• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.605-612
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• 2011

As the power grids are integrated into one big umbrella called a "smart grid," communication protocol plays a key role in successful operations. The successful deployment of smart grid interoperability is a major hurdle that must be overcome. The micro grid, a small power system that distributes energy resource, is operated in diverse regions. Different vendors use different communication protocols in the operation of the micro grid. Recently, the IEC 61850 has been legislated to solve the interoperability problems in power utility automation. The present paper presents a micro grid system based on the IEC 61850 protocol. It consists of a micro grid monitoring system, a protocol converter that transforms serial data to IEC 61850 data, and distributed energy resource controllers for diverse DER nodes. A developed communication gateway can be deployed for DER controllers with serial links to exchange data with IEC 61850-based devices. The gateway can be extended to IEC 61850-based distribution automation systems, substation automation systems, or SCADA.

• 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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• 제57권10호
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• pp.1738-1743
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• 2008

Environmental issue is one of the key factors to industry area using fossil fuels, because it accelerates the global warming. So it is supposed to reduce greenhouse gases around the developed nations of the world at times go. This issue is especially for the power industry. Under this background, MicroGrid system that consists of Distributed Energy Resources (DER) system, such as natural power system (wind, solar) and fuel-cell, co-generation, also known as CHP (Combined heat and power), has been developed greatly during the last 10 years. This paper adopts optimal model using GAMS to develop methods for conducting an integrated assessment of MicroGrid system.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1072-1079
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• 2014

This paper introduces a coordinated droop control for the stand-alone DC micro-grid, which is composed of photo-voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid.

• 전기학회논문지
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• 제64권2호
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• pp.228-231
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• 2015

In power system research fields, one of current key issues is the construction and commercialization of micro grid site which is called green island, carbon zero island, energy independent island, building micro grid, etc. and various affiliated technologies have been being vigorously developed to realize. In addition, various researches about electric vehicles (EVs) are in progress and it is expected to penetrate rapidly with the next a few years. Some new load models should be developed integrating with electric vehicle loads because the EVs' deployment could cause the change of load composition rate on power system planning and operations. EVs are also resources for micro grid as well as distributed generation and demand response so that various supply and demand side resources should be considered for micro grid researches. In this paper, the load composition rate of residential sectors is prospected considering the deployment of EVs and the resource configuration of micro grid is optimized based on net present cost. In the optimization, the load patten of case studies includes EV's charging characteristics and various cases are simulated comparing micro grid environment and normal condition. HOMER is used to compare various cases and economic effects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.304-305
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• 2011

이산화탄소의 배출로 인한 지구온난화와 화석연료의 고갈로 인한 에너지난은 신재생 에너지원의 필요성을 증가시켰다. 현재 국내에서는 디젤 발전기로 전력을 공급하는 울릉도 시스템을 신재생 에너지원을 계통에 연계시키는 울릉도 녹색 사업이 진행 중에 있다. 하지만 울릉도는 육지와의 거리가 멀어 계통 연계의 어렵고 신재생 에너지원의 출력 변동성으로 인한 계통운영에 어려움이 예상된다. 울릉도의 안정적인 전력 공급을 위해 Micro-Grid EMS 구축이 요구되는 상황이며 본 논문에서는 Micro-Grid EMS 구축을 위한 방안 및 방향성을 제시하고자 한다.

• 전기학회논문지
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• 제66권3호
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• pp.486-492
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• 2017

In recent years, renewable energy sources have been mentioned as solution to environmental regulation and energy supply-demand. Energy storage systems are needed to mitigate the intermittent output characteristics of renewable energy sources and to operate micro grid efficiently using renewable energy generation systems. However, despite the necessity of energy storage system, this cannot secure the economical efficiency of the energy storage system by high initial cost. In this paper, a micro grid is constructed to supply electric power to industrial customers by using solar power generation system and energy storage system among renewable energy generation power sources and operated to improve energy independence. In the case study, we use photovoltaic system which is representative renewable energy generation system. Unlike conventional photovoltaic system, this system uses floating photovoltaic system with the advantage of having high output and no land area limitations. It is operated for the purpose of improving energy independence in the micro grid. In order to secure economical efficiency, the energy storage system operates a micro grid with a minimum capacity. Finally, this paper calculates the appropriate subsidy for the energy storage capacity.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.839-847
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• 2016

Energy recovery battery testing systems (ERBTS) have been widely used in battery manufactures. All the ERBTS are connected in parallel which forms a special and complicated micro-grid system, which has the shortcomings of low energy recovery efficiency, complex grid-connected control algorithms issues for islanded detection, and complicated power circuit topology issues. To solve those shortcomings, a DC micro-grid system is proposed, the released testing energy has the priority to be reutilized between various testing system within the local grid, Compared to conventional scheme, the proposed system has the merits of a simplified power circuit topology, no needs for synchronous control, and much higher testing efficiency. The testing energy can be cycle-used inside the local micro-grid. The additional energy can be recovered to AC-grid. Numerous experimental comparison results between conventional and proposed scheme are provided to demonstrate the validity and effectiveness of the proposed technique.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.520-521
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• 2008

This paper deals with simulation model of the micro-grid system based on the real power system and applying PV generation system to micro-grid system. PSCAD/EMTDC simulation model is developed for use in studying the effect of the dynamics of PV generation to the micro-grid system. Simulation results show that the addition of the PV system improves the voltage profile of the area. Case studies also show that power quality at the load side is improved via voltage compensation at the load bus.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1328-1334
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• 2015

A new system for evaluating the voltage management errors of distribution equipment is presented in this paper. The main concept of the new system is to use real distribution live-line voltage to evaluate and correct the voltage measurement data from distribution equipment. This new approach is suitable for a new Distribution Management System (DMS) which has been developed for a distribution power system due to the connection of distributed generation growth. The data from distribution equipment that is installed at distribution lines must be accurate for the performance of the DMS. The proposed system is expected to provide a solution for voltage measurement accuracy assessment for the reliable and efficient operation of the DMS. An experimental study on actual distribution equipment verifies that this voltage measurement accuracy assessment system can assess and calibrate the voltage measurement data from distribution equipment installed at the distribution line.