• 기계와재료
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• v.22 no.2
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• pp.72-81
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• 2010

본고에서는 유럽, 미국, 일본에서 활발하게 수행되고 있는 해상 풍력발전시스템을 위한 부유식 플랫폼에 대한 연구활동 및 기술내용에 대해서 논하고자 한다. 아직까지 부유식 해상 풍력발전 시스템이 실증되지는 않았지만 현재 실증을 추진하고 있으며, 앞으로 늦어도 10년 내에 부유식 해상풍력 발전단지의 조성이 가시화 될 것으로 예상하고 있다. 본고를 통하여 지금까지 부유식 해상풍력 발전시스템으로 제안된 여러 가지 형태의 개념설계안을 검토하였다. 육지 면적이 좁고 인구밀도가 높은 반면에 삼면이 바다로 둘러싸여 있는 우리나라에서도 부유식 해상 풍력발전 시스템 기술개발이 필요할 것으로 판단된다. 이를 위하여 우선적으로 풍력발전 시스템 자체의 성능을 예측하고 해석할 수 있는 프로그램의 개발과 해상에서 이를 지지하는 플랫폼의 거동예측 프로그램을 결합한 시스템적인 설계해석 프로그램의 자체개발 및 보유가 필요하다. 이를 위해서는 풍력발전 분야의 전문가들뿐만 아니라 플랫폼을 설계할 수 있는 해양공학 분야의 전문가들과의 융합연구가 요망된다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.223-232
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• 2015

The present paper considers the conceptual design of floating wave-offshore wind hybrid power generation system. The worldwide demand for ocean renewable energy is increasing rapidly. Wave and offshore wind energy have been attractive among the various ocean renewable energy sources, and the site to generate electricity from wave and offshore wind accords well together. This means that a hybrid power generation system, which uses wave and offshore wind energy simultaneously has many advantages and several systems have been already developed in Western Europe. A R&D project for a 10 MW class floating wave-offshore wind hybrid power generation system has been also launched in Korea. A semi-submersible platform, which has four vertical columns at each corner of the platform to be connected with horizontal pontoons, was designed for this system considering arrangements of multiple wind turbines and wave energy converters. A mooring system and power cable were also designed based on the metocean data of installation site. In the present paper, those results are presented, and the difficulties and design method in the design of hybrid power generation system are presented.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.455-463
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• 2012

In this study, we calculate dynamic constrained force of tower top and blade root of a floating offshore wind turbine. The floating offshore wind turbine is multibody system which consists of a floating platform, a tower, a nacelle, and a hub and three blades. All of these parts are regarded as a rigid body with six degree-of-freedom(DOF). The platform and the tower are connected with fixed joint, and the tower, the nacelle, and the hub are successively connected with revolute joint. The hub and three blades are connected with fixed joint. The recursive formulation is adopted for constructing the equations of motion for the floating wind turbine. The non-linear hydrostatic force, the linear hydrodynamic force, the aerodynamic force, the mooring force, and gravitational forces are considered as external forces. The dynamic load at the tower top, rotor shaft, and blade root of the floating wind turbine are simulated in time domain by solving the equations of motion numerically. From the simulation results, the mutual effects of the dynamic response between the each part of the floating wind turbine are discussed and can be used as input data for the structural analysis of the floating offshore wind turbine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.77-83
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• 2011

In this study, the dynamic modeling of floating offshore wind turbine system is reported and the dynamic behavior of the platform for the offshore wind turbine system is analyzed. The modeling of the wind load for a floating offshore wind turbine tower is based on the vertical profile of wind speed. The relative Morison equation is employed to obtain the wave load. ADAMS is used to carry out the dynamic analysis of the floating system that should withstand waves and the wind load. Computer simulations for four types of tension leg platforms are performed, and the simulation results for the platforms are compared with each other.

• Bulletin of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.7-12
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• 2014

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.209-215
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• 2017

A large floating offshore wind-wave hybrid power generation system with an area of 150 m2 and four 3 MW class wind turbine generators was installed at each column top. In accordance with the wind turbine arrangement, the wake generated from upstream turbines can adversely affect the power performance and load characteristics of downstream turbines. Therefore, an optimal arrangement design, obtained through a detailed flow analysis focusing on wake interference, is necessary. In this study, to determine the power characteristics and annual energy production (AEP) of individual wind turbines, transient computational fluid dynamics, considering wind velocity variation (8 m/s, 11.7 m/s, 19 m/s, and 25 m/s), was conducted under different platform conditions ($0^{\circ}$, $22.5^{\circ}$, and $45^{\circ}$). The AEP was calculated using a Rayleigh distribution, depending on the wind turbine arrangement. In addition, we suggested an optimal arrangement design to minimize wake losses, based on the AEP.

• Journal of Wind Energy
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• v.14 no.3
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• pp.61-68
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• 2023

This paper aims to perform optimal operation and maintenance with an integrated monitoring system for offshore wind platforms. Based on the wind direction and wind speed data of existing wind farms, a monitoring system was established along with weather and weather data to maximize the operational efficiency of wind farms. Compared to wind power on land, offshore wind power is difficult to maintain due to weather, logistics and geographical limitations. Therefore, economic analysis of actual operation and maintenance is essential for large-scale offshore wind farms. In this paper, the availability of offshore wind farms was analyzed by using personnel resources, parts inventory, Crew Transfer Vessel (CTV) and Specialized service Operation Vessel (SOV) etc. before the actual operation and maintenance of wind farms. A comparative analysis was conducted to determine the optimum operating efficiency and economical maintenance costs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1489-1495
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• 2012

In this study, we perform the structural analysis of a floating offshore wind turbine tower by considering the dynamic response of the floating platform. A multibody system consisting of three blades, a hub, a nacelle, the platform, and the tower is used to model the floating wind turbine. The blades and the tower are modeled as flexible bodies using three-dimensional beam elements. The aerodynamic force on the blades is calculated by the Blade Element Momentum (BEM) theory with hub rotation. The hydrostatic, hydrodynamic, and mooring forces are considered for the platform. The structural dynamic responses of the tower are simulated by numerically solving the equations of motion. From the simulation results, the time history of the internal forces at the nodes, such as the bending moment and stress, are obtained. In conclusion, the internal forces are compared with those obtained from static analysis to assess the effects of wave loads on the structural stability of the tower.

• Journal of Wind Energy
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• v.14 no.4
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• pp.29-42
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• 2023

In this study, research and empirical cases of floating offshore wind turbine systems with a tension-leg platform are investigated, and hydrodynamic and structural characteristics according to platform shapes and characteristics during transportation and installation are confirmed. Most platforms are composed of pontoons or corner columns, and these are mainly located below the waterline to minimize the impact of breaking waves and supplement the lack of buoyancy of the center column. These pontoons and corner columns are designed with a simple shape to reduce manufacturing and assembly costs, and some platforms additionally have reinforcements such as braces to improve structural strength. Most of the systems are assembled in the yard and then moved by tugboat and installed, and some platforms have been developed with a dedicated barge for simultaneous assembly, transportation and installation. In this study, we intend to secure the basic data necessary for the design, transportation, and installation procedures of floating offshore wind turbine systems with a tension-leg platform.

• Journal of Wind Energy
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• v.13 no.4
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• pp.17-25
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• 2022

In this study, the response characteristics of two semi-submersible platforms with an IEA 15 MW reference wind turbine are compared. The nacelle acceleration, platform motion and generator power of FOWT applying a VolturnUS-S platform developed by the University of Maine and PentaSemi platform developed by the Korea Research Institute of Ships and Ocean Engineering are compared in operational conditions. Numerical simulations are performed based on the marine environmental conditions of the U.S east coast. In the FOWT to which the PentaSemi platform is applied, the nacelle acceleration and platform pitch angle are rather high, but the results of both platforms satisfied the design criteria at all operating wind speeds. The platform yaw angle of PentaSemi platform to which a yaw control catenary mooring system is applied is significantly smaller than the platform yaw angle of VolturnUS-S. Also, despite the relatively large nacelle acceleration and platform pitch angle, the generator power is higher on the PentaSemi platform. This means that the generator power dominates the control system rather than the nacelle and platform motion.