• 동력기계공학회지
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• 제13권6호
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• pp.95-101
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• 2009

The generator for gas turbine power generation consists of the rotor which generates magnetic field, the winding coil which is the path for the field current and the wedge and retaining ring which prevents the radial movement of the coil. Relatively severe deformation was observed at the coil end section during the inspection of the generator for peaking-load operation, and the thermal-electricity and the centrifugal force were evaluated by the simple modeling of the windings to find the cause. But the simulation stress was not sufficient to induce the coil plastic deformation. The analysis result seems to be applicable to the base-load generators which runs continuously without shut down up to a year, but there had been more deformation than simulated for the generator which is started up and shut down frequently. The cause of the coil deformation was the restriction of the expansion and shrinkage. The restriction occurs when the winding coil shrinks, and the stress overwhelms the yield stress and cause the plastic deformation. The deformation is accumulated during the start-ups and shut-downs and the thermal growth occurs. The factors which induce the coil restriction during the expansion and shrinkage should be reduced to prevent the unallowable deformation. The resolutions are cutting off the field current earlier during the generator shut-down, modifying the coil end section to remove the stress concentration and making the insulation plate inserted between the coil end section and the retaining ring have the constant thickness.

• 한국항행학회논문지
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• 제19권5호
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• pp.433-439
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• 2015

최근 컴퓨터, 전기, 전자, 통신, 반도체 장비 등의 전기적 외란에 민감한 부하 설비의 사용이 증가함에 따라 전력 품질에 대한 관심이 높아지고 있다. 더 나아가서는 정밀 부하 장비들에 가장 빈번하게 발생하는 순간 전압 강하는 전력 품질 향상을 위해 적정한 보상이 필요하게 된다. 이를 위해 전기 이중층 커패시터 (EDLC : electric double layer capacitor)를 사용한 순간전압강하 보상장치가 개발되어 적용되고 있다. 본 논문에서는 순간전압강하 보상장치 (DVR : dynamic voltage restorer)에 사용되는 전기 이중층 커패시터(EDLC)에 비해 동일 사이즈 대비 에너지 밀도가 높은 하이브리드 커패시터 (hybrid capacitor)를 적용하는 연구를 하였고, 또한, 유도등의 비상 전원으로써 10년 이상의 수명을 보증할 수 있는 제품으로 하이브리드 커패시터 (hybrid capacitor)의 적용 가능성을 확인하였다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1673-1681
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• 2015

A low dropout (LDO) regulator with a wide-bandwidth is proposed in this paper. The regulator features a Human Body Model (HBM) 8kV-class high robustness ElectroStatic Discharge (ESD) protection circuit, and two error amplifiers (one with low gain and wide bandwidth, and the other with high gain and narrow bandwidth). The dual error amplifiers are located within the feedback loop of the LDO regulator, and they selectively amplify the signal according to its ripples. The proposed LDO regulator is more efficient in its regulation process because of its selective amplification according to frequency and bandwidth. Furthermore, the proposed regulator has the same gain as a conventional LDO at 62 dB with a 130 kHz-wide bandwidth, which is approximately 3.5 times that of a conventional LDO. The proposed device presents a fast response with improved load and line regulation characteristics. In addition, to prevent an increase in the area of the circuit, a body-driven fabrication technique was used for the error amplifier and the pass transistor. The proposed LDO regulator has an input voltage range of 2.5 V to 4.5 V, and it provides a load current of 100 mA in an output voltage range of 1.2 V to 4.1 V. In addition, to prevent damage in the Integrated Circuit (IC) as a result of static electricity, the reliability of IC was improved by embedding a self-produced 8 kV-class (Chip level) ESD protection circuit of a P-substrate-Triggered Silicon Controlled Rectifier (PTSCR) type with high robustness characteristics.

• 전자공학회논문지
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• 제54권8호
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• pp.115-122
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• 2017

본 논문에서는 슬라이닥을 이용하는 새로운 역률보상시스템을 제안한다. 제안하는 역률보상시스템은 슬라이닥의 출력전압을 커패시터에 인가하여 역률을 보상하는 구조이다. 기존의 커패시터 뱅크 방법을 이용하는 역률보상시스템은 선택 가능한 커패시터 용량이 한정되어 있어 부하 상황에 따라 역률 보상 오차가 발생하지만, 제안 시스템은 커패시터 인가 전압을 슬라이닥을 이용하여 세밀하게 변화시킬 수 있어 변화하는 부하를 추종하여 오차 없이 역률을 100%까지 보상할 수 있다. 기존 시스템과 제안 시스템을 비교하여 제시하고, 제안 시스템의 역률 보상 성능이 우수함을 모의실험과 실험을 통해 확인한다. 제안 시스템을 수용가에 설치할 경우 역률 개선을 통한 전기료 감소, 선로손실 감소, 부하 용량 증대 효과가 기대된다. 특히 발전 사업가측에서는 역률 보상 성능의 향상으로 송전 여유 용량 확보와 발전량 절감이 가능하다.

• 전기전자학회논문지
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• 제22권3호
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• pp.733-737
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• 2018

본 논문에서는 신재생 발전원의 추가에 따라 계통에 미치는 영향에 관하여 서술하였다. 계통의 안정도 검토를 위해, PSS/E S/W을 이용하여 계통 해석을 수행하였다. 정상상태 조류 계산을 통한 선로 과부하 검토 및 고장 용량 해석을 통한 고장 전류초과여부 및 상정고장 해석을 통한 선로 과부하 여부를 확인하였다. 다이나믹 시뮬레이션을 통해 계통의 동적안정도를 확인하였다. 신재생 발전기 추가에 따른 계통 해석은 전력계통 신뢰도 및 전기품질 유지기준에 따라 해석을 수행하였다.

• 전기학회논문지
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• 제65권6호
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• pp.923-933
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• 2016

This paper proposes a new method for evaluating Effective Load Carrying Capability(ELCC) and capacity credit(C.C.) of power system including Wind Turbine Generator(WTG) combined with Battery Energy Storage System(BESS). WTG can only generate electricity power when the fuel(wind) is available. Because of fluctuation of wind speed, WTG generates intermittent power. In view point of reliability of power system, intermittent power of WTG is similar with probabilistic characteristics based on power on-off due to mechanical availability of conventional generator. Therefore, high penetration of WTG will occur difficulties in power operation. The high penetration of numerous and large capacity WTG can make risk to power system adequacy, quality and stability. Therefore, the penetration of WTG is limited in the world. In recent, it is expected that BESS installed at wind farms may smooth the wind power fluctuation. This study develops a new method to assess how much is penetration of WTG able to extended when Wind Turbine Generator(WTG) is combined with Battery Energy Storage System(BESS). In this paper, the assessment equation of capacity credit of WTG combined with BESS is formulated newly. The simulation program, is called GNRL_ESS, is developed in this study. This paper demonstrates a various case studies of ELCC and capacity credit(C.C.) of power system containing WTG combined with BESS using model system as similar as Jeju island power system. The case studies demonstrate that not only reasonable BESS capacity for a WTG but also permissible penetration percent of WTG combined with BESS and reasonable WTG capacity for a BESS can be decided.

• 한국가스학회지
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• 제18권2호
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• pp.28-34
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• 2014

일반적인 천연가스 정압기지에서는 압력제어밸브를 이용하여 고압으로 수송되는 천연가스를 감압하여 내보낸다. 이 과정에서 버려지는 폐압에너지는 터보팽창기를 도입하여 추가적인 전력생산이 가능하나 터보팽창기를 통과하는 유체에서는 감압에 의한 Joule Thompson 효과에 의하여 온도가 급격히 떨어져 파이프라인 외부에 동결을 일으키거나 파이프라인 내부에 메탄하이드레이트와 같은 고체 물질이 형성될 위험이 있다. 현재 터보팽창기를 채용한 천연가스 정압기지에서는 냉열발생에 따른 부작용을 방지하기 위하여 터보팽창기의 전단에 보일러를 설치하여 팽창 전 천연가스를 예열하고 있다. 용융탄산염연료전지와 같은 고온 연료전지는 천연가스를 연료로 사용할 수 있고 친환경적인 고온 배출가스를 방출하며 동시에 추가적인 전력을 생산하여 시스템의 효율을 높일 수 있다. 이 논문에서는 천연가스 정압기지에 용융탄산염연료전지와 터보팽창기를 설치하여 얻을 수 있는 열역학적 이득에 대해서 연구하였다. 연료전지를 기저부하로 사용함에 따라서 얻을 수 있는 이익에 대하여 분석하였다.

• Journal of Communications and Networks
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• 제14권6호
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• pp.662-671
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• 2012

Plug-in hybrid electric vehicles (PHEVs) will be widely used in future transportation systems to reduce oil fuel consumption. Therefore, the electrical energy demand will be increased due to the charging of a large number of vehicles. Without intelligent control strategies, the charging process can easily overload the electricity grid at peak hours. In this paper, we consider a smart charging and discharging process for multiple PHEVs in a building's garage to optimize the energy consumption profile of the building. We formulate a centralized optimization problem in which the building controller or planner aims to minimize the square Euclidean distance between the instantaneous energy demand and the average demand of the building by controlling the charging and discharging schedules of PHEVs (or 'users'). The PHEVs' batteries will be charged during low-demand periods and discharged during high-demand periods in order to reduce the peak load of the building. In a decentralized system, we design an energy cost-sharing model and apply a non-cooperative approach to formulate an energy charging and discharging scheduling game, in which the players are the users, their strategies are the battery charging and discharging schedules, and the utility function of each user is defined as the negative total energy payment to the building. Based on the game theory setup, we also propose a distributed algorithm in which each PHEV independently selects its best strategy to maximize the utility function. The PHEVs update the building planner with their energy charging and discharging schedules. We also show that the PHEV owners will have an incentive to participate in the energy charging and discharging game. Simulation results verify that the proposed distributed algorithm will minimize the peak load and the total energy cost simultaneously.

• 한국태양에너지학회 논문집
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• 제38권2호
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• pp.55-66
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• 2018

South Korea aims to shift the 20 percent of electricity supplement from the fossil fuel including the nuclear to renewable energy systems by 2030. In order to realize this agenda in the buildings, the plus energy house is necessary to increase the renewable energy supplement beyond the zero energy house. This paper suggested KePSH (KIER Energy-Plus Solar House) and energy performance of house and renewable energy systems was investigated. The KePSH has the target of generating 40% surplus energy than the conventional house energy consumption. The plus energy house is the house that generates surplus energy from the renewable energy sources than that consumes. In order to minimize the cooling and heating load of the house, the shape design and passive parameters design were conducted. Based on the experimental data of the plug load in the typical house, the total energy consumption of the house was estimated. This paper also suggested renewable energy sources integrated HVAC system using air-source heat pump system. Two cases of renewable energy system integration methods were suggested, and energy performance of the cases was investigated using TRNSYS 17 program. The results showed that the BIPV (building integrated photovoltaic) system (i.e., CASE 1) and BIPV and BIST system (i.e., CASE 2) shows 42% and 29% of plus energy rate, respectivey. Also, CASE 1 can generate 59% more surplus energy compared with the CASE 2 under the same installation area.

• 지질공학
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• 제16권4호
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• pp.351-357
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• 2006

상수원으로 사용하고 있는 주요 하천으로의 위해물질의 유입은 정수장에서의 고도기술을 요구하게 된다. 그러므로 산업폐수로부터 방류되는 이들 미량유해화학물질의 모니터링을 적절하게 하는 것은 위해도 저감 뿐 만 아니라 하천관리의 경제성도 증가시킬 수 있다. 본 연구를 통해 모니터링 한 여러 미량 유해화학물질 중에서 산업폐수의 방류수에서 검출된 오염물질 중 가장 주요한 항목은 Hexachlorobutadiene 였다. 그러나 반도체, 전기/전자 및 금속조립 산업폐수로 구성된 Group II에서는 모든 항목이 불검출로 나타났다. 따라서 향후 상수원 수질개선 및 보호를 하기 위해 모니터링 항목을 선정하는데 있어서는 해당 수계로 부하되는 물질들의 특성과 거동을 제대로 파악하기 위한 사전모니터링을 실시하여 시간, 노력 및 경제적인 손실을 최소화하여 효율적인 상수원관리를 해야 한다.