• Title/Summary/Keyword: Micro-grid

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Communication Architecture of the IEC 61850-based Micro Grid System

  • Yoo, Byong-Kwan;Yang, Seung-Ho;Yang, Hyo-Sik;Kim, Won-Yong;Jeong, Yu-Seok;Han, Byung-Moon;Jang, Kwang-Soo
    • Journal of Electrical Engineering and Technology
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    • v.6 no.5
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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.

A Study on the Effective Downscaling Methodology for Design of a Micro Smart Grid Simulator

  • Ko, Yun-Seok
    • Journal of Electrical Engineering and Technology
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    • v.13 no.4
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    • pp.1425-1437
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    • 2018
  • In this paper, a methodology was proposed to reduce the electrical level and spatial size of the smart grid with distributed generations (DGs) to a scale in which the electrical phenomena and control strategies for disturbances on the smart grid could be safely and freely experimented and observed. Based on the design methodology, a micro smart grid simulator with a substation transformer capacity of 190VA, voltage level of 19V, maximum breaking current of 20A and size of $2{\times}2m^2$ was designed by reducing the substation transformer capacity of 45MVA, voltage level of 23kV and area of $2{\times}2km^2$ of the smart grid to over one thousandth, and also reducing the maximum breaking current of 12kA of the smart grid to 1/600. It was verified that the proposed design methodology and designed micro smart grid simulator were very effective by identifying how all of the fault currents are limited to within the maximum breaking current of 20A, and by confirming that the maximum error between the fault currents obtained from the fault analysis method and the simulation method is within 1.8% through the EMTP-RV simulation results to the micro smart grid simulator model.

The Study on Micro-Grid Energy Management System(EMS) Integration in Ulleungdo (울릉도 Micro-Grid EMS(Energy Management System) 구축에 관한 연구)

  • Park, Min-Su;Chun, Yeong-Han
    • Proceedings of the KIEE Conference
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    • 2011.07a
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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.

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A Study on the Transient Operation Algorithm in Micro-grid based on CVCF Inverter (CVCF 인버터 기반의 Micro-grid에 있어서 과도상태 운용알고리즘에 관한 연구)

  • Lee, Hu-Dong;Choi, Sung-Sik;Nam, Yang-Hyun;Son, Joon-Ho;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.526-535
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    • 2018
  • Recently, in order to reduce the $CO_2$ emission in the island area, countermeasures to operate power system in a stable manner are being researched due to decrease of the operation rate in diesel generators and the increase of renewable energy sources. The phenomenon of energy sinking can be occurred if the output of renewable energy sources is larger than customer loads. Voltage of CVCF(constant voltage & constant frequency) battery could be increased rapidly according to the condition of SOC(state of charge) and blackout could be occurred due to shut-down of CVCF inverter, at carbon free island micro-grid based on the CVCF inverter. In order to overcome these problems, this paper proposes a transient operation algorithm in CVCF based micro-grid which in advance prevents shut-down of CVCF inverter during the energy sinking. And also this paper proposes the modeling of micro-grid including CVCF inverter, PV system, customer load using PSCAD/EMTDC S/W. From the results of micro-grid modeling based on the proposed algorithm, it is confirmed that CVCF based micro-grid can properly prevent shut-down of CVCF inverter according to SOC and battery voltage of CVCF inverter when energy sinking is occurred.

A Stable Operation Strategy in Micro-grid Systems without Diesel Generators

  • Choi, Sung-Sik;Kang, Min-Kwan;Lee, Hu-Dong;Nam, Yang-Hyun;Rho, Dae-Seok
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.114-123
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    • 2018
  • Recently, as one of the countermeasures to reduce carbon dioxide($CO_2$) for global warming problems, operation methods in micro-grid systems replacing diesel generator with renewable energy sources including wind power(WP) and photovoltaic(PV) system have been studied and presented in energetic manners. However, it is reported that some operation problems in micro-grid systems without diesel generator for carbon-free island are being occurred when large scaled WP systems are at start-up. To overcome these problems, this paper proposes an operation strategy in micro-grid systems by adapting control devices such as CVCF(constant voltage constant frequency) ESS(energy storage system) for constant frequency and voltage regulation, load control ESS for balancing demand and supply and SVC(static-var compensator) for reactive power compensation. From the simulation results based on the various operation scenarios, it is confirmed that the proposed operation strategy in micro-grid systems without diesel generators is a useful tool to perform a stable operation in micro-grid systems without diesel generator and also make a contribution to reduce carbon dioxide in micro-grid systems.

Operational Analysis of DC Micro-grid using PSCAD/EMTDC Software (PSCAD/EMTDC를 이용한 DC Micro-grid의 동작 분석)

  • Lee, Ji-Heon;Kwon, Ki-Hyun;Han, Byung-Moon
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.446_447
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    • 2009
  • This paper describes operational analysis results of the DC micro-grid using detailed model of distributed generation. Detailed model of wind power generation, photo-voltaic generation, fuel-cell generation was implemented with the user-defined model of PSCAD/EMTDC software that is coded with C-language. Various simulation results confirm that the DC micro-grid can operate without any problem in both the interconnected mode and the islanded mode. The operation analysis result confirms that the DC micro-grid make it feasible to provide power to the load stably.

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Economic Feasibility of MicroGrid on the Environmental Cost and Operation Type (환경비용 및 운용방식에 따른 MicroGrid 경제성 분석)

  • Park, Jung-Sung;Shin, Hye-Kyeong;Lee, Duck-Su;Choi, In-Sun;Choi, Young-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.10
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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.

Image Analysis of Micro Lesions According to Grid Frequency After Removal of Moire Artifact (Moire artifact 제거 후 그리드 주파수에 따른 미세병변의 영상분석)

  • Lee, Sang-Ho;Kim, Gyoo-Hyung;Yang, Oh-Nam
    • Journal of radiological science and technology
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    • v.41 no.5
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    • pp.463-469
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    • 2018
  • Morphological information such as shape and margin of micro lesion is important information for diagnosis of disease in clinical imaging. In this study, we investigated the morphological changes of the micro lesions by comparing the contrast and area in grid suppressed DR images according to grid frequency. In the profile analysis of the image, the mass showed an average intensity variation of 8.6 ~ 72.4 after suppression, The higher the grid frequency, the more the contrast was increased. However, in the images obtained using 103 lp / inch, which is a grid frequency less than the sampling frequency, the contrast of the mass in the vertical direction decreased after suppression. In the binary image, the area change of the mass was also large. As a result, the shape, size, and margin of the mass changed. In the case of very small calcification, the higher the grid frequency is the larger the change in contrast, so that a clear image can be obtained in the post-suppression image. However, we could confirm that the margin of the lesion was blurred and the lesion was lost in some of the images using the 103 lp / inch grid. The higher the frequency of the grid, The change of the contrast of fiber occurred largely and clear boundary was confirmed. The decrease of the number of pixels was small and morphological change was small. In conclusion, when using a grid frequency that is not suitable for the sample frequency, morphological changes or lesion loss of micro lesions in the post- suppression image may give the possibility of misdiagnosis in diagnosis and differentiation of the image.

Energy Management of a Grid-connected High Power Energy Recovery Battery Testing System

  • Zhang, Ke;Long, Bo;Yoo, Cheol-Jung;Noh, Hye-Min;Chang, Young-Won
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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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.

DC Micro-Grid Operational Analysis with a Detailed Simulation Model for Distributed Generation

  • Lee, Ji-Heon;Kim, Hyun-Jun;Han, Byung-Moon;Jeong, Yu-Seok;Yang, Hyo-Sik;Cha, Han-Ju
    • Journal of Power Electronics
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    • v.11 no.3
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    • pp.350-359
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    • 2011
  • This paper describes the operational analysis results of a DC micro-grid using a detailed model of distributed generation. A detailed model of wind power generation, photo-voltaic generation and fuel cell generation was implemented with an userdefined model created with PSCAD/EMTDC software and coded in C-language. The operational analysis was carried out using PSCAD/EMTDC software, in which the power circuit is implemented by a built-in model and the controller is modeled by an user-defined model that is also coded in C-language. Various simulation results confirm that a DC micro-grid can operate without any problems in both the grid-tied mode and in the islanded mode. The operational analysis results confirm that the DC micro-grid makes it feasible to provide power to the load stably. It can also be utilized to develop an actual system design.