• 제목/요약/키워드: Low speed operation

검색결과 831건 처리시간 0.025초

Dynamic Simulation of Pump-Storage Power Plants with different variable speed configurations using the Simsen Tool

  • Kruger, Klaus;Koutnik, Jiri
    • International Journal of Fluid Machinery and Systems
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    • 제2권4호
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    • pp.334-345
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    • 2009
  • Pumped storage power plants are playing a significant role in the contribution to the stabilization of an electrical grid, above all by stable operation and fast reaction to sudden load respectively frequency changes. Optimized efficiency and smooth running characteristics both in pump and turbine operation, improved stability for synchronization in turbine mode, load control in pump mode operation and also short reaction times may be achieved using adjustable speed power units. Such variable speed power plants are applicable for high variations of head (e.g. important for low head pump-turbine projects). Due to the rapid development of power semiconductors and frequency converter technology, feasible solutions can be provided even for large hydro power units. Suitable control strategies as well as clear design criteria contribute significantly to the optimal usage of the pump turbine and motor-generators. The SIMSEN tool for dynamic simulations has been used for comparative investigations of different configurations regarding the power converter topology, types of semiconductors and types of motor-generators including the coupling to the hydraulic system. A brief overview of the advantages & disadvantages of the different solutions can also be found in this paper. Using this approach, a customized solution minimizing cost and exploiting the maximum usage of the pump-turbine unit can be developed in the planning stage of new and modernization pump storage projects.

유도무선루프에 의한 자기부상열차 정보전송 시스템의 설계 (Design of MAGLEV Information Transmission System by Radio Inductive Loop)

  • 안상권;박석하;박정수;김종범;김양모
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제48권1호
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    • pp.42-47
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    • 1999
  • This paper presents the information transmission between on-board and ground-site in MAGLEV. considering safety and high speed operation and density operation, information transmission between them is necessary. Therefore it is necessary for transmission system to ensure high speed transmission, low error rate, massive information, and reliability of information. To provide above conditions, 1.1km signal line assembly was constructed and Frequency Shift Keying(FSK) modulation and Open System Interconnection(OSI) based high-level data link control(HDLC) protocol are applied. To modulate digital signal for transmission from ground-site to on-board, carrier frequency of 70kHz is used and 90khz is used for transmission from on-board to ground-site. Transmission speed is 2400bps for consideration of train speed, quantity of information, and data error rate. And this paper introduces information monitoring considering user interface and presents the method for an effective data transmission in MAGLEV which is now being tested and intends to provide for an intelligent train operation system in future.

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비대칭 Groove를 이용한 FDB 회전축의 기울기 보상 (Compensation of Inclined Rotating Axis Using Unsymmetric Groove Patterns)

  • 이남훈;한재혁;오동호;김철순;변용규;구자춘
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.582-585
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    • 2004
  • Most of hard disk drives currently employ fluid dynamic bearing (FDB) for their rotor support. Stiffness of the FDB is affected by many design factors such as bearing clearance, fluid viscosity, and rotational speed. For the high rotating speed HDDs stiffness of the rotor is normally high enough to accomodate load disturbances. However small form factor HDDs that are to be operated in low power consumption are often designed with low stiffness rotors. Although the low stiffness rotor clearly benefits low power operation, it could damage the entire motor structure or head disk interface even by a light mechanical load disturbance such as shock or vibration. In addition, since a single channel HDD does not provide gram load equilibrium in axial direction the rotor could be tilted and make a hard contact to stator. A non-symmetric groove pattern could successfully compensate the tilted rotor angle during operation.

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부분부하제어를 위한 스크류형 과급기 개발 (Development of a screw type super-charger for part load control)

  • 배재일;배신철
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.353-358
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    • 2001
  • Turbo-charging or Super-charging has been used to boost engine power for Gasoline Engine and Diesel Engine came to the world at the beginning of $20^{th}$ century. So far Turbo-Charger has enjoyed a high reputation in the charging filed for its technical advantages such as no demand of operation power from engine and an excellent charging effect in the event of a static operation at mid- and high engine speed. A mechanically driven Super-Charger, however, is now emerging in order to meet demands of the age of speed such as high engine power for a quick change of the driving mode - high engine torque even at low engine speed. Since Super-Charger needs driving power from engine, it cannot improve its relatively higher fuel consumption against that of Turbo-Charger. This negative point is still an obstacle to the wide use of Super-Charger. Super-Charger using Screw-type compressor which has already had a considerable base in air compressor market will fulfill this purpose of improving fuel consumption by minimizing operation power owing to no charging at idling or partially loading driving. This study aims to develop power control concept to achieve this minimization of operation power.

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고속화에 대응한 전차선로 설계 요소기술 (Design Essential Element Technology of Catenary System be in Correspondence with Speed-up)

  • 창상훈;김양수;박병수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 춘계학술대회 논문집 전기설비전문위원
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    • pp.75-78
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    • 2005
  • The decisive criteria to determine collection performance is the contact force between pantograph and catenary. The contact force consists of a static force and dynamic force related to vibration characteristics, train speed and etc. The low contact force leads to the loss of contact, and most countries regulate it below 1% at operation speed. This study presents a technical overview of criteria for collection performance of catenary system.

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부지연 회로를 내장한 200MHz 고속 16M SDRAM (A 200MHz high speed 16M SDRAM with negative delay circuit)

  • 김창선;장성진;김태훈;이재구;박진석;정웅식;전영현
    • 전자공학회논문지C
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    • 제34C권4호
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    • pp.16-25
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    • 1997
  • This paper shows a SDRAM opeating in 200MHz clock cycle which it use data interleave and pipelining for high speed operation. We proposed NdC (Negative DEaly circuit) to improve clock to access time(tAC) characteristics, also we proposed low power WL(wordline)driver circit and high efficiency VPP charge-pump circit. Our all circuits has been fabricated using 0.4um CMOS process, and the measured maximum speed is 200Mbytes/s in LvTTL interface.

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Characteristics of Non-Isolated OSAKA Converter -Characteristics of Three-Phase Soft-Switching Power Factor Corrected Converter for Large Scale Power Without Three-Phase Transformer-

  • Taniguchi, Katsunori;Shimomori, Wataru;Lee, Hyun-Woo
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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    • pp.1383-1386
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    • 2005
  • Non-isolated OSAKA Converter, which removes a three-phase transformer, is described in this paper. The converter switches once in every half cycle of an AC commercial power source. Therefore, it can solve many problems caused by the high frequency operation. The proposed converter achieves the soft-switching operation and the EMI noise can be reduced. In this circuit, the resonant capacitor, which is used for the soft-switching operation, is utilized for the improvement of an input current waveform. To achieve low cost and compact structure, non-isolated OSAKA converter removes a three-phase transformer of the OSAKA converter. By removing the three-phase transformer, three phase currents occur the interferences each other. To avoid the interference, a new switching method for non-isolated OSAKA converter is preposed. The converter can be constructed by the low-speed large power devices. The converter generates the low distorted input current waveforms with high power factor.

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저속 영역에서 직류 서어보 전동기의 속응성 제어에 관한 연구 (A Study On Fast Responce Control of DC Servo Motor at low Speed Region)

  • 윤병도;이홍배
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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    • pp.414-417
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    • 1988
  • This paper presents a study on the operation of a digitally controlled DC servo motor drive at low speed region. Two schemes aiming to improve the transient behavior of the speed control system are considered. The first scheme is the current positive feedback scheme to reduce the sensitivity of the system with respect to the load torque variations. The second one is the speed observer based on a motor model. Finally, the two schemes are studied by simulation and then verified experimetally using a prototype DC motor drive.

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가변속 왕복동 압축기의 급유 촉진기구 설계 (Design of Oil Supply Enhancement Device for a Variable Speed Reciprocating Compressor)

  • 김현진;이태진
    • 설비공학논문집
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    • 제15권1호
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    • pp.25-31
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    • 2003
  • This paper addresses an oil supply enhancement device to resolve a shortage of oil supply or no oil supply at all encountered at low speed operation for a variable speed reciprocating compressor used for household refrigerators. The oil supply enhancement device comprises a moving cylinder attached to the lower end of crankshaft and two of fluid diodes, each one at the inlet and outlet of the cylinder. Up-and-down movement of the cylinder against the lower end of the crankshaft together with the functioning of the two fluid diodes produces net oil flow from oil reservoir to inside the crankshaft. The experiment on the test bench has shown that enough oil supply into the oil feeding hole cu be made by using this device even at low speed range. Some analytical study has also been carried out to under-stand its oil supply mechanism.

저속 2행정 디젤엔진의 과도 비틀림 진동에 의한 축계 피로 강도에 관한 연구 (A Study on Shaft Fatigue Strength due to Torsional Vibrations in Two Stroke Low Speed Diesel Engines)

  • 이돈출;김상환
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 추계학술대회논문집
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    • pp.786-791
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    • 2006
  • Two stroke low speed diesel engines are mainly used for marine propulsion or power plant prime mover. These have many merits such as higher thermal efficiency, mobility and durability. However various annoying vibrations sometimes occur in ships or at the plant itself. Of these vibrations, torsional vibration is very important and it should be carefully investigated during the initial design stage for engine's safe operation. In this paper authors suggest a new estimation method of for shaft's can be calculated equivalently from accumulated fatigue cycles number due to torsional vibration. The 6S70MC-C($25,320ps{\times}91rpm$) engine for ship propulsion was selected as a case study, and the accumulated fatigue cycles numbers for shafting life time converted from the measured angular velocity and torsional vibration stress was calculated. This new method can be realized and confirmed in test model ship with two stroke low speed diesel engine.

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