• Title/Summary/Keyword: flow control

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UPFC Device: Optimal Location and Parameter Setting to Reduce Losses in Electric-Power Systems Using a Genetic-algorithm Method

  • Mezaache, Mohamed;Chikhi, Khaled;Fetha, Cherif
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.1
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    • pp.1-6
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    • 2016
  • Ensuring the secure operation of power systems has become an important and critical matter during the present time, along with the development of large, complex and load-increasing systems. Security constraints such as the thermal limits of transmission lines and bus-voltage limits must be satisfied under all of a system’s operational conditions. An alternative solution to improve the security of a power system is the employment of Flexible Alternating-Current Transmission Systems (FACTS). FACTS devices can reduce the flows of heavily loaded lines, maintain the bus voltages at desired levels, and improve the stability of a power network. The Unified Power Flow Controller (UPFC) is a versatile FACTS device that can independently or simultaneously control the active power, the reactive power and the bus voltage; however, to achieve such functionality, it is very important to determine the optimal location of the UPFC device, with the appropriate parameter setting, in the power system. In this paper, a genetic algorithm (GA) method is applied to determine the optimal location of the UPFC device in a network for the enhancement of the power-system loadability and the minimization of the active power loss in the transmission line. To verify our approach, simulations were performed on the IEEE 14 Bus, 30 Bus, and 57 Bus test systems. The proposed work was implemented in the MATLAB platform.

Analysis of Coal Combustion and Particle Temperature Profiles in a Rotary Kiln for Production of Light-weight Aggregate (경량골재 로타리킬른의 운전최적화를 위한 석탄연소 및 원료입자 승온특성 해석)

  • Park, Jong-Keun;Ryu, Changkook;Kim, Young-Ju
    • Journal of the Korean Society of Combustion
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    • v.19 no.3
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    • pp.18-25
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    • 2014
  • Bottom ash from a coal-fired power plant is usually landfilled to a nearby site, which causes a growing environmental concern and increased operating costs. One way of recycling the bottom ash is to produce light-weight aggregate (LWA) using a rotary kiln. This study investigated the temperature profiles of raw LWA particles in a rotary kiln to identify the range of operating conditions appropriate for ideal bloating. For this purpose, a new simulation method was developed to integrate a 1-dimensional model for the bed of LWA particles and the computational fluid dynamics (CFD) for the fuel combustion and gas flow. The temperature of LWA particles was found very sensitive to the changes in the air preheating temperature and excess air ratio. Therefore, an accurate control of the operation parameters was essential to achieve the bloating of LWA particles without excessive sintering or melting.

Geotectonic Movements and Metal Ore Deposits in South Korea (남한(南韓)의 지구조운동(地構造運動)과 금속광상(金屬鑛床))

  • Shin, Byung Woo
    • Economic and Environmental Geology
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    • v.7 no.1
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    • pp.1-21
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    • 1974
  • From the point of view of geological history, the land of South Korea is regarded as the subject of processes of the changes in formations of several geological blocks such as Kyonggi massif, Yeongnam massif, Taebaegsan basin, Kyungsang basin and so on. Through the long period of geological chronology, the present topography and geotectonics have been formed by the complicate interactions of epirogenetic movements, magmatism, orogenesis, differential vertical movements, metamorphism and sedimentation. The reason of the crust movements mentioned above, is suppossed that the Pacific and West Pacific plate have subducted directly or indirectly into the East Asia plate. This fact can be endorsed by the results of the studies on the heat flow, gravity anomaly, absolute age dating, tectonic lineation, lithofacies and the temperature of hot spring in South Korea. The formations of metal ore deposits as well as other geological processes can be determined by the mechanical control of the plates and be divided into several systematic patterns. The investigation of about 110 metal mines in South Korea shows the following results. (1) Plate boundary volcanic type is about 28% (2) Plate boundary plutonic type is about 44% (3) Intraplate sedimentary type is about 26% (4) Intraplate magmatic type is about 2%.

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Experimental Research on the Power Saving Effect Evaluation of a Variable Displacement Vane Pump for an Automatic Transmission (자동변속기용 가변 용량 베인 펌프의 파워 절감 효과 평가에 대한 실험적 연구)

  • Kim, Chulsoo;Bae, Chulyong;Kim, Chanjung;Kim, Kyusik;Son, Taekwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.7
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    • pp.1-7
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    • 2014
  • A variable displacement vane pump is possible to improve the fuel economy by varying the pump capacity with a vane mechanism according to the engine operating speed range and reducing its driving torque. In general the experimental evaluation of the vane pump for the transmission has been performed mainly not with the vehicle or dynamometer test rig but with component test rig due to the implementation and safety problems. In this paper, in order to evaluate the performance of the developed vane pump as well as the compatibility with other rotary and hydraulic components of the target transmission, the transmission dynamometer based test rig is implemented where the developed pump is built into it and then the variable pump capacity and effect of power reduction are investigated experimentally.

Thermal Fluid Flow and Deformation Analysis of Medium Commercial Vehicle Ventilated Brake Disc in Braking (중형 상용차 통풍형 브레이크 디스크의 제동 시 열 유동 및 변형 해석)

  • Kang, Chaeuk;Choi, Gyoojae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.7
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    • pp.63-69
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    • 2014
  • Domestic automobile companies have adopted drum type brake system for commercial vehicles. However recently those companies have been applying disc-brake system to solve vehicle control-instability and inefficient heat discharge performance of conventional drum brake system for a medium commercial vehicle. Because the kinetic energy of a running commercial vehicle is relatively high, the brake system should discharge lots of heat energy while braking. A ventilated type brake disc has been used to increase heat discharge performance of a brake system. The vent structure of a disc highly affects cooling efficiency. This paper compares thermal characteristics of three types of vent structure in JASO C421 braking condition. It is found that the slant bend type disc has the lowest temperature and thermal stress distributions in the braking condition.

Development of High-speed Elevator Drive System using Permanent-magnet Synchronous Motor (영구 자석형 동기 전동기를 이용한 고속 엘리베이터 구동 시스템 개발)

  • Ryu Hyung-Min;Kim Sung-Jun;Sul Seung-Ki;Kwon Tae-Seok;Kim Ki-Su;Shim Young-Seok;Seok Ki-Riong
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.385-388
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    • 2001
  • In this paper, the gearless traction machine drive system using a permanent-maget motor for high-speed elevators is addressed. This application of permanent-magnet motor to the elevator traction machine enables several improvements including higher efficiency, better ride comfort, smaller size and weight, and so on. PWM boost converter is also adopted so that DC-link voltage regulation, hi-directional power flow, and controllable power factor with reduced input current harmonics are possible. To increase reliability and performance, the control board, which can include the car and group controller as well as PWM converter and inverter controller, is designed based on TMS320VC33 DSP The simulator system for high-speed elevators has been developed so that the drive system of high-speed elevator can be tested without my limitation on ride distance and the load condition. Some experimental results are given to verify the effectiveness of the developed system.

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Assessment of Flood Impact on Downstream of Reservoir Group at Hwangryong River Watershed (황룡강 유역 저수지군 하류하천 영향평가)

  • Hwang, Soon-Ho;Kang, Moon-Seong;Kim, Ji-Hye;Song, Jung-Hun;Jun, Sang-Min;Lee, Sang-Hyun;Choi, Jin-Yong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.3
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    • pp.103-111
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    • 2012
  • Works for dam heightening plan have dual purposes: flood disaster prevention by securing additional storage volume and river ecosystem conservation by supplying stream maintenance flow. Now, the dam heightening project is in progress and there are 93 dam heightened reservoir. After the dam heightening project, 2.2 hundred million ton of flood control volume in reservoirs will be secured. Thus it is necessary to evaluate the effects of the dam heightening project on watershed hydrology and stream hydraulics, and resulting flood damages. This study was aimed to assess the impact of outflow from the dam heightened reservoir group on the Whangryong river design flood. The HEC-HMS (Hydrologic Engineering Center-Hydrologic Modeling System) model was used for estimating flood discharge, while HEC-5 (Hydrologic Engineering Center-5) was used for reservoir routing. This study analysed flood reduction effect on 100yr and 200yr return periods about the before and after heightening of agricultural dams. Based on the results of this study, the reduction of flood peak discharge at downstream of the reservoir group was estimated to be about 41% and 53% for 100yr and 200yr frequencies, respectively.

Analysis of Flow and Congestion control in USN (USN의 전송 계층 프로토콜에서 에러 및 흐름제어의 성능 평가)

  • Cha, Hyun-Soo;Kang, Chul-Kun;Yoo, Seung-Wha;Kim, Ki-Hyung
    • 한국정보통신설비학회:학술대회논문집
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    • 2008.08a
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    • pp.45-50
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    • 2008
  • Many applications of sensor network require connection to the Internet. The transmission protocol of traditional sensor network was designed within the sensor network itself. However, based on 6LoWPAN which can be accessed using IPv6, direct connection is possible between the sensor network and the TCP/IP network outside. Transmission of data in applications of sensor network falls into two main categories. One is a small packet that is periodically produced such as packet related to temperature and humidity. The other is a relatively large packet that brings about network overheads such as images. We investigated the conformance test and pros and cons of application data over the transmission protocol of Zigbee and 6LoWPAN. As a result, both Zigbee and 6LoWPAN have shown low rate of loss for periodic data and have in creased reliability of data transfer. When transmitting streaming image data, both ACK, non ACK mode of Zigbee and UDP of 6LoWPAN minimized transmission time but suffered the consequences of high packet loss. Even though TCP of 6LoWPAN required a long transmission time, we were able to confirm that no loss has occurred.

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Handoff Processing for Mobile Agent in Distributed Environment (분산 환경에서의 이동 에이전트 핸드오프 처리)

  • Park, Ki-Hyun
    • The KIPS Transactions:PartC
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    • v.8C no.6
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    • pp.815-820
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    • 2001
  • This paper presents a distributed mobile architecture aimed to support the mobility of mobile station. The proposed architecture considers three significant objects;mobile station (MS), mobile agent (MA) which logically represents mobile station in the wireline network, and trace agent (TA) to represent application server (AS) providing application service to mobile station. The mobile agent is made closely coupled with the mobile station while the trace agent is made closely coupled with the application server. During the handoff process, a flow control mechanism is considered to correct packet loss and out-of-sequence packets problem. The result of analytic additional time delay due to handoff processing is presented and simulation was performed to check the additional time delay as well as the correctness of handoff algorithm.

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Development of the controller for peeling off the enamel and forming of deflection yoke coil (편향요크코일의 에나멜 탈피 및 통전성형을 위한 탈피통전기의 개발)

  • Jeong, Soo-Hoa;Yun, Jong-Soon;Kwon, Woo-Hyun
    • Proceedings of the KIEE Conference
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    • 1995.07a
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    • pp.202-205
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    • 1995
  • Developed controller is the part of deflection yoke winding machine which controls the power to form the deflection yoke coil into desired shape after winding. So as to form the deflection yoke coil, it is needed to melt the bonding material which is spreaded on the coil. The heat melt the bonding material which is produced by flowing the current through the winded coil. Therefore, at first it is needed to peel off the enamel from the winded coil so as to flow the current, and then supply the power to produce the heat which form the winded coil into desired shape. Naturally developed controller is composed of the peeling part and the conduction and forming part. All of them consist of the inverter structure and control the output current. The peeling is achieved by low voltage and high AC current, the conduction and forming is by DC current. Developed controller also has a function that detect the resistance of the deflection yoke coil to prevent the damage of the load which is produced by poor peeling.

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