• Title/Summary/Keyword: 분산전원

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A Study on Fault Characteristics of DFIG in Distribution Systems Based on the PSCAD/EMTDC (PSCAD/EMTDC를 이용한 풍력발전의 배전계통 사고특성에 관한 연구)

  • Son, Joon-Ho;Kim, Byung-Ki;Jeon, Jin-Taek;Rho, Dae-Seok
    • Journal of the Korea Convergence Society
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    • v.2 no.2
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    • pp.47-56
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    • 2011
  • Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

Geochemical Dispersion and Contamination Characteristics of Heavy Metals in Soils and Leaves of Ginkgo biloba in Seoul Area (서울지역 가로수 토양과 은행나무 잎 중의 중금속 원소들의 지구화학적 분산과 오염특성)

  • Choo Mi-Kyung;Kim Kyu-Han;Lee Jin-Soo;Chon Hyo-Taek
    • Economic and Environmental Geology
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    • v.38 no.3 s.172
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    • pp.221-236
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    • 2005
  • In order to investigate the contamination levels and dispersion patterns of heavy metals such as Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn by urbanization, soils beneath roadside-trees and leaves of Ginkgo biloba were collected from Seoul area during October to November in 2001. All tree leaves were grouped into washed and unwashed ones. The pH of most soil ranges from 6 to 9 indicating a weak acidic and alkaline. The element couples of Cd-Co, Cr-Ni and Zn-Cu-Pb have good correlation in soils, and contamination sources of Cd-Co, Cr-Ni and Zn-Cu-Pb could be similar. High correlation coefficients among Pb, Cu and Zn in G. biloba indicates that these elements show the similar behavior during the metabolism processes. From the results of pollution index calculation for soils, industrialized and heavy traffic area were severly polluted by heavy metals such as Cd, Cu, Pb and Zn. By the discriminant analysis, industrialized and heavy traffic areas are enriched in the order of Ni> Cr> Pb. Cadmium is useful to discriminate between industrialized and heavy traffic areas, Co and Pb are highly enhanced in heavy traffic area.

A Study on System Retrofit of Complex Energy System (복합에너지시스템의 성능개선에 관한 연구)

  • Choi, Jung-Hun;Moon, Chae-Joo;Chang, Young-Hak
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.1
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    • pp.61-68
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    • 2021
  • The application of renewable energies such as wind and solar has become an inevitable choice for many countries in order to achieve the reduction of greenhouse gases and healthy economic development. However, due to the intermittent characteristics of renewable energy, the issue with integrating a larger proportion of renewable energy into the grid becomes more prominent. A complex energy system, usually consists of two or more renewable energy sources used together to provide increased system efficiency as well as greater balance in energy supply. Compared with the power system, control and optimization of the complex energy system become more difficult in terms of modeling, operation, and planning. The main purpose of the complex energy system retrofit for samado island with microgrid system is to coordinate the operation with various distributed energy resources, energy storage systems, and power grids to ensure its reliability, while reducing the operating costs and achieving the optimal economic benefits. This paper suggests the improved complex energy system of samado island with optimal microgrid system. The results of test operation show about 12% lower SOC variation band of ESS, elimination of operation limit in PV and reduction of operation time in diesel generator.

Current Calculation Simulation Model for Smartgrid-based Energy Distribution System Operation (스마트 그리드 기반 에너지 시스템 운영을 위한 배전계통 조류계산 시뮬레이션 모델 개발)

  • Bae, HeeSun;Shin, Seungjae;Moon, Il-Chul;Bae, Jang Won
    • Journal of the Korea Society for Simulation
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    • v.30 no.1
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    • pp.113-126
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    • 2021
  • The future energy consumption pattern will show a very different pattern from the present due to the increase of distributed power sources such as renewable energy and the birth of the concept of prosumers, etc. Accordingly, it can be predicted that the direction of establishment of an appropriate production and supply plan considering the stability and consumption efficiency of the entire power grid will also be different from now. This paper proposes a simulation model that can test a new operational strategy when faced with a number of possible future environments. Through the proposed model, it is possible to simulate and analyze power consumed and supplied in a future Smart Grid environment, in which a large amount of new concepts including energy storage service (ESS) and distributed energy resources (DER) will be added. In particular, it is possible to model complex systems structurally by using DEVS formalism among the ABM (Agent-Based Model) methodologies that can model decision-making for each agent existing in the grid, and several factors can be easily added to the grid. The simulation model was verified using given dataset in the current situation, and scenario analysis was performed by simply adding an ESS, one of the main elements of the smart grid, to the model.

Evaluation of Technical Production Efficiency and Business Structure of Domestic Combined Heat and Power (CHP) Operators: Panel Stochastic Frontier Model Analysis for 16 Collective Energy Operators (국내 열병합발전사업의 기술적 생산효율성 추정 및 사업구조 평가: 16개 집단에너지사업자에 대한 패널 확률프론티어모형(SFA) 분석)

  • Lim, Hyungwoo;Kim, Jaehyeok;Shin, Donghyun
    • Environmental and Resource Economics Review
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    • v.30 no.4
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    • pp.557-579
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    • 2021
  • Collective energy is an intermediate stage in energy conversion and has a great influence on the power structure as a distributed power source. However, the problem of the collective energy business has recently emerged due to the worsening profitability of some collective energy operators. This study measured the technical efficiency of major operators through the estimation of the production efficiency of Korean collective energy operators, and based on this, we looked at ways to improve the profit structure of operators. After collecting detailed data from 16 collective energy operators between 2016 and 2019, the production efficiency of operators was estimated using the panel stochastic frontier model. As a result of the estimation, combined steam power operators showed the highest production efficiency and reverse CHP operators showed the lowest efficiency. Furthermore, as a result of examining the factors influencing profitability, it was confirmed that production efficiency has a positive effect on overall profitability. However, businesses with a high proportion of heat production, such as small district electricity operators, profitability was lower. This phenomenon is due to the structural limitations of the current heat sales market. Hence, the adjustment of the heat sales unit price is necessary to improve profitability of collective energy operators.

Study on a Limit MPPT Controller for the Modelling of a Wind Power Generator (풍력발전기 모델링 및 리미트 MPPT제어기에 관한 연구)

  • Kang, Ju-Sung;Koh, Kang-Hoon;Choi, Kwang-Ju;Park, Jae-Yoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.5
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    • pp.53-59
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    • 2007
  • Now, the study is activity that the energy market depending on a fossil fuel tend to change different way. In middle of the study compositive use of renewable energy(fuel cell and wind power, solar cell, etc.) is dispersion power system which concern is increasing. But in the case of generation of electric wind power system is changeable to be turbulence and wind and win speed are changeable in several seconds, so making the best of wind energy the MPPT that role in this case is important. In this paper suggest a MPPT which is making a use of information of wind speed and turning speed, windmill, electric power but it is simpler than former way. We could verify that a proposed controller working at the highest point of electric power when wind speed is regular speed and changable speed through the simulation.

Analysis of Customer Power Quality Characteristics Using PV Test Devices (태양광전원 계통연계시험장치에 의한 수용가 전력품질특성에 관한 연구)

  • Kim, Byungmok;Kim, Byungki;Park, Jeabum;Rho, Daeseok
    • Journal of the Korea Convergence Society
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    • v.2 no.4
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    • pp.21-27
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    • 2011
  • Recently, new distributed power sources such as photovoltaic, wind power, fuel cell systems etc. are energetically interconnected and operated in the distribution feeders, as one of the national projects for alternative energy. When new power sources are considered to be interconnected to distribution systems, bi-directional power flow and interconnection conditions of new power sources may cause several power quality problems like voltage sag, voltage swell, harmonics, since new power sources can change typical characteristics of distribution systems. Under these situations, this paper deals with the analysis the power quality problems at primary and secondary feeders in distribution systems, when new power sources like photovoltaic (PV) systems are interconnected, by using the test devices for PV systems based on the LabVIEW S/W. This paper presents the test device which is consisted with model distribution system and model PV systems. By performing the simulation for power quality operation characteristic based on the test facilities, this paper presents the optimal countermeasures for power quality.

Radiation Characteristics of Noise Generated by Steady Loading on Rotating Blade (회전익 표면의 정상하중에 의한 소음의 방사특성)

  • Jeon, Wonju;Lee, Duck-Joo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.4
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    • pp.307-314
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    • 2008
  • Loading noise generated by steady aerodynamic force exerted on the rotating body surface is theoretically analyzed and its radiation characteristics is examined as a fundamental research of helicopter rotor noise. For simplicity, the force exerted on each blade is not distributed but concentrated at one point and the noise is evaluated by using Lowson' exact formula with a discussion of the physical meaning of each term in the formula. For a single point force rotating with various angular frequencies, we investigated the radiation characteristics and theoretically explained the physical behavior at near and far-field. By investigating the amplitude of acoustic pressure with various distances, we observed the different decreasing ratio at near- and far-field with the discussion of the effect of acceleration of angular frequency. Finally, the phenomenon that the noise level is reduced everywhere as the number of blade increases is explained with the suggestion of a noise reduction idea, the limitations of this study, and the future research topics.

Optimal Sizing Method of Distributed Energy Resources for a Stand-alone Microgrid by using Reliability-based Genetic Algorithm (신뢰도 기반의 유전자알고리즘을 활용한 독립형 마이크로그리드 내 분산형전원 최적용량 산정 방법)

  • Baek, Ja-Hyun;Han, Soo-Kyung;Kim, Dae-Sik;Han, Dong-Hwa;Lee, Hansang;Cho, Soo-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.5
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    • pp.757-764
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    • 2017
  • As the reduction of greenhouse gases(GHGs) emission has become a global issue, the microgrid markets are growing rapidly. With the sudden changes in the market, Korean government suggested a new business model called 'Self-Sufficient Energy Islands'. Its main concern is a stand-alone microgrid composed of Distributed Energy Resources(DERs) such as Renewable Energy Sources(RESs), Energy Storage System(ESS) and Fuel Cell, in order to minimize the emission of GHGs. According to these trend, this paper is written to propose an optimal sizing method of DERs in a stand-alone microgrid by using Genetic Algorithm(GA), one of the representative stochastic methods. It is to minimize the net present cost with the variables, size of RESs and ESS. In the process for optimization, the sunless days are considered as additional constraints. Through the case study analysis, the size of DERs installed in a microgrid system has been computed using the proposed method in MATLAB. And the result of MATLAB is compared with that of HOMER(Hybrid Optimization of Multiple Energy Resources), a well-known energy modeling software.

Query Processing using Partial Indexs based on Hierarchy in Sensor Networks (센서 네트워크에서 계층기반 부분 인덱스를 이용한 질의처리)

  • Kim, Sung-Suk;Yang, Sun-Ok
    • Journal of KIISE:Databases
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    • v.35 no.3
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    • pp.208-217
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    • 2008
  • Sensors have a function to gather environment-related information operating by small-size battery in sensor networks. The issue related with energy is still an important in spite of the recent advancements in micro-electro-mechanical-system(MEMS) related techology. Generally it is assumed that replacement or rechargement of battery power in sensor is not feasible and a message send operation may spend at least 1000 times battery than a local operation. Thus, there have been several kinds of research efforts to lessen the number of unnecessary messages by maintaining the information of the other neighboring(or all) sensors. In this paper, we propose an index structure based on parent-children relationship to the purpose. Namely, parent node gathers the set of location information and MBA per child. It's named PH and may allow to process the range query with higher accurate and small size information. Through extensive experiments, we show that our index structure has better energy consumption.