• Title/Summary/Keyword: Three Phase Load Flow

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Effect of Chamfering Top Corners on Liquid Sloshing in the Three-dimensional Rectangular Tank (챔퍼가 3차원 사각 탱크 내부의 액체 슬로싱에 미치는 영향)

  • Jung, Jae-Hwan;Lee, Chang-Yeol;Yoon, Hyun-Sik
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.4
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    • pp.508-516
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    • 2010
  • This study aims at investigating the effect of the chamfer on the liquid sloshing in the three-dimensional (3D) rectangular tank. In order to simulate the 3D incompressible viscous two-phase flow in the 3D tank with partially filled liquid, the present study has adopted the volume of fluid (VOF) method based on the finitevolume method which has been well verified by comparing with the results of the relevant previous researches. The effects of the chamfering top corners of the tank on the liquid sloshing characteristics have been investigated. The angle of the chamfering top corners (${\theta}$) has been changed in the range of $0^{\circ}{\leq}{\theta}{\leq}60^{\circ}$(${\Delta}{\theta}=15^{\circ}$) to observe the free surface behavior, and the effect on wall impact load. Generally, as the angle of the chamfering top corners increases, the impact pressure on the upper knuckle point decreases. However it seemed that a critical angle of the chamfering top corners exists to reveal the lowest impact pressure on the wall.

The Study on the Voltage Improvement in Distribution Line(I) (배전선로(配電線路)의 전압개선(電壓改善) 대책(對策)에 관한 연구(硏究)(I))

  • Kim, Ho-Yong;Rho, Dae-Sook;Son, Soo-Kook;Kim, Sang-Jun;Son, Il-Keun
    • Proceedings of the KIEE Conference
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    • 1988.07a
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    • pp.888-891
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    • 1988
  • Recently, with the expansion of electronic equipment and computer facilities, good quality of services is required. This paper describes how to improve distribution system voltage by the Tap position seletion of P. Tr, by the decision of the optimal sending voltage in substation and we also developed three phase load flow program in distribution system. Besides we have developed the digital recording voltmeter that will be utilized with personal computer system. This meter will be useful, economical and powerful.

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Optimal Capacitor Placement and Control using Genetic Algorithms in Unbalanced Distribution Systems. (불평형 배전계통에 있어서 유전알고리즘을 이용한 커패시터의 적정 배치 및 제어)

  • Kim, Kyu-Ho;You, Seok-Ku
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.7
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    • pp.839-846
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    • 1999
  • This paper presents an efficient algorithm for determining the location, size and number of capacitors in unbalanced radial distribution system. The objective function formulated consists of two terms: cost for energy loss and cost related to capacitor purchase and capacitor installation. The cost function associated with capacitor placement is considered as step function due to banks of standard discrete capacities. Genetic algorithms(GA) are used to obtain the population is derived. The strings in each population consist of the bus number index and size of capacitors to be installed. In order to determine the number of capacitor placement, the length mutation operator is used. Its efficiency is proved through the application in unbalanced radial distribution systems made of 10 buses with 9 distribution lines and 25 buses with 24 distribution lines.

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Enhancement of network stability using flywheel Energy storage unit and circulating type cycloconverter (플라이휠과 순환전류형 싸이크로컨버터를 이용한 계통안정도 향상)

  • Ryu, Ho-Seon;Kim, Byung-Kweon;Whang, In-Ho;Lee, Heung-Ho;Seong, Se-Jin
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.202-204
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    • 1993
  • Appropriate control of real and reactive power flowing in and out from system can lead to considerable benefits : network stabilization, load leveling, voltage regulation etc. This paper presents how to control real and reactive power flow between an flywheel energy storage system and a power three phase network. The system compensating real and reactive power consists of control system and cycloconverter operating in the four quadrant modes.

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Aerodynamic Shape Design of a Partial Admission Turbine Using CFD (CFD를 이용한 부분흡입형 터빈 공력형상 설계)

  • Lee, Eun-Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.11 s.254
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    • pp.1131-1138
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    • 2006
  • Aerodynamic shape design of a partial admission turbine using CFD has been performed. Two step approaches are adopted in this study. Firstly, two-dimensional blade shape is optimized using CFD and genetic algorithm. Initially, the turbine cascade shape is represented by four design parameters. By controlling the design parameters as variables, the non-gradient search is analyzed for obtaining the maximum efficiency. The final two-dimensional blade proved to have a more blade power than the initial blade. Secondly, the three-dimensional CFD analysis including the nozzle, rotor and stator has been conducted. To avoid a heavy computational load due to an unsteady calculation, the frozen rotor method is implemented in steady calculation. The frozen rotor method can detect a variation of the flow-field dependent upon the blade's circumferential position relative to the nozzle. It gives a better idea of wake loss mechanism starting from the lip of the nozzle than the mixing plane concept. Finally, the combination of two and three dimensional design method of the partial admission turbine in this study has proven to be a robust tool in development phase.

A Study on Future System Construction Using WSCR Strengthness Index based on Python (Python 기반 WSCR 강건 지수를 이용한 미래계통 구축에 관한 연구)

  • Park, Seong-Jun;Hur, Jin;Kim, Hyun-Jin;Cho, Yoon-Sung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.8
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    • pp.994-1001
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    • 2018
  • In this paper, to studied about future power system construction using PSS / E-Python API. Python-based future system automatical construction methods and modeling of renewable sources. it confirmed the stability of the powert system for each renewable area by calculating the weighted short circuit ratio (WSCR) index. it calculated the short circuit ratio (SCR) and selected the transmission line linkage scenario to improve the stability of vulnerable areas. it confirmed the WSCR index improvement through the selected transmission line linkage of scenario, and analyzed the stability of the renewable power system applying the scenario. It describes Facts and Shunt devices adjustment for the load flow convergence. It describes the stable methed of the bus voltage through the transformer Ratio Tap adjustment. By performing PSS/E ASCC using the Python it was performed three-phase short circuit fault capacity analysis, it is confirmed whether excess of the fault current circuit breaker capacity. In order to contingency accident analysis, it have described the generation of one or two line list of each areas using the Python. The list is used to contingency analysis and describe the soluted of the transmission line overload through comparison before and after adding the scenario line.

A Study on the Water Quality Improvement of Major Tributaries in Seoul, Applying Watershed Evaluation Techniques (총량관리 단위유역 평가기법을 활용한 서울특별시 주요 유입 지천의 수질개선효과에 관한 연구)

  • Shim, Kyuhyun;Kim, Gyeonghoon;Im, Taehyo;Kim, Youngseok;Kim, Seongmin
    • Journal of Korean Society on Water Environment
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    • v.37 no.1
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    • pp.32-46
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    • 2021
  • South Korea has been divided into quantities and water quality, and due to a revision of the Government Organization law in June 2018, the controversial water management system was integrated into the Ministry of Environment. The total Maximum Daily Loads System has been called the flower of water quality control, and since 2004, all three major river systems which have been introduced into the Han River system, despite its various difficult environments, and subsequently leading to all of the four major rivers undergoing obligatory implementation since 2013. Currently, the target TMDL (Han River Phase 1 and Other Water Systems Phase 3) for the 2020 stage has been implemented. The domestic TMDL established a basic plan for calculating the load which complies with the unit watershed's target water quality, as well as an implementation plan for annual load management, both which have been institutionalized in order to evaluate load compliance on a repeated annual basis. Local governments ask external organizations to conduct investigations every year in order to assess the transition, which thereby requires tens of millions of won every year. Therefore, an assessment and management model that can be easily operated at the TMDL personnel level is required. In this study, when the Han river Water System TMDL was implemented in earnest, we confirmed the the water quality improvement effect when TMDL was introduced to major inflow tributaries (TancheonA, JungnangA, AnyangA) under the Seoul City's jurisdiction through the use of the total amount control unit basin evaluation technique. By presenting customized management measures, we propose the guidelines that are necessary for determining more effective water environmental policies.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.