• 전기학회논문지P
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• 제66권4호
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• pp.151-157
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• 2017

In this paper, it is the result of analysis of the stability by power system analysis about the influence on the power system when the southwest - offshore wind power demonstration complex is constructed to 60MW and it is linked with the onshore power system. Considering the position of the wind turbine actually installed and the length of the cooperating line, we modeled the wind generators, offshore substation and the turbine step-up transformer. Changes of voltage when internal and external faults occurred is analyzed and the reactive power demand according to the amount of electricity generation is derived. And also phase angle stability and frequency is observed through a transient analysis. This paper clarify that there is no problem in the system when only offshore wind power is linked with the grid and try to present the reactive power amount necessary for maintaining the voltage of the point of cooperation appropriately.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.61-66
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• 2014

The evaporative cooling technology used in Wind generator stator has unique advantages. Combined with the structure of motor stator and operating conditions, this report based on the research project for the evaporative cooling sleeve of the 3.6MW wind generator, introduces the material requirements and structural characteristics of the sleeve, simulates on the stress, displacement and stability by finite analysis method, and tests the products experimentally. The research results show that the epoxy resin-glass materials have a higher strength and better insulation properties, but the evaporative cooling of the wind generator stator sleeve, because of its thin-walled, and the external pressure, so it's the less rigid. Should make full use of the motor stator core structure, increase its stiffness and improve the stability of the epoxy resin-glass sleeve, which for thin-walled the epoxy resinglass sleeve on the successful application of wind turbines has played an important role.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.161-166
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• 2002

As offshore oil fields move towards the deep ocean, the oil production systems such as FPSO are being built these days. Generally, the FPSO is moored by turret mooring lines to keep the position of FPSO. Thus nonlinear motion analysis of moored FPSO must be carried out in the initial design stage because sea environments affect motion of it. In this paper the mathematical model is based on the slow motion maneuvering equations in the horizontal plane considering wave, current and wind forces. The direct integration method is employed to estimate wave loads. The current forces are calculated by using mathematical model of MMG. The turret mooring forces are quasi-statically evaluated by using the catenary equation. The coefficients of a model for wind forces are calculated from Isherwood's experimental data and the variation of wind speed is estimated by wind spectrum according to the guidelines of API-RP2A. The nonlinear motions of FPSO are simulated under external forces due to wave, current, wind including mooring forces in time domain.

• Structural Engineering and Mechanics
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• 제70권3호
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• pp.311-324
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• 2019

Long-span steel suspension bridges develop significant vibrations under the effect of external time-variable loadings because their slenderness. This causes significant stresses variations that could induce fatigue problems in critical components of the bridge. The research outcome presented in this paper includes a fatigue analysis of a long suspension bridge with 3300 meters central suspended span under wind action and train transit. Special focus is made on the counterintuitive interaction effects between train and wind loads in terms of fatigue damage accumulation in the hanger ropes. In fact the coupling of the two actions is shown to have positive effects for some hangers in terms of damage accumulation. Fatigue damage is evaluated using a linear accumulation model (Palmgren-Miner rule), analyses are carried out in time domain by a three-dimensional non-linear finite element model of the bridge. Rational explanation regarding the above-mentioned counterintuitive behavior is given on the basis of the stress time histories obtained for pertinent hangers under the effects of wind and train as acting separately or simultaneously. The interaction between wind and train traffic loads can be critical for a some hanger ropes therefore interaction phenomena within loads should be considered in the design.

• Wind and Structures
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• 제28권4호
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• pp.225-238
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• 2019

In this paper a novel and efficient computational framework to estimate the stress range versus number of cycles curves experienced by a cable due to external excitations (e.g., seismic excitations, traffic and wind-induced vibrations, among others) is proposed. This study is limited to the wind-cable interaction governed by the Vortex Shedding mechanism which mainly rules cables vibrations at low amplitudes that may lead to their failure due to bending fatigue damage. The algorithm relies on a stochastic approach to account for the uncertainties in the cable properties, initial conditions, damping, and wind excitation which are the variables that govern the wind-induced vibration phenomena in cables. These uncertainties are propagated adopting Monte Carlo simulations and the concept of importance sampling, which is used to reduce significantly the computational costs when new scenarios with different probabilistic models for the uncertainties are evaluated. A high fidelity cable model is also proposed, capturing the effect of its internal wires distribution and helix angles on the cables stress. Simulation results on a 15 mm diameter high-strength steel strand reveal that not accounting for the initial conditions uncertainties or using a coarse wind speed discretization lead to an underestimation of the stress range experienced by the cable. In addition, parametric studies illustrate the computational efficiency of the algorithm at estimating new scenarios with new probabilistic models, running 3000 times faster than the base case.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제6권11호
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• pp.437-444
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• 2017

전주(Electric Pole)는 전력 송/배전에 사용되는 지지물로 환경적인 요인의 외력 변화에 민감하다. 전력 설비는 외부 환경변화와 재해로 부터 유지/보수적 관점에서 많은 어려움이 있다. 기상변화는 전주 피해에 주요인으로 작용하며, 경제적으로 미치는 영향이 매우 크다. 가공전선(Aerial Wire)은 온도 영향으로 탄성(Elasticity)변화가 나타나며, 탄성의 변화는 풍속, 풍향 등의 요인에 의해 영향력이 가중된다. 전선에 작용하는 외력은 전주의 피로누적으로 작용된다. 전주의 안전도 평가는 설계 단계에서 이루어지며, 운영중인 전주에 대한 영향도는 고려되지 않는다. 보수/안전성 확보 목적으로 외력의 기상요인 영향도를 분석하는 것은 매우 중요하다. 본 논문에서는 유지/안전성 확보 목적수행을 위해 전주에 설치된 센서노드의 가속도 데이터를 분석하고, 잡음(Noise) 보상 방법으로 칼만필터를 이용했다. 기상 요인별 영향도를 분석하기 위해 고속 푸리에 변환(Fast Fourier Transform)을 수행하고, 주파수 성분별 기상요인 영향도를 분석했다. 영향도 분석 결과 온도, 습도, 일사량, 일조시간, 대기압, 풍향, 풍속의 기상요인 영향이 크게 작용했다. 본 논문에서는 주파수 성분별로 기상요인의 영향도가 다름을 보였으며, 유지보수와 안정성 확보의 목적 달성에 중요한 요소로 작용될 수 있으리라 생각한다.

• 대한조선학회지
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• 제12권1호
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• pp.83-90
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• 1975

In order to establish a stability and buoyancy criteria of a floating vessel, the geometrical property as well as external forces and moments be dealt with. This paper discusses in general terms hidden but more salient factors of forces and moments of both natural and artificial origin, particularly wind, with regard to vessels of more general type such as oil drilling rigs.

• Wind and Structures
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• 제12권4호
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• pp.383-400
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• 2009

Low rise building roofs can be subjected to large fluctuating pressures during a tropical cyclone resulting in fatigue failure of cladding. Following the damage to housing in Tropical Cyclone Tracy in Darwin, Australia, the Darwin Area Building Manual (DABM) cyclic loading test criteria, that loaded the cladding for 10000 cycles oscillating from zero to a permissible stress design pressure, and the Experimental Building Station TR440 test of 10200 load cycles which increased in steps to the permissible stress design pressure, were developed for assessing building elements susceptible to low cycle fatigue failure. Recently the 'Low-High-Low' (L-H-L) cyclic test for metal roofing was introduced into the Building Code of Australia (2007). Following advances in wind tunnel data acquisition and full-scale wind loading simulators, this paper presents a comparison of wind-induced cladding damage, from a "design" cyclone proposed by Jancauskas, et al. (1994), with current test criteria developed by Mahendran (1995). Wind tunnel data were used to generate the external and net pressure time histories on the roof of a low-rise building during the passage of the "design" cyclone. The peak pressures generated at the windward roof corner for a tributary area representative of a cladding fastener are underestimated by the Australian/New Zealand Wind Actions Standard. The "design" cyclone, with increasing and decreasing wind speeds combined with changes in wind direction, generated increasing then decreasing pressures in a manner similar to that specified in the L-H-L test. However, the L-H-L test underestimated the magnitude and number of large load cycles, but overestimated the number of cycles in the mid ranges. Cladding elements subjected to the L-H-L test showed greater fatigue damage than when experiencing a five hour "design" cyclone containing higher peak pressures. It is evident that the increased fatigue damage was due to the L-H-L test having a large number of load cycles cycling from zero load (R=0) in contrast to that produced during the cyclone.

• 한국항해항만학회지
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• 제37권6호
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• pp.655-662
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• 2013

최근 화석 연료의 사용에 따른 문제들로 인해 다양한 그린 에너지들이 주목 받고 있다. 그린 에너지의 한 종류로써 풍력 발전의 원동력인 바람은 육상에서 보다 해상에서 양질의 값이 관측된다. 또한, 부지확보, 소음, 전자파와 같은 육상 풍력 발전의 문제점을 해결할 대안으로써, 또한 더 효율적인 풍력 발전을 위해 해상 풍력 발전의 개발이 주목받고 있다. 이에 따라 해상 풍력에 대한 많은 연구들이 수행되고 있다. 풍력 타워가 해상으로 진출함에 따라 해상 풍력 타워는 점차 거대해지고 있다. 따라서 풍력과 파력을 견뎌내기 위한 안정성이 요구되고 있다. 본 연구에서는 p-y 관계를 이용해 다층 지반의 기초에 작용하는 외력을 계산하였다.

• 한국해안해양공학회지
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• 제4권2호
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• pp.91-107
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• 1992

Heaps(1972)가 사용한 천해균질류에 대한 선형 기본방정식을 수심평균류속과 해수면변리를 계산하는 External mode와 수심변이 유속을 계산하는 Internal mode로 분리시킨 다음, Internal mode식에 Galerkin Method를 적용하였다. Internal mode유속을 수평좌표, 시간에 따라 변하는 계수와 대직좌표에 따라 변하는 Basis function들의 곱의 형태로 선형전개하며, 난류확산계수를 포함하는 2차미분항으로부터 해수면에 Homogeneous boundary condition과 해저면에 Sheared boundary condition이 가해지는 Sturm-Liouville system을 구성, Eigenfunctions 해를 구하여 Basis function으로 사용하였다. 모델의 성능을 검토하기 위하여 수립된 모델을 정상균일풍이 가해지는 1차원 수노에 적용하여 Cooper and Pearce(1977)가 제시한 해저면 비활동조건하의 무한 및 유한수노 연직류원분포에 대한 해석각와 비교하였으며, North Sea 규모의 등수심 장방형 Basin(Heaps' Basin)에 적용하여 정상균일풍에 대한 Heaps(1972)의 계산결과와 비교하였다.