• Title/Summary/Keyword: Operating Points

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STATIC CHARACTERISTICS OF A UREA-SCR SYSTEM FOR NOx REDUCTION IN DIESEL ENGINES

  • Nam, J.G.
    • International Journal of Automotive Technology
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    • v.8 no.3
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    • pp.283-288
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    • 2007
  • This paper presents the static characteristics of a urea-SCR system. The static characterization of the urea-SCR system was generated by sweeping urea flow rates at common engine torque/speed operating points. Several experiments were performed using engine operating points at different raw NOx emission levels, space velocities, and SCR catalyst temperatures. The recorded NOx emissions from the engine exhaust outlet and engine tailpipe are then compared. The urea-SCR static system results indicated that a $50{\sim}60%$ NOx conversion is achievable at most engine operating points using the stoichiometric $NH_3/NOx$ ratio, and a high 98% NOx conversion is possible by exceeding the stoichiometric $NH_3/NOx$ ratio. The effect of the pre-oxidation catalyst volume was also investigated and found to have a profound impact on experimental results, particularly the static NOx conversion.

Design of Vehicle Control Algorithm and Engine-generator Control for Drivability of Range-extended Electric Vehicle (주행거리 연장형 전기자동차의 차량제어 알고리즘 설계 및 운전성 확보를 위한 엔진 발전시스템 제어)

  • Park, Youngkug
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.6
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    • pp.649-659
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    • 2016
  • This paper describes control algorithm and control structure of vehicle control unit for range-extended electric vehicle equipped with engine-generator system, and specially presents methods which determine optimal operating points and decreases a vibration or a shock for operating the engine-generating system. The vehicle control algorithm is consisted of several parts which are sequence control, calculation of wheel demand torque, determination of operating points, and management of operating points and so vehicle controller has be made possible to efficiently manage calibration parameters. The control algorithm is evaluated by driving test modes, launching performance and operating engine-generator system and so on. In conclusion, this paper present methods for extending a mileage, improving a launching performance and reducing vibration or shock when the engine-generating system is starting or is stopping.

The Optimal Operating Points of Multiple UPFCs for Enhancing Power System Security Level (전력시스템 안전도 향상을 위한 다기 UPFC의 최적 운전점 결정)

  • 임정욱;문승일
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.8
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    • pp.388-394
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    • 2001
  • This paper presents how to determine the optimal operating points of Unified Power Flow controllers (UPFC) the line flow control of which can enhance system security level. In order to analyze the effect of these devices on the power system, the decoupled model has been employed as a mathematical model of UPFC for power flow analysis. The security index that indicates the level of congestion of transmission line has been proposed and minimized by iterative method. The sensitivity of objective function for control variables of and UPFC has been derived, and it represents the change in the security index for a given set of changes in real power outputs of UPFC. The proposed algorithm with sensitivity analysis gives the optimal set of operating points of multiple UPECs that reduces the index or increases the security margin and Marquart method has been adopted as an optimization method because of stable convergence. The algorithm is verified by the 10-unit 39-bus New England system that includes multiple FACTS devices. The simulation results show that the power flow congestion can be relieved in normal state and the security margin can be guaranteed even in a fault condition by the cooperative operation of multiple UPECs.

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Investigation on the Turbulent Flow-Field of a Small-size Axial Fan with Different Operating Points (운전점이 다른 소형 축류홴의 난류 유동장 고찰)

  • Kim, J.K.
    • Journal of Power System Engineering
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    • v.12 no.5
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    • pp.40-47
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    • 2008
  • The turbulent flow characteristics around a small-size axial fan(SSAF) for a refrigerator are strongly dependent upon the operating points. Four operating points such as $\phi$ =0.1, 0.18, 0.25 and 0.32 were adopted in this study to investigate three-dimensional turbulent flow characteristics around the SSAF by using a fiber-optic type Laser Doppler Anemometer(LDA) system. Downstream mean velocity profiles of the SSAF along the radial distance show that axial and tangential velocity components exist predominantly, except $\phi$ = 0.1, and have a maximum value at $r/R{\fallingdotseq}0.8$, but radial velocity component having a relatively small value only turns flow direction to the outside or the central part of the SSAF. The turbulent intensity shows that the radial component exists most greatly after $r/R{\fallingdotseq}0.5$. Downstream turbulent kinetic energy at $\phi$ = 0.25 and 0.32 together has the largest peak value at $r/R{\fallingdotseq}0.9$.

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Design of Linear Pitch Controller in Wind Turbine under the condition of Varying Operating Points (동작점 변화 조건에서의 풍력터빈 선형 피치제어기 설계)

  • Cheon, Jongmin;Kim, Choonkyoung;Lee, Joohoon;Hong, Jitae;Kwon, Soonman
    • 한국신재생에너지학회:학술대회논문집
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    • pp.40.1-40.1
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    • 2011
  • This paper presents a pitch controller which can hold output power constant at the rated value. Although wind turbine contains complicated nonlinearities, its behaviour within a certain operating range of a point can be approximated by that of a linear model. By doing so, we can apply rather simple and systematic linear control techniques such as PID and LQR(Linear Quadratic Regulator) to design a linear pitch controller. Because these linear controllers are valid only in a sufficiently small range around an operating point, linearized wind turbine model under the condition of varying wind speed needs a linear pitch controller can achieve the aims of tracking the rated rotor rotational speed. We propose an improved linear pitch controller taking each merit of LQR and PI controller under the condition of varying operating points in this paper.

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A Study on the Superheat Control of a Tandem-type Airconditioner by Using a Variable Speed Outdoor Fan (변속실외기펜을 사용한 텐텀형냉방기의 과열도제어에 관한 연구)

  • Kim, Jae-Hyun;Han, Do-Young
    • Proceedings of the SAREK Conference
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    • pp.474-479
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    • 2005
  • For the safe operation of an air conditioner, the liquid car η 'over to compressors should be minimized and compressors should be operated in the specified region of suction and discharge pressures recommended by compressor manufactures. In this study, a capillary assisted tandem-type airconditioner was considered. A variable speed outdoor fan was used to control operating points of the system. Test results showed the possibilities to move system operating points to the safe region by controlling the speed of an outdoor fan.

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Distributed Control of the Arago's Disc System with Gain Scheduler

  • Ibrahim, Lateef Onaadepo;Choi, Goon-Ho
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.3
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    • pp.25-30
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    • 2017
  • Arago's disk system consists of a speed controller of the DC motor (inner loop controller) and a position controller of the magnetic bar angle (main controller), which are implemented by the design of the PI and PID controller, respectively. First, we analyzed the nonlinear characteristics of the Arago disk system and found the operating point range of three locations as a result. In this paper, a gain scheduler method was applied to guarantee a constant control performance in the range of $0{\sim}130^{\circ}C$, and a structure to change the controller according to the control reference value based on the previously obtained operating points was experimentally implemented. The Distributed Control Systems (DCS) configuration using the Controller Area Network (CAN) was used to verify the proposed method by improving the operational efficiency of the entire experimental system. So, simplicity of the circuit and easy diagnosis were achieved through a single CAN bus communication.

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Speed Control of Marine Diesel Engines Using Fuzzy Scheduling (퍼지게인 스케줄링을 이용한 선박용 디젤기관의 속도제어)

  • 유성호
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.1-5
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    • 2000
  • The conventional PID controller has been extensively used to speed control of marine diesel engines. However one of drawbacks is that its control performance can be degraded if the parameters are fixed on whole operating points. In this paper a scheme for integrating PID control and the fuzzy technique is presented to control speed of a marine diesel engine on whole operating points. At first the PID controller is designed at each speed mode whose parameters are optimally adjusted using a genetic algorithm, Then fuzzy "if-then" rules combine the controllers as a consequence part. To demonstrate the effectiveness of the proposed fuzzy controller a set of simulation works on a marine diesel engine are carried out.rried out.

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Evaluation of Fuel Economy for a Parallel Hybrid Electric Vehicle

  • Park, Dookhwan;Kim, Hyunsoo
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1287-1295
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    • 2002
  • In this work, the fuel economy of a parallel hybrid electric vehicle is investigated. A vehicle control algorithm which yields operating points where operational cost of HEV is minimal is suggested. The operational cost of HEV is decided considering both the cost of fossil fuel consumed by an engine and the cost of electricity consumed by an electric motor. A procedure for obtaining the operating points of minimal fuel consumption is introduced. Simulations are carried out for 3 variations of HEV and the results are compared to the fuel economy of a conventional vehicle in order to investigate the effect of hybridization. Simulation results show that HEV with the vehicle control algorithm suggested in this work has a fuel economy 45% better than the conventional vehicle if braking energy is recuperated fully by regeneration and idling of the engine is eliminated. The vehicle modification is also investigated to obtain the target fuel economy set in PNGV program.

A Method to Define Steady-State Curves for Variable-Speed Variable-Pitch Wind Turbine (가변속도-가변피치 풍력터빈의 정상상태 곡선 결정 방법)

  • Lim, Chae-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.11
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    • pp.894-899
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    • 2009
  • Aerodynamic power and torque of wind turbine are highly nonlinear and its operation mode depends on control strategies. Therefore, it is essential to define steady-state curves for the purpose of control and operation of wind turbine system. The steady-state curves of wind turbine can be defined by determining its operating points. In this paper, an algorithm to determine operating points of variable-speed variable-pitch wind turbine is presented on the basis of pitch-to-feather control strategy. And this algorithm is applied to obtain steady-state curves for an 1.5MW wind turbine.