Earticle

This paper is to study SOFC(Solid Oxide Fuel Cell) technology which is becoming increasingly more important in recent power development market. I will propose the most suitable fuel cell type through efficiency analysis by type of fuel cell in operation. In this paper, I analyzed the characteristics of SOFC development, theoretical study of the system technology and the level of progress in SOFC technology for each generation. In conclusion, through analysis of the operation data of the installed and operating fuel cell power generation system, it was found that SOFC is 45% more efficient than PAFC and 25% more efficient than MCFC.

Floating solar power generation is rapidly emerging as an alternative technology to land-based solar power generation around the world, and there are many advantages to developing and operation floating solar power, but it is a buoyant body that floats solar power modules and structures such as typhoons, tsunami, and wave heights. Research and development is actively underway, and in particular, as damage to buoyancy bodies, which is a vulnerability of floating solar power generation facilities, has been highlighted as a cause of eco-friendly(EVA) buoyancy bodies to improve buoyancy excellence was also achieved in various aspects such as resilience, environmental friendliness, maintenance, and durability.

본 연구는 스마트분전반 MG(;Micro-Grid) 구성의 중심축으로 모듈형 하이브리드 발전원과 DC 버스를 통하여 링크를 갖으며 표준소켓을 사용하여 불법연결을 감지 차단하는 기능을 부여하고, 전력 계통의 안정화를 달성함을 목적으로 한다. 전력변환장치, 스마트분전반, 통합제어시스템의 개발과 효율 적인 수요관리가 필요하며, MG 전체시스템과의 호환성이 절실하다. 이는 공통 전력 연결 규약으로 안 전하고 누구나 연결을 쉽게 할 수 있는 하이브리드발전시스템으로 데이터 관리가 용이해지고 다양한 제조사의 시스템 확대설치에 대한 대비가 가능하다.

This study is the central axis of the MG (Micro-Grid) configuration and it has the link through the modular hybrid power source and the DC bus, and it provides the function to detect and block the illegal connection by using the standard socket, And to achieve stabilization. Development of power conversion device, smart distribution panel, integrated control system and efficient demand management are required, and compatibility with MG whole system is urgent. This is a hybrid power generation system that is safe with a common power connection protocol and can be easily connected to anyone. This makes it easy to manage data and prepare for expansion of various manufacturers' systems.

이 연구는 20KW이하 태양광발전시스템에 대한 구성부품별 위험성에 대하여 고장모드영향분석과중요도 등을 활용하여 위험우선순위를 결정하는 자료를 도출하는데 그 목적이 있다. 중요도 분석결과 중요도는 총 4개의 고장모드로 인버터의 Fails to transfer(521), 필터(C)의 Shorted(541), 통신의Shorted(551)와 Function Failure(552)로 나타났다. 중요도를 통한 위험우선순위가 높은 부품은 통신과관련되어 있었다. 인버터의 Degraded output를 일으키는 주요 부품은 IGBT이다. IGBT는 24시간 풀가동하며 성능이 저하되었을 때 이를 감지하기도 어렵다. 따라서 내구성 및 수명이 높은 IGBT의 선택이 필요하다. 태양광발전시스템의 경우 모든 설비들이 통신과 연계되어 있어서 통신과 연결되는다량의 커넥터와 해당 커넥터의 기능적 고장에서 초래됨을 확인하였다. 또한 통신의 경우 RS-422의4선이 사용되고 있고 외부잡음에 영향을 많이 받는다. 따라서 2선 방식과 외부잡음에 강한 RS-485를사용하여 기능적 고장에 대한 신뢰성을 확보해야 할 것으로 판단이 된다. 본 데이터는 태양광발전시스템의 유지 및 보수를 위한 기초자료로 활용가능하다.

This study is intended to obtain the data for determining the risk priority by using criticality, analysis of failure mode effects, and the like regarding the risk involving component parts of photovoltaic power system with capacity of 20kw or below. According to the results of criticality analysis, a total of 4 failure modes are reported such as fails to transfer of an inverter (521), shorted (541) filter (C), shorted (551) communication, and function failure (552). Based on criticality, component parts having a high risk priority are related to communication. In the case of photovoltaic power system, as all of its devices are connected to communication, it is found that failures are caused by the failure of multiple connectors attached to communication. This data can be utilized as baseline data for the maintenance of photovoltaic power system.

In this paper, characteristics of a tidal current power generation system are analysis using power hardware-in-the-loop simulation (PHILS). A 10 kW motor generator set is connected to the real grid through a fabricated 10 kW back to back converter. A power control scheme is applied to the back to back converter. A 2 MW class tidal current turbine is modeled in real time digital simulator (RTDS). Generating voltage and current from the 10 kW PMSG is applied to a 2 MW class tidal current turbine in the RTDS using PHILS. The PHILS results depict the rotation speed, power coefficient, pitch angle, tip-speed ratio, and output power of tidal current turbine. The PHILS results in this paper can contribute to the increasing reliability and stability of the tidal current turbines connected to the grid using PHILS.

최근 화석연료의 과도한 소비로 인해 다양한 환경문제가 발생하고 있으며, 이에 대한 대안으로 신재생에너지의 중요성과 그에 대한 시설의 수요가 꾸준히 증가하고 있다. 이러한 수요를 만족하기 위하여, 다수의 태양광발전 구조물들이 건설, 계획되고 있다. 그러나 대부분의 태양광발전 시설들은 육지에 시공되고 있기 때문에 토지 이용에 따른 건설비의 증가와 토지 개간에 의한 추가적인 환경문제 등이 발생하고 있다. 이러한 문제점을 해결하기 위하여 최근 국내에서는 FRP를 활용한 수상 부유식 태양광발전 구조물에 대한 연구를 지속적으로 수행하고 있다. FRP는 높은 강도와 내부식성 및 작은 단위중량 등의 장점을 가지고 있기 때문에 최근 토목분야에서 각광받고 있으며, 이러한 재료적 특성은 자중에 따라 부력체의 크기가 결정되는 수상 구조물에 특히 유용하다. 이 연구에서는 수상 부유식 태양광발전 구조물과 구조물을 구성하는 SMC FRP 수직재의 구조적 성능을 평가하기 위한 해석적, 실험적 연구를 수행하였다. 수상 부유식 태양광발전 구조물은 유한요소해석을 통해 정적거동을 평가하고, 실험을 통해 동적거동을 평가하였다. 또한 SMC FRP 수직재는 유한요소해석을 통해 구조안전성 및 좌굴안정성을 평가하였으며, 실험을 통해 압축 및 인발 하중에 대한 구조적 거동 특성을 검토하였다. 검토 결과 펄트루젼 FRP (pultruded FRP)와 SMC (Sheet Modoling Compound) FRP로 구성된 구조시스템은 외부하중에 대한 안전성을 확보하고 있음을 확인하였다.

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

발전제어시스템의 보안 취약점 개선을 위한 선행 연구의 한계점을 분석하고 그 대안으로 사이버 보안 정보공유모델을 제안하였다. 발전제어시스템의 운영 특성을 파악하고 사이버 보안 정보공유 개념과 정책, 실제 구현사례들을 분석하여 발전제어시스템에 효과적으로 적용할 수 있는 정책과 기술방안을 제시하고 모델평가를 시행하였다.

The limitations of previous research on improving security vulnerabilities in power generation control systems were analyzed, and as an alternative, a cyber security information sharing model is proposed. Understanding the operational characteristics of power generation control systems, we examined the concepts and policies of cyber security information sharing, analyzing practical implementation cases. We presented effective policies and technological approaches that can be applied to power generation control systems, and their efficacy was verified through a model evaluation to validate their impact.

우리나라에서 현재 타 에너지원에 적용하고 있는 발전차액지원(FIT) 기준가격과 국외 사례의 기준가격을대상으로 실증 규모와 상업적 규모의 국내 인공 저류층 생성 지열발전에 대한 경제성을 분석하였다. 그리고 향후신재생에너지 발전의무비율할당(RPS) 제도의 시행을 고려하여 발전소 수명 기간 동안의 균등화 전력비용(LCOE)로예상 전력가격을 제시하였다. 분석결과 깊이 5 km의 생산정 2개와 주입정 1개의 실증(pilot) 규모 지열발전시스템에서 단위 발전비용은 198.5원/kWh 이며 발전규모는 3.60 MW가 가능하고 현재 시행되고 있는 연료전지(기타 연료이용)와 태양광(3 MW 이상)의 발전차액지원 기준가격과 독일의 지열발전 기준가격하에서도 경제성을 확보하는 것으로 나타났다. 그리고 생산정 6개와 주입정 4개의 상업규모 전력 생산 시 인공저류층 생성 효율에 따라 101.5-370.1원/MWh의 단위 발전비용으로 5.40-27.00 MW의 지열발전이 가능할 것으로 나타났다. 그리고 인공저류층 생성 효율이우수(공당 지열수 생산량 60 kg/sec) 이상인 경우 현재 국내 타에너지 및 외국 지열발전 기준가격에도 경제성을가진다. 하지만 민간이 수행하는 경우를 고려한 15%의 수익률을 보장할 경우, 지열발전에 대해 현재 태양광 이상의발전차액지원가격이 요구되었다. 30년 기간 이상의 신재생에너지 발전의무비율할당이 시행되는 경우, 앞서 제시한지열발전 용량과 단위 발전비용이 해당 발전에 대한 의무비율설정과 단위 전력가격에 대한 기준이 될 수 있다.

: We analyzed the economic feasibility of an enhanced geothermal system (EGS) for generating electric power on both pilot and commercial levels in Korea, under domestic feed-in tariffs (FITs) on other renewable energy sources and an international FIT on EGS. Considering the future imposition of a renewable portfolio standard (RPS)in Korea, we estimated the price of the geothermally generated electricity certificate by the levelized cost of electricity (LCOE), the unit power generation cost. A pilot-scale EGS with two production wells and one injection well of 5km depth was profitable in all assumed cases of ongoing FITs on fuel cells and solar cells in Korea and on EGS in Germany. We showed the pilot power plant’s size of 3.60 MW is possible with a 198.5 USD/MWh unit power generation cost in a 5% internal rate of return (IRR). The results of commercial-scale EGS were given for 5.40-27.00MW plant sizes and 101.5-370.1 USD/MWh unit costs in various reservoir efficiencies. Above high reservoir efficiency of 60 kg/sec flow rate each production well, commercial EGS would be feasible under domestic and German FITs but, by increasing the IRR to 15%, the FIT standard electricity price should be set over that of Korea’s present solar cell FIT. Before implementing a RPS, these presented electricity generation capacities and LCOEs could be considered to set the standard certificate and the electricity certificate price of geothermal electricity for more than 30 years.

In this paper, a tidal power conversion system (PCS) using seawater level differences was presented.. To verify the presented PCS, an actual lab-scale tidal power generation system was constructed. The operation of the lab-scale PCS was first modeled mathematically and was analyzed through dynamic simulation and experimental tests.

Numerical simulation has been carried out to analyze seawater flow characteristics for shroud geometry variations with tidal current generation turbine. Seawater flow field characteristics in the turbine system are largely influenced by the shroud geometry. The vortex flow area in the diffuser part of the shroud gradually grows with the increase of shroud angle, but its recirculation velocity gets smaller. The centerline velocity of shroud increases with the length of cylinder part when diffuser part length and angle are constant(2.5m, 0.733rad) for the cylinder-diffuser type shroud system. Seawater velocity on the tip of turbine blade is pretty high, and as radial distance increases from the turbine axis, there is more gap between the fluid velocity isolines. These results in this study will be applicable for optimal design of tidal current generation system.

최근 고층건물에 대한 수요가 급증하고 있다. 이러한 고층건물은 에너지를 많이 소비하기 때문에 고층 건물에서의 에너지 절약은 매우 중요한 문제이다. 고층건물에 신재생에너지를 적용하기 위한 다양한 기술들이 연구되고 있다. 최근 풍력발전을 건축물에 적용하여 풍력발전과 건설기술을 통합하는 건축물 통합형 풍력발전(building integrated wind power, biwp)이 다양하게 시도되고 있다. 고층건물의 최상부에 풍력발전시스템을 구축하기 위하여 일정한 개구부의 설치가 필수적이다. 개구부의 다양한 형태별 풍속변화에 대해서 알아보았다. 본 논문에서는 고층건물의 최상층에 풍력발전기를 설치를 위한 개구부의 형태를 직사각형, 원형, 마름모 3개의 형태로 하였다. 개구부의 바람이 유입되는 유입구와 바람이 흘러가는 유출구의 면적변화에 따른 풍속실험을 실시하였다. 실험결과 개구부의 형태에 따라 내부의 기류형태가 다르게 분포하였다. 마름모 개구부 형태가 가장 효율적인 기류분포를 하고 있었다.

In recent years, the demands of high-rise buildings have increased considerably. Since these buildings consume much energy, it is an important issue to save energy in the buildings. A variety of technologies have been studied to apply new and renewal energy to high-rise buildings. The integration of wind power generation and building technologies into building-integrated wind power (BIWP) has been attempted in various ways in recent years. It is essential to install the right type of opening in order to create a wind power generation system at the highest part of a high-rise building; thus, changes in wind velocity through various types of openings have been studied. In this paper, an opening installed for a wind power generator at the highest floor of a high-rise building was set to three shapes: a rectangle, a circle, and a rhombus. A wind velocity test was conducted according to changes in the areas of the wind inlet and wind outlet at the opening. The test results showed that the distribution of the inner air current shape differed according to the shape of the opening. A rhombus opening shape showed the most efficient air current distribution.

Numerical analysis has been carried out to investigate the characteristics of seawater flow fields and turbine output in a compact double current tidal power generation system for various level differences. There are growing concerns for the development of efficient tidal power generation which is stable and less affected by environmental circumstances as ocean energy. Especially the flow field characteristics in the compact tidal power generation system have a large influence on the system power generation performance. Flow velocity, pressure, and streamline distributions are compared including vertical type turbine out, and it can be predicted that seawater is accelerated by vortex flow in front of the turbine and there is severe turbine output variation due to the water level difference with pressure difference. These results can be applied as basic data for the effective development of compact tidal power generation system.

The most serious field of wasting energy consumption is energy used in buildings. During last 10years, The 1st energy consumption has grown rapidly so that we became the world 10th country consuming energy. The energy overseas dependence of our country which doesn't have enough natural resources has been raised from 87.9% in 1990 to 97.7% in 2004. The usage of fossil fuel meets the limit point. Serious change in global environment due to the usage of fossil fuel makes us focus into infinite pure resources and renewable energy. In this paper, we study through analysis of economic evaluation of this system for basic peculiar technological securement that is fit in korean actual circumstance.

In this study, we reviewed the technical standards for the energy performance evaluation method of small wind power systems installed in buildings and analyzed the energy performance evaluation by the default values proposed in the standards. The wind speed distribution in major cities in Korea has a shape parameter less than 2, indicating that the Rayleigh distribution has a large error for predicting annual energy production (AEP). It is proposed that the AEP calculation be included in the building energy efficiency rating certification program by taking the shape and scale parameters of the Weibull distribution as input values.

현재 국내의 대형 인프라시설물의 유지관리를 위해 생애주기비용분석 방법을 도입하고 있다. 그러나 시설물의 위치 및 주변환경 등의 조건을 반영한 유지관리 모델을 적용하는 사례가 많지 않다. 적절한 유지관리 전략을 수립하기 위해서는 시설물의 환경조건을 반영한 비용예측, 열화모델, 불확실성을 반영한 의사결정모델이 수립되어야 한다. 본 연구에서는 발전구조물에 적용되는 도장 사양을 대상으로 유지관리 방법과 판단기준에 따라 사용자의 의사결정에 따른 장기적인 비용 계획 및 관리를 할 수 있는 경제성 분석 모델을 개발하였다. 경제성 분석 모델의 적용을 위하여 도장열화실험을 통하여 도장의 성능을 평가하였으며, 제안 경제성 분석 모델에 적용하여 각각의 적용도장 사양(우레탄, 폴리실록산, 불소)에 따른 경제성 분석결과를 확인하였다. 본 연구에서는 도장의 성능보다 보수 주기의 선정과 개발 모델을 적용한 평가 방법을 제시한 결과로 도장에 국한되지 않더라도 유지관리 방안 수립 시 보수 주기 등을 위한 기초적인 자료로 활용을 기대할 수 있을 것으로 판단된다.

Currently, life-cycle cost analysis methods are introduced to maintain large infrastructure facilities in Korea. However, there are not many cases in which maintenance models are applied that reflect conditions such as the location of a facility and its surroundings. In order to establish an appropriate maintenance strategy, a cost prediction, deterioration model, and a decision model reflecting uncertainty should be established. In this study, an economic analysis model was developed for long-term cost planning and management based on user decisions based on maintenance methods and judgment criteria for painting specifications applied to power generation structures. The performance of the paintwork was assessed through the paint deterioration test for the application of the economic analysis model, and the results of the economic analysis according to the applied paint specifications (Urethan, polysiloxane, fluorine) were verified by applying the proposed economic analysis model. In this study, it is believed that the selection of the repair cycle and evaluation methods applied with the development model rather than the performance of the painting can be expected to be used as basic data for the maintenance cycle, even if it is not limited to the painting.

Seawater flow and turbine torque in a lab-scale tidal power generation system have been analyzed with CFD method. Its power generation is largely influenced by hydraulic flow characteristics of pressure variation and mechanical turbine torque in the system caused by vertical flow field including tangential rotation. Pressure drop through the turbine was gradually increased with flow rate by seawater level difference, and it depends on the turbine blade and system geometry. And curl was severely varied along the flow direction with more than about 8 times increase through the flow system. There was also turbine torque change with pressure inlet due to the water level. Those predicted results can be widely used as basic concept design data for efficient tidal power generation system development.