• Title/Summary/Keyword: Virtual Grid

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Self-Adaptive Smart Grid with Photovoltaics using AiTES (AiTES를 사용한 태양광 발전이 포함된 자가 적응적 스마트 그리드)

  • Park, Sung-sik;Park, Young-beom
    • Journal of Platform Technology
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    • v.6 no.3
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    • pp.38-46
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    • 2018
  • Smart Grid is an intelligent power grid for efficiently producing and consuming electricity through bi-directional communication between power producers and consumers. As renewable energy develops, the share of renewable energy in the smart grid is increasing. Renewable energy has a problem that it differs from existing power generation methods that can predict and control power generation because the power generation changes in real time. Applying a self-adaptative framework to the Smart Grid will enable efficient operation of the Smart Grid by adapting to the amount of renewable energy power generated in real time. In this paper, we assume that smart villages equipped with photovoltaic power generation facilities are installed, and apply the self-adaptative framework, AiTES, to show that smart grid can be efficiently operated through self adaptation framework.

A study on detecting trees and discriminating vertical building wall points from LIDAR point cloud (라이다 포인트 클라우드에서 수목 및 건물의 외부 수직벽 포인트의 인식과 제거에 관한 연구)

  • Han, Soo-Hee;Lee, Jeong-Ho;Yu, Ki-Un;Kim, Yong-Il
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2007.04a
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    • pp.179-182
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    • 2007
  • In this study, we proposed a way to detect trees using virtual grid and to discriminate vertical wall points from building tops based on effective segmentation of LIDAR point cloud utilizing scan line characteristics. Trees were detected by their surface roughness value calculated based on virtual grid and vertical building wall points were discriminated from building tops with one dimensional filtering of scan line during segmenting point cloud. In results, we could distinguish trees from buildings and bind virtical wall points to prevent them from faltly acting on point segmentation process.

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Novel Adaptive Virtual Impedance-based Droop Control for Parallel Operation of AC/DC Converter for DC Distribution (새로운 가상 임피던스 선정기법 기반의 적응 드룹을 이용한 직류배전용 AC/DC 컨버터의 병렬운전)

  • Lee, Yoon-Seong;Kang, Kyung-Min;Choi, Bong-Yeon;Kim, Mi Na;Lee, Hoon;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2020.08a
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    • pp.328-329
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    • 2020
  • The AC/DC converter, which connects the AC grid to the DC grid in the microgrid, is a critical component in power sharing and stable operation. Sometimes the AC/DC converters are connected in parallel to increase the transmission and reception capacity. When connected in parallel, circulating current is generated due to line impedance difference or sensor error. As a result of circulating current, there is deterioration and loss in particular PCS(Power Conversion System). In this paper, we propose droop control with novel adaptive virtual impedance for reducing circulating current. Feasibility of proposed algorithm is verified by PowerSIM simulation.

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USING VIRTUAL OBSERVATORY TOOLS FOR ASTRONOMICAL RESEARCH

  • KIM SANG CHUL;TAYLOR JOHN D.;PANTER BENJAMIN;SOHN SANGMO TONY;HEAVENS ALAN F.;MANN ROBERT G.
    • Journal of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.85-88
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    • 2005
  • Construction of the Virtual Observatory (VO) is a great concern to the astronomical community in the 21st century. We present an outline of the concept and necessity of the va and the current status of various VO projects including the 15 national ones and the International Virtual Observatory Alliance (IVOA). We summarize the possible science cases that could be solved by using the VO data/tools, real science cases which are the results of using current VO tools, and our own work of using AstroGrid, the United Kingdom national VO, for a research on star formation history of galaxies.

Virtual Flutter Test of Spanwise Curved Wings Using CFD/CSD Coupled Dynamic Method (CFD/CSD 정밀 연계해석기법을 이용한 3차원 곡면날개의 가상 플러터 시험)

  • Kim, Dong-Hyun;Oh, Se-Won;Kim, Hyun-Jung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.457-464
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    • 2005
  • The coupled time-integration method with a staggered algorithm based on computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD) has been developed in order to demonstrate physical vibration phenomena due to dynamic aeroelastic excitations. Virtual flutter tests for the spanwise curved wing model have been effectively conducted using the present advanced computational methods with high speed parallel processing technique. In addition, the present system can simultaneously give a recorded data fie to generate virtual animation for the flutter safety test. The results for virtual flutter test are compared with the experimental data of wind tunnel test. It is shown from the results that the effect of spanwise curvature have a tendency to decrease the flutter dynamic pressure for the same flight condition.

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A Novel Fast Open-loop Phase Locking Scheme Based on Synchronous Reference Frame for Three-phase Non-ideal Power Grids

  • Xiong, Liansong;Zhuo, Fang;Wang, Feng;Liu, Xiaokang;Zhu, Minghua;Yi, Hao
    • Journal of Power Electronics
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    • v.16 no.4
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    • pp.1513-1525
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    • 2016
  • Rapid and accurate phase synchronization is critical for the reliable control of grid-tied inverters. However, the commonly used software phase-locked loop methods do not always satisfy the need for high-speed and accurate phase synchronization under severe grid imbalance conditions. To address this problem, this study develops a novel open-loop phase locking scheme based on a synchronous reference frame. The proposed scheme is characterized by remarkable response speed, high accuracy, and easy implementation. It comprises three functional cascaded blocks: fast orthogonal signal generation block, fast fundamental-frequency positive sequence component construction block, and fast phase calculation block. The developed virtual orthogonal signal generation method in the first block, which is characterized by noise immunity and high accuracy, can effectively avoid approximation errors and noise amplification in a wide range of sampling frequencies. In the second block, which is the foundation for achieving fast phase synchronization within 3 ms, the fundamental-frequency positive sequence components of unsymmetrical grid voltages can be achieved with the developed orthogonal signal construction strategy and the symmetrical component method. The real-time grid phase can be consequently obtained in the third block, which is free from self-tuning closed-loop control and thus improves the dynamic performance of the proposed scheme. The proposed scheme is adaptive to severe unsymmetrical grid voltages with sudden changes in magnitude, phase, and/or frequency. Moreover, this scheme is able to eliminate phase errors induced by harmonics and random noise. The validity and utility of the proposed scheme are verified by the experimental results.

Efficient Hole Searching Algorithm for the Overset Grid System with Relative Body Motion (상대운동이 있는 중첩격자계에 효율적인 Hole Searching Algorithm 개발)

  • Lee, Seon-Hyeong;Chae, Sang-Hyun;Oh, Se-Jong;Yee, Kwan-Jung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.11
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    • pp.995-1004
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    • 2011
  • Object X-ray method commonly used for hole search in overset grids requires huge amount of time due to complicated vector calculations to search the cross-points as well as time-consuming hole search algorithm with respect to background grids. Especially, when the grid system is in motion relative to the background, hole points should be searched at every time step, leading to hung computational burden. To cope with this difficulties, this study presents an efficient hole search algorithm mainly designed to reduce hole searching time. To this end, virtual surface with reduced grid points is suggested and logical operators are employed as a classification algorithm instead of complicated vector calculations. In addition, the searching process is further accelerated by designating hole points in a row rather than discriminating hole points with respect to each background grid points. If there exists a relative motion, the present algorithm requires much less time because only the virtual surface needs to be moved at every time step. The hole searching time has been systematically compared for a few selected geometries.

A Study on the Implementation of outdoor type Virtual Private Network Gateway for Smart Grid (Smart Grid를 위한 필드형 가상사설망(VPN) 게이트웨이의 구현)

  • Park, Jun-Young;Kim, Huy-Kang
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.21 no.4
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    • pp.125-136
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    • 2011
  • The vulnerabilities existed in Korean electricity control systems is unexposed because it is being operated in a closed network with superior security. The threat will become greater once the closed network develops into a smart grid environment with superior intelligence. Security will have a greater impact once each household will be connected to the power plant via the smart meter. This research focuses on stable data transfer in harsh external environment and whole-nation coverage network, and suggested standardized and optimized Virtual Private Network (VPN) Gateway architecture to support Power Line Communication (PLC). The functionality and stability of the prototype has been verified with field tests. For implementation of outdoor type VPN device for smart grid, we adopted PLC low voltage remote-meter-net for data communication. Also, IPSec type tunneling and ARIA algorithm based encryption of data collected by PLC low voltage remote meter is transmitted.

Dynamic Virtual Organization Management System for Grid Based Information Retrieval Service (그리드 기반 정보검색 서비스를 위한 동적 가상 조직 관리 시스템)

  • Kim, Yang-Woo;Lee, Seung-Ha;Kim, Hyuk-Ho
    • The KIPS Transactions:PartD
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    • v.13D no.7 s.110
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    • pp.1009-1016
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    • 2006
  • Under foundational precepts of Grid computing, two important requirements that all Grid application systems should satisfy are to accommodate the dynamic nature of Virtual Organizations (VOs), and to enforce different levels of security among different VOs. For the research described in this paper, we developed two different use-case scenarios addressing the two requirements, and then showed how the requirements can be met by implementing a Grid information retrieval (GIR) system prototype. The dynamic nature of VO applies not only to increasing and decreasing number of users, but also to the dynamically changing requirement of computing power among the different subcomponents that consist in overall system configuration. This implies that a request to increase computing power by a certain subcomponent can be satisfied by other idling subcomponents taking advantage of overall system flexibility. This paper describes how we implemented a Grid IR system using VO and security mechanisms provided by Globus toolkit 3.0, and shows how GIR system scalability and security can be improved for dynamic VOs. In order to manage different VOs, we implemented VO management service (VOMS), and registered it to Globus as an additional service.

Implementation and Performance Evaluation of Migration Agent for Seamless Virtual Environment System in Grid Computing Network (그리드 컴퓨팅 네트워크에서 Seamless 가상 환경 시스템 구축을 위한 마이그레이션 에이전트 구현 및 성능 평가)

  • Won, Dong Hyun;An, Dong-Un
    • KIPS Transactions on Computer and Communication Systems
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    • v.7 no.11
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    • pp.269-274
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    • 2018
  • MMORPG is a role-playing game that tens of thousands of people access it online at the same time. Users connect to the server through the game client and play with their own characters. If the user moves to a management area of another server beyond the area managed by the server, the user information must be transmitted to the server to be moved. In an actual game, the user is required to synchronize the established and the transferred information. In this paper, we propose a migration agent server in the virtual systems. We implement a seamless virtual server using the grid method to experiment with seamless server architecture for virtual systems. We propose a method to minimize the delay and equalize the load when the user moves to another server region in the virtual environment. Migration Agent acts as a cache server to reduce response time, the response time was reduced by 50% in the case of 70,000 people.