achieve zero loss of load. The optimal hybrid system design problem is a discrete optimization problem that is solved, here, by means of a recently-introduced meta-heuristic optimization algorithm known as Lightning Attachment Procedure Optimization (LAPO). The results are compared to those of some other methods and discussed in detail. The results also show that the total cost of the designed stand-alone system in 25 years is around 92M€ which is much less than the grid-connected system with the total cost of 205M€. In summary, the obtained simulation results demonstrate the effectiveness of the utilized optimization algorithm in finding the best results, and the designed hybrid system in serving the remote loads.

A study on collision strength assessment of a jack-up rig with attendant vessel

  • Ma, Kuk Yeol;Kim, Jeong Hwan;Park, Joo Shin;Lee, Jae Myung;Seo, Jung Kwan
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.12 no.1
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    • pp.241-257
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    • 2020
  • The rapid proliferation of oil/gas drilling and wind turbine installations with jack-up rig-formed structures increases structural safety requirements, due to the greater risks of operational collisions during use of these structures. Therefore, current industrial practices and regulations have tended to increase the required accidental collision design loads (impact energies) for jack-up rigs. However, the existing simplified design approach tends to be limited to the design and prediction of local members due to the difficulty in applying the increased uniform impact energy to a brace member without regard for the member's position. It is therefore necessary to define accidental load estimation in terms of a reasonable collision scenario and its application to the structural response analysis. We found by a collision probabilistic approach that the kinetic energy ranged from a minimum of 9 MJ to a maximum 1049 MJ. Only 6% of these values are less than the 35 MJ recommendation of DNV-GL (2013). This study assumed and applied a representative design load of 196.2 MN for an impact load of 20,000 tons. Based on this design load, the detailed design of a leg structure was numerically verified via an FE analysis comprising three categories: linear analysis, buckling analysis and progressive collapse analysis. Based on the numerical results from this analysis, it was possible to predict the collapse mode and position of each member in relation to the collision load. This study provided a collision strength assessment between attendant vessels and a jack-up rig based on probabilistic collision scenarios and nonlinear structural analysis. The numerical results of this study also afforded reasonable evaluation criteria and specific evaluation procedures.

Analysis of Stratified Rock under Vertical Load in Pile Foundation of Wind Turbine Using Circular Foundation Analysis Method with Equivalent Effective Width (등가유효폭을 가진 원형기초해석법을 이용한 풍력발전기 말뚝기초의 연직하중에 대한 층상암반 해석)

  • Kim, Dohan;Park, Sangyeol;Moon, Kyoungtae
    • Journal of The Korean Society of Civil Engineers
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    • v.33 no.6
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    • pp.2411-2425
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    • 2013
  • In the design of pile foundation on the rock layer in the stratified structure with sedimentary and rock layers, the structural analysis of the stratified rock layer is required to determine the failure modes (flexural failure, punching shear failure or end bearing failure) and the bearing capacity of the rock layer. However, the existing usable Elastic Plate Analysis Method (EPAM) suggested by ACI committee 436 and Korean Code Requirements for Structural Foundation Design is very complex, and engineers have many difficulties in using it. Therefore, in this research, we proposed the relatively simple Circular Foundation Analysis Method (CFAM) with the concept and the equation of the equivalent effective width (radius) instead of the complex EPM, and the related equations of bending moment and shear force to be equal to the analysis results of EPAM. As a result, the proposed CFAM using the equivalent effective width (radius) is simple and convenient to use, and the analysis results of it are very good in their accuracies comparing those of EPAM and Finite Element Method.

Economic and Environmental Assessment of a Renewable Stand-Alone Energy Supply System Using Multi-objective Optimization (다목적 최적화 기법을 이용한 신재생에너지 기반 자립 에너지공급 시스템 설계 및 평가)

  • Lee, Dohyun;Han, Seulki;Kim, Jiyong
    • Korean Chemical Engineering Research
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    • v.55 no.3
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    • pp.332-340
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    • 2017
  • This study aims to propose a new optimization-based approach for design and analysis of the stand-alone hybrid energy supply system using renewable energy sources (RES). In the energy supply system, we include multiple energy production technologies such as Photovoltaics (PV), Wind turbine, and fossil-fuel-based AC generator along with different types of energy storage and conversion technologies such as battery and inverter. We then select six different regions of Korea to represent various characteristics of different RES potentials and demand profiles. We finally designed and analyzed the optimal RES stand-alone energy supply system in the selected regions using multiobjective optimization (MOOP) technique, which includes two objective functions: the minimum cost and the minimum $CO_2$ emission. In addition, we discussed the feasibility and expecting benefits of the systems by comparing to conventional systems of Korea. As a result, the region of the highest RES potential showed the possibility to remarkably reduce $CO_2$ emissions compared to the conventional system. Besides, the levelized cost of electricity (LCOE) of the RES-based energy system is identified to be slightly higher than conventional energy system: 0.35 and 0.46 $/kWh, respectively. However, the total life-cycle emission of $CO_2$ ($LCE_{CO2}$) can be reduced up to 470 g$CO_2$/kWh from 490 g$CO_2$/kWh of the conventional systems.

Evaluation of the Shaft Resistance of Drilled-in Steel Tubular Pile in Rock Depending on the Proportion of Annulus Grouting Material (주면고정액 배합비에 따른 암반매입 강관말뚝의 주면지지력 평가)

  • Moon, Kyoungtae;Park, Sangyeol
    • Journal of The Korean Society of Civil Engineers
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    • v.38 no.1
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    • pp.51-61
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    • 2018
  • Foundation of tower structures such as wind turbine, pylon, and chimney have to resist considerably large overturning moment due to long distance from foundations to load point and large horizontal load. Pile foundations subjected to uplift force are needed to economically support such structure even in the case of rock layer. Therefore, this research performed the laboratory model tests with the variables, W/C ratio and sand proportion, to evaluate the effect of the mix proportion of grouting material on shaft resistance. In the case of cement paste, maximum and residual shaft resistance were distributed in uniform range irrespective of the changes of W/C ratio. However in the case of mortar, they were decreased with increasing W/C ratio, while they were increased and then decreased with increasing sand proportion. In the case of no sand, the maximum shaft resistance was about 540~560kPa regardless of the W/C ratio. When the sand proportion was 40%, it was about 770~870kPa depending on W/C ratio, which was about 40~50% higher than that without sand. The optimum proportion found in this research was around 40% of sand proportion and 80~100% of W/C ratio.

Baseline Model Updating and Damage Estimation Techniques for Tripod Substructure (트라이포드 하부구조물의 기저모델개선 및 결함추정 기법)

  • Lee, Jong-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.6
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    • pp.218-226
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    • 2020
  • An experimental study was conducted on baseline model updating and damage estimation techniques for the health monitoring of offshore wind turbine tripod substructures. First, a procedure for substructure health monitoring was proposed. An initial baseline model for a scaled model of a tripod substructure was established. A baseline model was updated based on the natural frequencies and the mode shapes measured in the healthy state. A training pattern was then generated using the updated baseline model, and the damage was estimated by inputting the modal parameters measured in the damaged state into the trained neural network. The baseline model could be updated reasonably using the effective fixity model. The damage tests were performed, and the damage locations could be estimated reasonably. In addition, the estimated damage severity also increased as the actual damage severity increased. On the other hand, when the damage severity was relatively small, the corresponding damage location was detected, but it was more difficult to identify than the other cases. Further studies on small damage estimation and stiffness reduction quantification will be needed before the presented method can be used effectively for the health monitoring of tripod substructures.