• Journal of Advanced Marine Engineering and Technology
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• 제33권7호
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• pp.1012-1016
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• 2009

This paper describes the control and monitoring system for OWEC (Overtopping Wave Energy Converter) which shows the characteristic of power stabilization in overtopping wave energy converter system. Overtopping waves generates different water pressure and the turbine is rotated by this pressure. As a result, overtopping wave energy converter is able to convert wave energy into electricity. Small size of overtopping wave energy converter is developed to simulate the control monitoring system which is able to control power generation and also monitor the system condition. The result shows the reduction of fluctuation from the overtopping wave energy system by the developed control monitoring system. In addition, the DB(Data Base) of test results are contributed to the research and development for OWEC.

• 수산해양교육연구
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• 제27권5호
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• pp.1303-1309
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• 2015

The behavior and flow characteristics of the floating wave energy converter were analyzed by using CFD in this study. The average significant wave height was confirmed as 0.5~2.0m from the Korean coastal sea area. This study was carried out by selecting a range of 1.0~1.6m in the wave height to simulate the operations of realistic wave energy converter system. The principle of a piston wave maker was applied in order to produce periodic wave. The behavior of the wave energy converter and the state of the wave overtopping according to the generated periodic wave were confirmed through the unsteady three-dimensional flow analysis. It was found that the wave overtopping rate according to the generated periodic wave was in range of the 11.6~30.0 kg/s.

• 한국해양공학회지
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• 제19권6호통권67호
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• pp.8-15
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• 2005

Wave energy has been considered to be one of the most promising energy resources for the future, as it is pollution-free and an abundant natural resource. However, since it has drawbacks of non-stationary energy density, it is necessary to change the wave energy into a simple concentrated energy. Progressive waves in a coastal area can be amplified, swashed, and overtopped by a wave overtopping control structure. By conserving the quantity of overflow in a reservoir, the kinetic energy of the waves can be converted to the potential energy with a hydraulic head above the mean sea level. The potential energy in the form of a hydraulic head can be utilized to produce electric power, similar to hydro-electric power generation. This study aims to find the most optimal shape of wave overtopping structure for maximum overtopping volume of sea water; for this purpose, we carried out the wave overtopping experiment in a wave tank, under both regular and irregular wave conditions.

• 한국소음진동공학회논문집
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• 제20권4호
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• pp.323-330
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• 2010

An efficient wave energy converter with new overtopping flow device on which spiral reefs are attached is proposed by Maritime and Ocean Engineering Research Institute in Korea and its candidate substructures such as monopile, tripod and jacket are designed. This study investigates modal characteristics of the substructures by analyzing natural frequencies and mode shapes. Based on the modal analysis results, relative strength, governing modes and some complementary design strategies of each candidate substructure are compared and discussed considering water depth conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.668-676
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• 2017

A two-dimensional numerical investigation is performed to study the influence of slot width of multi-stage stationary floating overtopping wave energy devices on overtopping flow rate and performance. The hydraulic efficiency based on captured crest energy of different device layouts is compared with that of single-stage device to determine the effect of the geometrical design. The results show optimal trends giving a huge increase in overtopping energy. Plots of efficiency versus the relative slot width show that, for multi-stage devices, the greatest hydraulic efficiency is achieved at an intermediate value of the variable within the parametric range considered, relative slot width of 0.15 and 0.2 depending on design layouts. Moreover, an application of adaptive slot width of multi-stage device is investigated. The numerical results show that the overall hydraulic efficiency of non-adaptive and adaptive slot devices are approximately on par. The effect of adaptive slot width on performance can be negligible.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권5호
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• pp.651-659
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• 2018

A multi-level overtopping wave energy converter was designed according to the large tidal range and small wave heights in China. It consists of two reservoirs with sloping walls at different levels. The reservoirs share a common outflow duct and a low-head axial turbine. The experimental study was carried out in a laboratory wave-flume to investigate the overtopping performance of the device. The depth-gauges were used to measure the variation of the water level in the reservoirs. The data was processed to derive the time-averaged overtopping discharges. It was found that the lower reservoir can store wave waters at the low water level and break the waves which try to climb up to the upper reservoir. The upper sloping angle and the opening width of the lower reservoir both have significant effects on the overtopping discharges, which can provide more information to the design and optimization of this type of device.

• 해양환경안전학회지
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• 제29권7호
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• pp.992-1001
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• 2023

OWEC(Overtopping Wave Energy Converter)는 월파된 파도를 이용한 파력발전시스템이라한다. OWEC의 성능 및 안전성은 파고, 주기 등 파도의 특성에 의해 영향을 받는다. 따라서 해역 특성에 따른 OWEC의 최적 형상과 구조안전성에 관한 연구가 필요하다. 본 연구에서는 울릉읍 연안 해양 환경 데이터를 이용하였으며, SPH(Smoothed Particle Hydrodynamics) 입자법 해석을 통해 기존 케이슨 하부 구조에 변화를 준 모델 4개를 비교하여 월파 효율을 분석하였다. 그 결과, 하부 구조의 변경 및 경량화가 가능함을 확인하였다. 최적화 해석을 통해 설계 하중에 내하력을 가지는 하부 구조인 새로운 트러스형 구조를 제안하였다. 이후 부재 직경 및 두께를 설계변수로 하는 사례 연구를 통해 허용응력조건 하에서 구조 안전성의 확보를 확인하였다. 주기적인 파랑 하중을 받기 때문에 제안하는 구조의 고유 진동수와 해당 해역의 파주기를 비교하였으며, 1년 재현 주기의 파랑을 하중으로 한 조화응답해석을 수행하였다. 제안하는 하부 구조는 동일 가진력에서 기존 설계 대비 응답의 크기가 감소하였으며, 기존 대비 32% 이상의 중량 절감을 수행하였다.

• 해양환경안전학회지
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• 제28권1호
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• pp.168-174
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• 2022

월파된 파도를 이용한 파력발전시스템을 월파수류형 파력발전기 OWEC(Overtopping Wave Energy Converter)라고 한다. OWEC의 성능은 발전 시스템은 특성상 파도의 파고와 주기의 영향을 받는다. 파도는 해양에 따라 파고, 주기, 파도 방향 등의 특성이 다르고 이러한 파도의 다양한 특성 때문에 OWEC는 안정적인 전력을 생산하기 어렵다. 따라서 각 바다의 특성에 따른 OWEC의 적절한 형상에 관한 연구가 필요하다. 본 연구에서는 SPH(Smoothed Particle Hydrodynamics) 입자법을 사용하여 OWEC의 램프 설계가 hydraulic efficiency에 미치는 영향을 확인했다. 총 10개의 모델을 설계하였으며, 선택된 매개변수에 따라 램프의 설계 파라미터를 선택하고 사면의 형상을 변경하여 시뮬레이션을 수행하였다. 해석 결과로부터 구한 유량을 기초로 hydraulic efficiency를 산출하였다. 계산된 hydraulic efficiency를 바탕으로 각 변수가 사면의 형상에 따른 월파 성능에 미치는 영향을 확인하였다. 본 연구에서는 특정 해역에 따른 OWEC 램프의 적절한 형상에 대한 방향을 제시하였다.

• Ocean Systems Engineering
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• 제10권4호
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• pp.359-371
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• 2020

The performance of a multi-level overtopping wave energy converter (OWEC) has been numerically and experimentally investigated in a two-dimensional wave tank in order to study the effects of opening width of additional reservoirs. The device is a fixed OWEC consisting of an inclined ramp together with several reservoirs at different levels. A particle-based numerical simulation utilizing the Lattice Boltzmann Method (LBM) is used to simulate the flow behavior around the OWEC. Additionally, an experimental model is also built and tested in a small wave flume in order to validate the numerical results. A comparison in energy captured performance between single-level and multi-level devices has been proposed using the hydraulic efficiency. The enhancement of power capture performance is accomplished by increasing an overtopping flow rate captured by the extra reservoirs. However, a noticeably large opening of the extra reservoirs can result in a reduction in the power efficiency. The overtopping flow behavior into the reservoirs is also presented and discussed. Moreover, the results of hydrodynamic performance are compared with a similar study, of which a similar tendency is achieved. Nevertheless, the LBM simulations consume less computational time in both pre-processing and calculating phases.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.470-475
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• 2019

본 논문에서는 진동수주형(OWC: Oscillating Water Column) 파력발전시스템을 위한 30kW 급 계통연계형 PCS(Power Conversion System)을 다룬다. 해양에너지 중 파력 발전은 삼면이 바다인 반도의 특성을 지닌 한국에 적용하기 적합하고 연안재해 시 파력 발전기가 방파제 역할을 하여 피해를 감소시킬 수 있고, 다른 해상 발전과 개발 대상 적지가 일치하므로 통합하여 효율을 증대 시킬 수 있다. 파력발전 방식은 작동 원리에 따라 가동 물체형과 진동수주형, 월파형 등 여러 형태로 구분하며, 설치 형태에 따라 고정식과 부유식으로 구분된다. 본 논문에서는 구조적으로 안정되고 터빈과 발전기의 유지 보수가 비교적 쉬운 진동수주형을 채택하여, 파력발전용 30kW 계통연계형 PCS 토폴로지 및 모델을 제안하고 계통에 안정적으로 전압을 공급할 수 있는 DC link 전압 제어 등 계통연계 시 필요한 제어방법에 대해 설명하였다. 또한 이를 검증하기 위해 시뮬레이션을 수행하였다.