• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1989-1990
• /
• 2011

스마트그리드 즉, 미래 지능형 전력시스템이 추구하는 가장 큰 특징은 표준화 기반의 시스템간 상호운용성과 최신 기술을 이용한 자동화라고 할 수 있겠다. 그러므로 시스템간 상호 운용이 가능한 스마트그리드 시스템의 개발을 위해서는 요구분석부터 전반적인 시스템의 조건을 만족할 수 있도록 고려되어야 한다. 스마트그리드를 위한 전력시스템의 개발에 활용 될 수 있는 방법론으로는 'IEC 62559 IntelliGrid Methodology(IntelliGrid$^{SM}$, 이하 IntelliGrid 방법론)'이 있다. IntelliGrid 방법론은 IEC에 의하여 2007년에 채택된 전력에너지시스템 개발을 위한 방법론(IEC 62559, PAS(Publicly Available Specification))으로, EPRI의 'IntelliGrid 프로그램'의 산출물이다. IntelliGrid 방법론에 기반한 요구분석 방법론을 체계적인 스마트그리드 시스템 개발을 위한 요구분석 방안을 제시한 결과물로 평가할 수 있다. 본 논문에서는 IntelliGrid 방법론의 내용을 분석해 보고, AMI 개발을 위한 요구분석 방법론으로 'IntelliGrid 방법론'을 적용하는 방안 및 절차에 관하여 제시하고자 한다.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.161-162
• /
• 2015

최근 세계적으로 전력계통의 대륙 간 연계나 신재생에너지, 분산전원의 계통 연계를 위해 HVDC(High voltage Direct Current)에 대한 연구가 활발히 진행되고 있다. 대용량, 장거리 송전이 필요한 경우 HVAC에서의 전력손실과 송전거리의 한계를 극복하기 위하여 HVDC가 새로운 대안으로 떠오르고 있으며, LCC(Line commutated Converter)와 VSC(Voltage Source Converter)의 기술발전이 비약적으로 이뤄지고 있다. 특히, DC Grid화를 위해서 유럽에서는 해상풍력을 연계한 Windfarm을 DC Grid화 하는 프로젝트가 활발히 진행되고 있다. 이러한 신재생 에너지의 계통 연계를 위해서 DC Grid가 본격적으로 논의가 되고 있고 관련분야에서는 기술개발을 앞다퉈 진행하고 있는 상황이다. DC Grid 구현을 위해 VSC HVDC가 최근 주목받고 있으며, VSC로 연계된 DC Grid의 AC 계통과의 연계를 위해 가장 필요한 것이 바로 DC 차단기라고 할 수 있겠다. 본 논문에서는 DC Grid의 고장분석을 위한 기초연구로써 MMC(Modular Multilevel Converter) VSC를 기반으로 한 Point-to-Point HVDC Grid에서의 DC 고장에 대한 분석을 실시하였으며 그 특징을 분석하였다.

• Journal of Power Electronics
• /
• v.11 no.4
• /
• pp.561-567
• /
• 2011

This paper presents a high-efficiency power conditioning system (PCS) for grid-connected photovoltaic (PV) modules. The proposed PCS consists of a step-up DC-DC converter and a single-phase DC-AC inverter for the grid-connected PV modules. A soft-switching step-up DC-DC converter is proposed to generate a high DC-link voltage from the low PV module voltage with a high-efficiency. A DC-link voltage controller is presented for constant DC-link voltage regulation. A half-bridge inverter is used for the single-phase DC-AC inverter for grid connection. A grid current controller is suggested to supply PV electrical power to the power grid with a unity power factor. Experimental results are obtained from a 180 W grid-connected PV module system using the proposed PCS. The proposed PCS achieves a high power efficiency of 93.0 % with an unity power factor for a 60 Hz / 120 Vrms AC power grid.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.585-588
• /
• 2002

Grid provides integral ing system that enables to use distributed computing resource and services as adapts traditional infrastructures to overcome the distributed computing environments. But, computing today is moving away from a restriction of the desktop, becoming diffused into our surrounding and onto our personal digital devices. In such mobile computing environments, users expects to access resource and services at any time from anywhere in such Mobile-Grid computing. This expectation results security issues, since the computing environments is expanded. This paper describes the security challenges in Mobile-Grid computing, explaining why traditional security mechanism fail to meet the demands of these environments. This paper describes policy driven security mechanism enabled entity to use service and data in trust Mobile-Grid environments and a set of security service module that need to be realized in the Mobile-Grid security architecture presents a set of use pattern that show hew these modules can be used for billing service in a secure Mobile-Grid environments.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.2
• /
• pp.97-102
• /
• 2005

Because of the limited fossil resources and the need to avoid emissions and toxic waste the future energy supply will be based on a large portion of renewable energies: wind-, solar-, biomass- and geothermal energy. Focus is on the utilization of wind energy coming from onshore- and offshore-sites. Generating electricity from wind is state of the art and feeding large amounts of wind power into the electrical grid will create some additional problems. Suggestions concerning energy storage will be made and the problem of power quality is discussed.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.454-455
• /
• 2010

This paper surveys recent works in line impedance estimation. Inverters used in distribution system are often connected to the grid through LCL filter. Different methods are investigated for estimating the line impedance. Advantages and disadvantages with brief summary for each method are presented. Simulation results for a specified grid are shown for two main different methods and the results are compared with estimation error.

• Proceedings of the KIEE Conference
• /
• 2003.11a
• /
• pp.137-139
• /
• 2003

Micro-Sources arc emerging as a providing environmentally friendly and reliable and effective solution. Micro-Source converter DC voltage of prime mover to AC voltage using voltage source inverter for interjecting with AC grid system. This paper studies optimal series inductance size for interjecting with AC grid system.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.04a
• /
• pp.230-231
• /
• 2012

지능형 응용 개발 스튜디오의 어플리케이션 디자이너와 블록 에디터를 활용하면, 개발 언어에 대한 지식이 없거나 개발 경험이 없는 사람도 코드 작성 없이 간단히 Drag&Drop으로 기능을 개발 할 수 있다. 본 연구에서는 지능형 스튜디오 환경에서 간단한 온라인 게임을 시험적으로 제작하고 평가한다.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.522-532
• /
• 2017

In this study, we propose a fault analysis method for a power distribution grid with PCS-based DERs. We first explain the characteristics of a PCS-based DER. According to the characteristics, the DER is considered as a current-controlled voltage source, which produces varying voltages within a certain limit so that currents equal to given references flowing from the DER to the grid (currents controlled). So, we introduce the symmetrical equivalent models in the form of varying voltage source for fault analysis and then, construct a convex optimization problem to solve the fault problem associated with the equivalent models and grid conditions. Thus, the proposed method enables to perform a proper fault analysis considering the characteristics of the DER, which are currents controlled, voltage limited, and unity power factor achievement. To verify the validity of the proposed method, we perform computer simulations with the proposed method and with MATLAB Simulink, and the results are compared.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.173-174
• /
• 2016

This paper proposes a comparison of Voltage Oriented Control (VOC) and Direct Power Control (DPC) under command mode transition for PMSG Wind Turbines (WT). Based on a neutral point clamped three level back to back type Voltage Source Converter (VSC), proposed control scheme automatically control the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. Automatic command mode transition based on the dc-link voltage error provides a command mode changing between grid command and MPPT mode. It is confirmed through PLECS simulations in Matlab. Simulation result shows that proposed control scheme of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control scheme of MPPT with optimal torque control and VOC under a step response. The proposed control scheme makes it possible to provide a good dynamic performance for PMSG wind turbines in order to generate a high quality output power.