• 조명전기설비학회논문지
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• 제19권6호
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• pp.52-58
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• 2005

Micro-Grid의 개념은 CERTS(Consortium for Electric Reliability Technology Solutions)에 의해 제안된 새로운 분산 전원 망으로서 부하에 열과 수 $[KW]{\sim}1[MW]$ 사이의 전력을 함께 제공하는 Micro-Source에 의해 구성되어 있다. Micro-Source는 친환경적인 연료전지나 마이크로터빈 등을 에너지원으로 사용하며, 전력품질 제어를 위해 전압형 인버터를 채용하고 독립적인 유무효전력 제어가 가능한 새로운 개념의 분산전원이다. Micro-Source가 효율적으로 유효전력 및 무효전력을 전력시스템에 공급하기 위해서는 계통연계용 인덕터가 필요한데, 본 논문에서는 인덕터의 제어 범위와 각 변수의 한계를 함께 고려하고 전달 및 제어하고자 히는 유효 및 무효 전력의 범위에 의해 인덕터 용량을 결정하는 절차를 제안하였다.

• 전기학회논문지
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• 제58권1호
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• pp.35-41
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• 2009

This paper proposes a stand alone type single-phase fuel cells micro-source with a voltage sag compensator for compensating the ac output voltage variations (sag or swell) of micro-source. The proposed micro-source is consist of a PEM(polymer electrolyte membrane) fuel cells simulator, a full bridge de converter, a 60Hz PWM(pulse width modulation) VSI(voltage source inverter), and a voltage sag compensator. Voltage sag compensator is similar to the configuration of hybrid series active power filter, and it is directly connected to micro-source through the injection transformer. Compensation algorithm of a voltage sag compensator adopts a single phase p-q theory. Effectiveness of the proposed the system is verified by the PSIM(power electronics simulation tool) simulation in the steady state and transient state which the proposed system is able to simultaneously compensate the harmonic current and source voltage sag or swell.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.280-282
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• 2005

Micro-source units having power ratings in thousands of watts can provide even higher reliability and fuel efficiency than the conventional large scale units. These units are also clustered with loads creating micro-grid services to customer sites such as office buildings, industrial parks and homes. Micro-sources adopt voltage source inverter to ensure the power quality of sensitive loads. This paper deals with the connection of micro-sources into the system grid. Modeling and simulation of the grid connected micro-sources at the power frequency range are investigated. Simulation results show that the micro-grid system with two micro-sources has good dynamic characteristics.

• 조명전기설비학회논문지
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• 제21권7호
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• pp.46-53
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• 2007

Micro-Grid는 높은 전력품질을 제공하기 위해 독립적으로 유효 및 무효전력 제어가 가능한 연료전지와 마이크로터빈과 같이 친환경적이고 신뢰할 수 있는 전력원을 채용하는 Micro-Source들로 구성된다. 본 논문은 Micro-Grid시스템의 동특성 모델링과 안정도 해석의 기본적 해석 방법에 관하여 연구하였다. Micro-Source 인버터의 기본주파수 모델을 이용하여 Micro-Grid 시스템의 동특성 모델을 구성하였다. Micro-Grid 시스템의 선형화된 동특성 모델을 기초로 하여 안정도 해석을 수행하였다. 사례연구 결과로부터 Micro-Grid 시스템의 안정도에 영향을 미치는 파라미터를 식별하였다.

• 전기학회논문지
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• 제56권5호
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• pp.841-847
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• 2007

This paper deals with the micro-grid consisting of micro-sources which adopt voltage sourced inverters with independent real and reactive power control capability for providing premium power quality. This paper presents dynamic modeling and the stable operating range of the micro-grid system varying the parameters of the micro-sources. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system. Stability analysis is performed based on the linearized dynamic model of the micro-grid system. Case study results show the parameters affecting the stability of the micro-grid and the stable operating range of the micro-sources.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권8호
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• pp.419-422
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• 2001

This paper presents the principle and fabrication of a novel micro mass spectrometer and emission test of hot electron for ionization. A micro mass spectrometer consists of a micro ion source and a micro ion separator. The micro ion source consists of a hot filament and grid electrodes. Electrons emitted from a hot filament are to ionize some sample molecules. The ions are accelerated to an ion detector by an electric field. Mass can be analyzed by using the time of fight depending on the mass-to-charge ratio. The current of hot electron emission from the hot filament is measured for various input voltages.

• 조명전기설비학회논문지
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• 제20권3호
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• pp.12-19
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• 2006

마이크로소스는 1[kW]${\sim}$수[MW] 사이의 전력을 공급하고, 기존의 대규모 발전설비보다 높은 신뢰도와 에너지 효율을 가지는 고품질의 전력을 공급할 수 있다. 본 논문에서는 마이크로소스의 스위칭레벨 모델을 개발하였으며, 다수의 마이크로소스가 전력시스템과 연계되어 마이크로그리드를 형성할 경우의 특성에 대하여 연구하였다. 마이크로소스는 인버터의 효율을 극대화 할 수 있도록 공간벡터 펄스폭변조(Space Vector PWM, SVPWM) 기법을 채용하였으며, 마이크로소스의 제어시스템 파라미터 특성 및 마이크로소스 상호작용에 관하여 연구하였다. 마이크로소스는 PSCAD/EMTDC를 이용하여 구현하였으며 이를 이용해 마이크로그리드를 구성하여 시뮬레이션하였다. 사례 연구를 통하여 제안된 모델의 효용성을 확인하였다.

• 전기학회논문지
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• 제56권3호
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• pp.457-464
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• 2007

Micro-Grid comprising Micro-Sources supplying several $kW{\sim}MW$ power to local customers is environmentally friendly and reliable. This paper deals with the development of simulation models of Micro-Grid on the PSCAD/EMTDC platform for analyzing various aspects of the interaction of the Micro-Grid. The developed switching level model adopts the space vector PWM. Both switching level and power frequency Micro-Source models are developed, which shows that power frequency modeling is sufficient for analyzing the phenomena of interest. Control characteristics of the Micro-Sources with the parameter and load power variation are analyzed for power quality enhancement. The simulation results show that the developed models are effective for studying Micro-Grid.

• 전기학회논문지
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• 제58권1호
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• pp.42-48
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• 2009

Microgrid supplies loads with power interconnected grid. And it is defined a independent power system compounded micro sources over two devices which have enough capacity to operate independently, storage devices and loads. The energy sources of micro source have different dynamic characteristics corresponding to classes and application skills. However their transient responses are various from a few seconds to minutes. Therefore it is limitation for understanding operation characteristics of microsource modeling constant voltage source or constant current source. This paper shows that we designed EMTP/RV model of micro source which is microturbine based energy source. And we performed dynamic analysis of micro source corresponding to operation mode of microgrid.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.17-21
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• 2010

Currently miniaturized electron-optical columns find their way into electron beam lithography systems. For better lithography process, it is required to make smaller spot size and longer working distance. But, the micro-columns of the multi-beam lithography system suffer from chromatic and spherical aberration, even when the electron beam is exactly on the symmetric axis of the micro-column. The off-axis error of the electron emitting source is expected to become worse with increasing off-axis distance of the focusing spot. Especially the electron beams far from the system optical axis have a non-negligible asymmetric intensity distribution in the micro-column. In this paper, the effect of the off-axis e-beam source is analyzed. To analyze this effect is to introduce a micro-column model of which the e-beam emitting source is aligned with the center of the electron beam by shifting them perpendicular to the system optical axis. The presented solution can be used to analysis the performance of the multi-electron-beam system. The performance parameters, such as the working distances and the focusing position are obtained by the computational simulations as a function of the off-axis distance of the emitting source.