• 한국해양공학회지
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• 제25권5호
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• pp.64-68
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• 2011

The motion responses of a 5-MW floating offshore wind turbine were simulated in regular and irregular waves and its RAOs and significant motion responses were calculated, respectively. The floating offshore wind turbine employed in this simulation was the OC3-Hywind designed by the National Renewable Research Laboratory, USA. The numerical simulation was carried out using MOSES (Multi-Operational Structural Engineering Simulator), which is widely used to analyze and design floating offshore structures in the gas and oil industry.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.184.1-184.1
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• 2010

Floating wind turbines have been suggested as a feasible solution for going further offshore into deeper waters. However, floating platforms cause additional unsteady motions induced by wind and wave conditions, so that it is difficult to predict annual energy output of wind turbines by using conventional power prediction method. That is because sectional inflow condition on a rotor plane is varied by unsteady motion of floating platforms. Therefore, aerodynamic simulation using Vortex Lattice Method(VLM) were used to investigate the influence of motion on the aerodynamic performance of a floating offshore wind turbine. Simulation with individual motion of offshore platform were compared to the case of onshore platform and carried out according to the wave height and the wave angular frequency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.37.2-37.2
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• 2011

Nowadays, offshore wind energy experiences a rapid development because of its wind condition and no noise impact problem. Different from Europe, offshore wind is just started in Asia. More work and research are needed in Korea. In this work, a three-bladed upwind variable speed pitch controlled 5MW wind turbine on a jacket support structure is used. During the simulation, several design load cases are investigated in two different fully coupled aero-hydro-servo-elastic codes. Some critical loads on the foundation are compared and analyzed.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.39-45
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• 2013

Wind power is one of the fastest growing renewable energy sources. In these days, wind turbine shifts from onshore to offshore because the offshore wind farm has a abundant wind resource. However, offshore wind turbine is not easy to access, it has a long downtime when the failures of the wind turbine component occur. Therefore, the appropriate wind turbine maintenance plan is required to meet the economic and reliability of the components. This paper proposes the maintenance planning method based on the RCM(Reliability Centered Maintenance) to determine an economical maintenance cycle to satisfy the appropriate reliability of the wind turbine components. In order to compare the proposed method with the conventional RCM method, critical components are selected in the case study because they have a long downtime and a large amount of total cost.

• 신재생에너지
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• 제7권1호
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• pp.15-21
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• 2011

In recent years, many countries have been endeavoring to exploit the offshore wind energy in terms of overcoming the limitations of on-land wind energy. Considering that mountains cover 70 percent of the Korean Peninsula and arable plains for wind energy are negligibly small, Korean government aggressively drives the offshore wind development of the Korean Peninsula. As part of preliminary investigation of offshore wind resources, KEPCO-RI (Korea Electric Power Corporation-Research Institute) has been analyzing marine buoy datasets measured at 5 positions over the period of 12 years, including estimation of extreme wind speed. It can be observed that variation of yearly wind speed, monthly wind speed as well as frequency distribution of wind direction. Wind classes of buoy sites are estimated by extrapolated average wind speed using log law. In addition, wind turbine class based on IEC code is assessed for evaluation of suitable wind turbine.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.38.2-38.2
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• 2011

A large number of offshore wind turbines with fixed foundations have been installed in water depths up to 30 meters supporting 3-5MW wind turbines. Some floating platform concepts of offshore wind turbines were designed to be suitable for deployment in water depths greater than 60 meters. However the optimal design of this system in water depth 50 meters remains unknown. In this paper, a 5-MW wind turbine located on a TLP type platform was suggested for installation in this water depth. It is moored by a taut mooring line. For controlling the wind turbine always be operated at the upwind direction, one yaw controlling was attached at the tower. To study motion characteristics of this platform, a model was built with a 1/128 scale ratio. The model test was carried out in various conditions, including waves, winds and rotating rotor effect in the Ocean Engineering Wide Tank of the University Of Ulsan (UOU). The characteristic motions of the TLP platform were captured and the effective RAOs were obtained.

• 한국CDE학회논문집
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• 제20권1호
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• pp.84-92
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• 2015

In this study, we describe a method to analysis dynamic behavior of an offshore wind turbine in the frequency domain and expected effects of the method. An offshore wind turbine, which is composed of platform, tower, nacelle, hubs, and blades, can be considered as multibody systems. In general, the dynamic analysis of multibody systems are carried out in the time domain, because the equations of motion derived based on the multibody dynamics are generally nonlinear differential equations. However, analyzing the dynamic behavior in time domain takes longer than in frequency domain. In this study, therefore, we describe how to analysis the system multibody systems in the frequency domain. For the frequency domain analysis, the non-linear differential equations are linearized using total derivative and Taylor series expansions, and then the linearized equations are solved in time domain. This method was applied to analysis of double pendulum system for the verification of its effectiveness, and the equations of motion for the offshore wind turbine was derived with assuming that the wind turbine is rigid multibody systems. Using this method, the dynamic behavior analysis of the offshore wind turbine can be expected to take less time.

• 한국전산구조공학회논문집
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• 제26권4호
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• pp.233-239
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• 2013

신재생, 친환경 에너지에 대한 관심의 증가로 최근 상당수의 풍력 발전기가 설치되고 있다. 특히, 육상과 달리 부지 확보의 어려움도 없고 고품질의 바람을 얻을 수 있다는 점에서 해상 풍력 발전기가 더욱 주목을 받고 있다. 이와 같은 장점을 가진 해상 풍력 발전기는 육상의 조선소 등에서 제작된 후, 해상 크레인을 이용하여 운용 지점까지 이송되어 설치되는데, 이때 그 크기의 거대함과 고가라는 이유로 무엇보다 안전이 보증되어야 한다. 따라서 본 연구에서는 해상 풍력 발전기의 이송 및 설치 시 안전성을 보증하기 위한 근거로서, 다물체계 동역학 기법을 활용하여 해상 크레인에 연결된 해상 풍력 발전기의 동역학 해석을 수행하였다. 그 결과, 본 기법이 해상 풍력 발전기의 이송 및 설치방법에 대한 검증용으로 충분히 활용 가능함을 확인할 수 있었다.

• 대한조선학회논문집
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• 제46권5호
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• pp.536-544
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• 2009

The performance of radars operated near an offshore wind farm region may be degraded due to the distorted signals by wind turbines. This degradation of radar systems includes ghost effects and doppler effects by a tower, nacelle, and turbine blades consisting of the wind turbine. In this paper, electromagnetic wave backscatterings from a offshore wind turbine are numerically simulated in terms of temporal radar cross section and radar cross section spectra, using a quasi-static approach based on physical optics and physical theory of diffraction. The simulations are carried out at 3.05 GHz for the seven yaw angles and four blade pitch angles. From the results, radar cross section values and doppler effect as turbine blades rotate are investigated.

• 대한토목학회논문집
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• 제32권2B호
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• pp.149-152
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• 2012

본 연구는 해상풍력발전기 기초 설계에 사용되는 IEC 61400-3, DNV-OS-J101, GL Wind, EUROCODE, AASHTO 및 국내 설계기준의 설계방법 및 안전율의 정도를 비교, 분석함으로써, 국내에서 해상풍력발전기 기초 설계시 필요한 제반사항을 제공하고자 한다. 해상풍력발전기 기초 설계에 관한 국내외 설계기준을 분석한 결과 설계법은 크게 설계접근법, 하중저항 설계법, 허용응력설계법을 적용하고 있으며, 각 설계법에 따른 안전율 정도를 분석한 결과 하중저항계수 설계법과 설계접근법은 거의 유사한 수준의 안전율을 확보하고 있는 반면, 허용응력설계법에서는 다소 보수적인 안전율을 적용하고 있어 해상풍력발전기 기초의 경제적 설계를 위한 국내 설계기준 개발이 필요할 것으로 판단된다.