• 제목/요약/키워드: Frequency Dependent Control

검색결과 244건 처리시간 0.04초

풍력발전단지의 효율적 운영을 위한 퍼지로직 기반 주파수 제어기 설계 (A Design for a Fuzzy Logic based Frequency Controller for Efficient wind Farm Operation)

  • 김세윤;김성호
    • 제어로봇시스템학회논문지
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    • 제20권2호
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    • pp.186-192
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    • 2014
  • Recently wind energy penetration into power systems has increased. Wind power, as a renewable energy source, plays a different role in the power system compared to conventional power generation units. As long as only single and small wind power units are installed in the power system, wind power does not influence power system operation and can easily be integrated. However, when wind power penetration reaches a significantly high level and conventional power production units are substituted, the impact of wind power on the power system becomes noticeable and must be handled. The connection of large wind turbines and wind farms to the grid has a large impact on grid stability. The electrical power system becomes more vulnerable to and dependent on wind energy production, and therefore there is an increased concern about the large wind turbines impact on grid stability. In this work, a new type of fuzzy logic controller for the frequency control of wind farms is proposed and its performance is verified using SimWindFarm toolbox which was developed as part of the Aeolus FP7 project.

공압제진대용 이중챔버형 공압스프링의 복소강성 모형화 (Amplitude-dependent Complex Stiffness Modeling of Dual-chamber Pneumatic Spring for Pneumatic Vibration Isolation Table)

  • 이정훈;김광준
    • 한국소음진동공학회논문집
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    • 제18권1호
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    • pp.110-122
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    • 2008
  • Pneumatic vibration isolator typically consisting of dual-chamber pneumatic springs and a rigid table are widely employed for proper operation of precision instruments such as optical devices or nano-scale equipments owing to their low stiffness- and high damping-characteristics. As environmental vibration regulations for precision instruments become more stringent, it is required to improve further the isolation performance. In order to facilitate their design optimization or active control, a more accurate mathematical model or complex stiffness is needed. Experimental results we obtained rigorously for a dual-chamber pneumatic spring exhibit significantly amplitude dependent behavior, which cannot be described by linear models in earlier researches. In this paper, an improvement for the complex stiffness model is presented by taking two major considerations. One is to consider the amplitude dependent complex stiffness of diaphragm necessarily employed for prevention of air leakage. The other is to employ a nonlinear model for the air flow in capillary tube connecting the two pneumatic chambers. The proposed amplitude-dependent complex stiffness model which reflects dependency on both frequency and excitation amplitude is shown to be very valid by comparison with the experimental measurements. Such an accurate nonlinear model for the dual-chamber pneumatic springs would contribute to more effective design or control of vibration isolation systems.

산업용 서보 구동 시스템을 위한 자동 P/PI 속도 제어기 설계 (Automatic P/PI Speed Controller Design for Industry Servo Drives)

  • 배상규;석줄기;김경태;이동춘
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제52권12호
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    • pp.616-623
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    • 2003
  • Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the quality of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, acceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically performed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

연속가변 ER 댐퍼의 제어 및 응답특성 (Control and Response Characteristics of a Continuously Variable ER Damper)

  • 최승복;최영태;박우철;정재천;서문석;여문수
    • 한국자동차공학회논문집
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    • 제4권6호
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    • pp.164-174
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    • 1996
  • This paper presents control and response characteristics of a continuously variable ER(electrorheological) damper for small-sized vehicles. The ER damper is devised and its governing equation of motion is derived from the bond graph model. The field-dependent yield shear stresses are distilled from experimental investigation on the Bingham property of the ER fluid. The distilled data are incorporated into the governing system model and, on the basis of this model, an appropriate size of the ER damper is manufactured. After evaluating the field-dependent damping performance of the proposed ER damper, the skyhook control algorithm is formulated to achieve desired level of the damping force. The controller is then experimentally implemented and control characteristics of the ER damper are presented in order to demonstrate superior controllability of the damping force. In addition, response characteristics of the damping force with respect to the electric field with fast on-off frequency are provided to show the feasibility of practical application.

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압전 작동기를 이용한 방향 제어 밸브의 동적 모델링 및 제어 (Dynamic Modeling and Control of Directional Control Valve Using Piezostack Actuator)

  • 전준철;한영민;구오흥;한승훈;최승복
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2012년도 추계학술대회 논문집
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    • pp.331-336
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    • 2012
  • This paper proposes a new type of high-frequency directional valve controlled by the piezostack actuator associated with displacement amplifier. As a first step, a dynamic model of directional valve which can operate at 200 Hz with a flow rate of 12 l/min is derived by considering pressure drop and flow force. As a second step, an appropriate piezostack is selected by considering actuation force as well as field-dependent displacement. Subsequently, in order to control spool displacement and flow rate a proportional-derivative (PD) controller is designed based on the $3^{rd}$-order valve system. Control performances such as sinusoidal trajectory tracking of the spool displacement in time domain are evaluated. In addition, the field-dependent flow rate is also presented to verify the required performance of the valve system.

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압전 작동기를 이용한 방향 제어 밸브의 동적 모델링 및 제어 (Dynamic Modeling and Control of Directional Control Valve Using Piezostack Actuator)

  • 전준철;한영민;구오흥;최승복
    • 한국소음진동공학회논문집
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    • 제22권10호
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    • pp.1020-1026
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    • 2012
  • This paper proposes a new type of high-frequency directional valve controlled by the piezostack actuator associated with displacement amplifier. As a first step, a dynamic model of directional valve which can operate at 200 Hz with a flow rate of 12 litter/min is derived by considering pressure drop and flow force. As a second step, an appropriate piezostack is selected by considering actuation force as well as field-dependent displacement. Subsequently, in order to control spool displacement and flow rate a proportional-derivative(PD) controller is designed based on the 3rd-order valve system. Control performances such as sinusoidal trajectory tracking of the spool displacement in time domain are evaluated. In addition, the field-dependent flow rate is also presented to verify the required performance of the valve system.

알코올 의존과 세로토닌 수송체 유전자 다형성의 연관 (Association of Serotonin Transporter Gene Polymorphism with Alcohol Dependence)

  • 손현균;최인근;채영규;최미란;김재환;양병환;김석현;성승모
    • 생물정신의학
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    • 제10권2호
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    • pp.159-167
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    • 2003
  • Objective:Under the hypothesis that 5-HTTLPR polymorphism plays some role in the susceptibility or vulnerability of some subgroup of alcohol dependence, associations of 5-HTTLPR polymorphism with alcohol dependence were examined. Method:This association analysis included 109 Korean alcohol dependent and 113 Korean control subjects. DNA of all subjects were genotyped for the biallelic functional polymorphism in the 5-HTTLPR. Considering the likelihood of heterogeneity in the alcohol dependence phenotype, alcohol dependent subjects were subgrouped by onset age, family history of alcohol dependence and severity of withdrawal symptoms. Results:There were no significant differences in the frequencies of either the 5-HTTLPR genotype or the short vs. long allele in alcohol dependent and control subjects. The frequency of the S allele and S-carrier (LS or SS genotype) was significantly increased in the early onset alcohol dependent subjects and the familial alcohol dependent subjects compared with that in the control subjects. Conclusion:The results suggest that the 5-HTT 'S' promoter polymorphism is associated with an increased susceptibility or vulnerability to develop early onset alcohol dependence and familial alcohol dependence, which characterize Cloninger's type 2 alcohol dependence.

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High Performance Adjustable-Speed Induction Motor Drive System Incorporating Sensorless Vector Controlled PWM Inverter with Auto-Tuning Machine-Operated Parameter Estimation Schemes

  • Soshin, Koji;Okamura, Yukiniko;Ahmed, Tarek;Nakaoka, Mutsuo
    • Journal of Power Electronics
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    • 제3권2호
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    • pp.99-114
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    • 2003
  • This paper presents a feasible development on a highly accurate quick response adjustable speed drive implementation fur general purpose induction motor which operates on the basis of sensorless slip frequency type vector controlled sine-wave PWM inverter with an automatic tuning machine parameter estimation schemes. In the first place, the sensorless vector control theory on the three-phase voltage source-fed inverter induction motor drive system is developed in slip frequency based vector control principle. In particular, the essential procedure and considerations to measure and estimate the exact stator and rotor circuit parameters of general purpose induction motor are discussed under its operating conditions. The speed regulation characteristics of induction motor operated by the three-phase voltage-fed type current controlled PWM inverter using IGBT's is illustrated and evaluated fur machine parameter variations under the actual conditions of low frequency and high frequency operations for the load torque. In the second place, the variable speed induction motor drive system, employing sensorless vector control scheme which is based on three -phase high frequency carrier PWM inverter with automatic toning estimation schemes of the temperature -dependent and -independent machine circuit parameters, is practically implemented using DSP-based controller. Finally, the dynamic speed response performances for largely changed load torque disturbances as well as steady state speed vs. torque characteristics of this induction motor control implementation are illustrated and discussed from an experimental point of view.

Roles of Nitric Oxide in Vestibular Compensation

  • Jeong, Han-Seong;Jun, Jae-Yeoul;Park, Jong-Seong
    • The Korean Journal of Physiology and Pharmacology
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    • 제7권2호
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    • pp.73-77
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    • 2003
  • The effects of nitric oxide on the vestibular function recovery following unilateral labyrinthectomy (UL) were studied. Sprague-Dawley male rats, treated with nitric oxide liberating agent sodium nitroprusside (SNP) and NOS inhibitor $N^G$-nitro-L-arginine methyl ester (L-NAME), were subjected to destruction of the unilateral vestibular apparatus, and then spontaneous nystagmus was observed in the rat. To explore the effects of nitric oxide on the neuronal excitability, whole cell patch clamp technique was applied on isolated medial vestibular nuclear neurons. The frequency of spontaneous nystagmus in SNP treated rats was lesser than that of spontaneous nystagmus in control animals. In contrast, pre-UL treatment with L-NAME resulted in a significant increase in spontaneous nystagmus frequency. In addition, SNP increased the frequency of spontaneous action potential in isolated medial vestibular nuclear neurons. Potassium currents of the vestibular nuclear neurons were inhibited by SNP. After blockade of calcium dependent potassium currents by high EGTA (11 mM) in a pipette solution, SNP did not inhibit outward potassium currents. 1H-[1,2,4] oxadiazolo [4,3-a] quinozalin-1-one (ODQ), a specific inhibitor of soluble guanylyl cyclase, inhibited the effects of SNP on the spontaneous firing and the potassium current. These results suggest that nitric oxide after unilateral labyrinthectomy would help to facilitate vestibular compensation by inhibiting calcium-dependent potassium currents through increasing intracellular cGMP, and consequently would increase excitability in ipsilateral vestibular nuclear neurons.

Differential cubature method for vibration analysis of embedded FG-CNT-reinforced piezoelectric cylindrical shells subjected to uniform and non-uniform temperature distributions

  • Madani, Hamid;Hosseini, Hadi;Shokravi, Maryam
    • Steel and Composite Structures
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    • 제22권4호
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    • pp.889-913
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    • 2016
  • Vibration analysis of embedded functionally graded (FG)-carbon nanotubes (CNT)-reinforced piezoelectric cylindrical shell subjected to uniform and non-uniform temperature distributions are presented. The structure is subjected to an applied voltage in thickness direction which operates in control of vibration behavior of system. The CNT reinforcement is either uniformly distributed or functionally graded (FG) along the thickness direction indicated with FGV, FGO and FGX. Effective properties of nano-composite structure are estimated through Mixture low. The surrounding elastic foundation is simulated with spring and shear constants. The material properties of shell and elastic medium constants are assumed temperature-dependent. The motion equations are derived using Hamilton's principle applying first order shear deformation theory (FSDT). Based on differential cubature (DC) method, the frequency of nano-composite structure is obtained for different boundary conditions. A detailed parametric study is conducted to elucidate the influences of external applied voltage, elastic medium type, temperature distribution type, boundary conditions, volume percent and distribution type of CNT are shown on the frequency of system. In addition, the mode shapes of shell for the first and second modes are presented for different boundary conditions. Numerical results indicate that applying negative voltage yields to higher frequency. In addition, FGX distribution of CNT is better than other considered cases.