• Title/Summary/Keyword: load fluctuation

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New Backstepping-DSOGI hybrid control applied to a Smart-Grid Photovoltaic System

  • Nebili, Salim;Benabdallah, Ibrahim;Adnene, Cherif
    • International Journal of Computer Science & Network Security
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    • v.22 no.4
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    • pp.1-12
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    • 2022
  • In order to overcome the power fluctuation issues in photovoltaic (PV) smart grid-connected systems and the inverter nonlinearity model problem, an adaptive backstepping command-filter and a double second order generalized Integrators (DSOGI) controller are designed in order to tune the AC current and the DC-link voltage from the DC side. Firstly, we propose to present the filter mathematical model throughout the PV system, at that juncture the backstepping control law is applied in order to control it, Moreover the command filter is bounded to the controller aiming to exclude the backstepping controller differential increase. Additionally, The adaptive law uses Lyapunov stability criterion. Its task is to estimate the uncertain parameters in the smart grid-connected inverter. A DSOGI is added to stabilize the grid currents and eliminate undesirable harmonics meanwhile feeding maximum power generated from PV to the point of common coupling (PCC). Then, guaranteeing a dynamic effective response even under very unbalanced loads and/or intermittent climate changes. Finally, the simulation results will be established using MATLAB/SIMULINK proving that the presented approach can control surely the smart grid-connected system.

Performance of Energy Efficient Optical Ethernet Systems with a Dynamic Lane Control Scheme (동적 레인 제어방식을 적용한 에너지 절감형 광 이더넷 시스템의 성능분석)

  • Seo, Insoo;Yang, Choong-Reol;Yoon, Chongho
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.11
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    • pp.24-35
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    • 2012
  • In this paper, we propose a dynamic lane control scheme with a traffic predictor module and a rate controller for reconciling with commercial optical PHY modules in energy efficient optical Ethernet systems. The commercial high speed optical Ethernet system capable of 40/100Gbps employs 4 or 10 multiple optical transceivers over WDM or multiple optical links. Each of the transceivers is always turned on even if the link is idle. To save energy, we propose the dynamic lane control scheme. It allows that several links may be entirely turned off in a low traffic load and frames are handled on the remaining active links. To preserve the byte order even if the number of active links may be changed, we propose a rate controller to be sat on the reconciliation sublayer. The main role of the controller is to insert null byte streams into the xGMII of inactive lanes. For the PHY module, the null input streams corresponding to inactive lanes will be disregarded on inactive PMDs. It is very handy to implement the rate controller module with MAC in FPGA without any modification of commercial PHYs. It is very crucial to determine the number of active links based on the fluctuated traffic load, we provide a simple traffic predictor based on both the current transmission buffer size and the past one with different weighting factors for adapting to the traffic load fluctuation. Using the OMNET++ simulation framework, we provide several performance results in terms of the energy consumption.

Analysis and Prediction for Abutment Behavior of Prestressed Concrete Girder Integral Abutment Bridges (프리스트레스트 콘크리트 거더 일체식 교량의 교대 거동 해석과 예측)

  • Kim, Woo-Seok
    • Journal of the Korea Concrete Institute
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    • v.23 no.5
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    • pp.667-674
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    • 2011
  • This paper discusses the analysis method of prestressed concrete girder integral abutment bridges for a 75-year bridge life and the development of prediction models for abutment displacements under thermal loading due to annual temperature fluctuation and time-dependent loading. The developed nonlinear numerical modeling methodologies considered soil-structure interaction between supporting piles and surrounding soils and between abutment and backfills. Material nonlinearity was also considered to simulate differential rotation in construction joints between abutment and backwall. Based on the numerical modeling methodologies, a parametric study of 243 analysis cases, considering five parameters: (1) thermal expansion coefficient, (2) bridge length, (3) backfill height, (4) backfill stiffness, and (5) pile soil stiffness, was performed to established prediction models for abutment displacements over a bridge life. The parametric study results revealed that thermal expansion coefficient, bridge length, and pile-soil stiffness significantly influenced the abutment displacement. Bridge length parameter significantly influenced the abutment top displacement at the centroid of the superstructure, which is similar to the free expansion analysis results. Developed prediction model can be used for a preliminary design of integral abutment bridges.

The Determining factors and Temporal and Spatial Characteristics of Chemical Oxygen Demand in Jinhae Bay (진해만에 있어서의 COD의 시공간적인 특성 및 결정인자)

  • 김종구;조은일
    • Journal of Environmental Science International
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    • v.8 no.2
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    • pp.189-195
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    • 1999
  • Determining factors and temporal & spatial characteristics of COD(Chemical Oxygen Demand) at the sea surface in Jinhae bay have been examined by using seasonal data, taken at twenty six stations over the whole bay during 1989~1994 by NERDA. The data have been analyzed in terms of long term means, anomalously large values. Jinhae bay is divided into three regions based on the time mean : mouth of Jinhae bay, inner sea of Masan bay, western sea of Jinhae bay called region 1,2 and 3, respectively. The horizontal distribution of the long term mean of COD at each station is similar to those of nitrogen and phosphorus. Characteristics of whole mean variation in the year shows high range of variation in region 2. It was appear to decreases every year in whole trend. Factors determining seasonal variation in whole COD mean are relative to salinity and nutrient, affected by precipitation in summer. Spatial variation shows high range of fluctuation in region 2 compare to other region. Factors determining of spatial variation of COD was appear to nutrient, affected by pollutant load of land area and bottom sediment. The long term mean of COD at each station is closely related with thats of nutrients. The correlation coefficient between COD and nitrogen, phosphate phosphorus was found to be high as 0.75, 0.78, respectively. Anomalously large COD was observed 14 times at 6 stations. These stations are located in inner sea of Masan bay(Region 2) and Songjeong bay(Region 1). The seasonal frequency of the observed anomalous COD is large in April, and other seasons are much the same.

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A Study on Feed Rate Characteristics of Motor-driven Cylinder Lubricator with Electronic Control Quill in a Large Two-stroke Diesel Engine (대형 2행정 디젤기관에 있어서 전자제어 퀼 부착 모터구동 실린더 주유기의 송출유량 특성에 관한 연구)

  • Bae, Myung-Whan;Jung, Hwa;Jung, Yeun-Hak;Kim, In-Deok;Kang, Chang-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.6
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    • pp.1-8
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    • 2007
  • Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke marine diesel engine is of great economic importance. In Korea, authors first developed a motor-driven cylinder lubricator for a Wartsila Switzerland large two-stroke diesel engine. The characteristic of the developed product is that can control automatically the oil feed rate with a load fluctuation by the motor drive and the offset cam. For manufacturing the reliable and useful products, however, it is necessary to investigate further characteristics and to improve performances as a cylinder lubricator. In this study, the effects of pump motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill injection system and distributer in the developed cylinder lubricator. It is found that the oil feed rates of electronic control and mechanical type quills with the in-cylinder back pressure are differently characterized by the role of accumulator, the viscous resistance of contact area, etc. It can be also shown that the maximum discharge pressure of the electronic control quill is lower than the mechanical type one but the maximum discharge pressure difference of two types decreased as plunger stroke is small, and the maximum delivery pressures of two types increased as plunger stroke, motor speed and back pressure are elevated but the maximum delivery pressure of mechanical type is higher than the one of electronic control type.

Effects of Downstream Cylinder by Changing Upstream Object's Diameter (상류에 있는 물체의 직경변화에 따라 후류 물체가 받는 영향)

  • Kim, Sang Il
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.10
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    • pp.859-864
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    • 2014
  • This experimental study investigates the effects of a downstream cylinder in the wake change on upstream object's diameter. A V-shaped object is placed in the upstream of the test section and a circular cylinder containing a load-cell is placed in the downstream. The velocity distribution of the wake generated from the upstream object with a change in its diameter is investigated. Further, the fluctuation in the lift coefficient and Karman-vortex emission frequency with a change in the position of the downstream cylinder is examined. The study results reveal the following. i) The flow velocity in the wake is smaller than that in the main stream. ii) The lock-in phenomenon occurs when the diameter of the upstream object is larger than that of the downstream cylinder. iii) To generate maximum fluctuating lift force of the downstream cylinder in the wake, the position of the downstream cylinder must be moved with changing diameter of the upstream object together.

A Study on Effect of Quill Accumulator upon Performance of Motor-driven Cylinder Lubricator in a Large Two-stroke Diesel Engine (대형 2행정 디젤기관용 모터구동 실린더 주유기의 성능에 미치는 퀼 어큐뮬레이터의 영향에 관한 연구)

  • Bae, Myung-Whan;Ok, Hyun-Jin;Jung, Hwa
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.115-125
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    • 2007
  • Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke marine diesel engine is of great economic importance. In Korea, a motor-driven cylinder lubricator for a large two-stroke marine diesel engine manufactured by $W{\ddot{a}}rtsil{\ddot{a}}$ Switzerland Co., Ltd. was first developed by authors through the joint research of industry-university in 2002. The characteristic of the developed product is that can control automatically the oil feed rate to a load fluctuation by the motor drive and the offset cam. The performance of the product is not also inferior to the conventional one. For manufacturing the reliable and useful products, however, it is necessary to investigate further characteristics and improve the performance of a cylinder lubricator. In this study, the effect of quill with and without accumulator on maximum discharge pressure, delivery delay duration and oil feed rate relative to motor revolution speed using plunger stroke as a parameter is experimentally investigated by using the developed cylinder lubricator. It is found that the maximum discharge pressure with accumulator is higher than that of no accumulator as plunger stroke and motor revolution speed are elevated, and the delivery delay duration with accumulator is shorter than that of no accumulator as plunger stroke and motor revolution speed are increased. Also, oil feed rate with accumulator is less than that of no accumulator except for a plunger stroke of 2 mm as plunger stroke and motor revolution speed are raised.

Hormonic Evaluation of An Imported IAT(Intra Airport Transit) System in Incheon International Airport (인천 국제공항청사 경전철 도입에 따른 고조파 영향 분석)

  • Kim, Jin-O;Song, Hak-Seon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.1
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    • pp.41-47
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    • 2006
  • This paper presents harmonic evaluation of an IAT(Intra Airport Transit) system in Incheon International Airport. It will be used for electric vehicles with 80[kW] per car produced by Mitsubishi Heavy Industries Ltd, and which is constructed with SIV(Static Inverter), VVVF controller and two induction motor. The vehicles operated in the IAT system can be treated as rapidly changing DC loat and at a feeding substation, 3-phase electric power is transferred to DC 750[V] by rectifier. Since vehicles are changing continuously, the voltages for the load fluctuate in the IAT system, and moreover, the voltage fluctuation generates high-order harmonics. It results the difficulty in maintaining power quality in KEPCO systems' side. The power quality of the IAT system in Incheon International Airport is evaluated using PSCAD/EMTDC simulator in the paper. The THD(Total Harmonic Distortion) of voltages and TDD(Total Demand Distortion) of currents, indices are calculated for the IAT system using the results of PSCAD/EMTDC dynamic simulation.

A Study of Interference-Free Home PLC based on the Binary ZCD Code (연속직교 상관특성을 갖는 아진 코드 기반의 구내용 PLC에 관한 연구)

  • Cha, Jae-Sang;Kim, Seong-Kweon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.2
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    • pp.38-44
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    • 2006
  • In this paper, a new interference-free Home CDMA-PLC(Code Division Multiple Access-Power Line Communication) system based on the binary ZCD(Zero Correlation Duration) spreading code is proposed as a key solution to overcome the previous problems. Binary ZCD spreading code sets with enlarged family sizes are generated by carrying out a chip-shift operation of the preferred pairs. The properties or the proposed ZCD-PLC systems are effective for MPI(Multi-Path Interference) and MAI (Multiple Access Interference) cancellation in the CDMA-PLC systems. By BER performance simulation, we certified the availability of proposed ZCD-CDMA-PLC system.

A Study on the Behaviour of an Earth and Rockfill Dam Due to Reservoir Water (저수변화에 따른 사력댐의 거동 연구)

  • Shin, Jong-Ho
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.61-70
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    • 2003
  • The behaviour of an earth and rock-fill dam is complicated due to reservoir water and various materials in zoned dams. Different materials with a wide range of permeability and seasonal variation of reservoir water result in the time dependent post-constructional behaviour. In aged dams it is often required to control water level to keep the dams safe. In this case information on the post-constructional dam behaviour is important. However, present geotechnical knowledge does not fully support the occasion. In this study the post-constructional behaviour of a dam is investigated using coupled finite element models for series of idealized water reservoir cases: impoundment, draw down, seasonal fluctuation with different rising and falling speeds. Numerical results were analysed in respect of geotechnical parameters such as load transfer, hydraulic fracturing potential and stress paths. It is shown that the control of water level is an important factor while operating dams.