• Title/Summary/Keyword: Input power estimation

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Flicker Estimation for Wind Turbine Systems using SVR (SVR을 이용한 풍력 발전 시스템의 플리커 추정)

  • Van, Tan Loung;Nguyen, Thanh Hai;Kim, Ki-Hong;Lee, Dong-Choon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.15 no.4
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    • pp.309-318
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    • 2010
  • This paper presents a simulation model based on support vector regression (SVR) for flicker estimation emitted from the wind turbines. For the SVR training, the voltage variation and flicker level are selected as input and output, respectively. Through the off-line training, the relationship between the voltage variation and flicker level is derived. The required amount of data for the flicker measurement is decreased and its proessing time is also reduced. The simulation and experiment results have shown that the flicker estimation is performed accurately.

Input-Output Feedback Linearization of Sensorless IM Drives with Stator and Rotor Resistances Estimation

  • Hajian, Masood;Soltani, Jafar;Markadeh, Gholamreza Arab;Hosseinnia, Saeed
    • Journal of Power Electronics
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    • v.9 no.4
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    • pp.654-666
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    • 2009
  • Direct torque control (DTC) of induction machines (IM) is a well-known strategy of these drives control which has a fast dynamic and a good tracking response. In this paper a nonlinear DTC of speed sensorless IM drives is presented which is based on input-output feedback linearization control theory. The IM model includes iron losses using a speed dependent shunt resistance which is determined through some effective experiments. A stator flux vector is estimated through a simple integrator based on stator voltage equations in the stationary frame. A novel method is introduced for DC offset compensation which is a major problem of AC machines, especially at low speeds. Rotor speed is also determined using a rotor flux sliding-mode (SM) observer which is capable of rotor flux space vector and rotor speed simultaneous estimation. In addition, stator and rotor resistances are estimated using a simple but effective recursive least squares (RLS) method combined with the so-called SM observer. The proposed control idea is experimentally implemented in real time using a FPGA board synchronized with a personal computer (PC). Simulation and experimental results are presented to show the capability and validity of the proposed control method.

On the Local Identifiability of Load Model Parameters in Measurement-based Approach

  • Choi, Byoung-Kon;Chiang, Hsiao-Dong
    • Journal of Electrical Engineering and Technology
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    • v.4 no.2
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    • pp.149-158
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    • 2009
  • It is important to derive reliable parameter values in the measurement-based load model development of electric power systems. However parameter estimation tasks, in practice, often face the parameter identifiability issue; whether or not the model parameters can be estimated with a given input-output data set in reliable manner. This paper introduces concepts and practical definitions of the local identifiability of model parameters. A posteriori local identifiability is defined in the sense of nonlinear least squares. As numerical examples, local identifiability of third-order induction motor (IM) model and a Z-induction motor (Z-IM) model is studied. It is shown that parameter ill-conditioning can significantly affect on reliable parameter estimation task. Numerical studies show that local identifiability can be quite sensitive to input data and a given local solution. Finally, several countermeasures are proposed to overcome ill-conditioning problem in measurement-based load modeling.

Design of a motion estimator for MPEG-2 video encoder using array architecture (어레이 구조를 이용한 MPEG-2 비디오 인코더용 움직임 예측기 설계)

  • 심재술;박재현;주락현;김영민
    • Journal of the Korean Institute of Telematics and Electronics C
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    • v.34C no.7
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    • pp.28-37
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    • 1997
  • In this paper, we designed a motion estimator for MPEG-2 video coder using VHDL. Motion estimation is indispensable for encoding MPEG 2 video. Motion estimation takes over 50% computation power of video encoding 37 frames per second and is suitable for real-time processing. The number of data accesses for computation is fewer than 2 times compared with that of old one. This makes slower memory module available. We minimize input pins to migrate input data through PEs. This processor can compute various motio estimation modes at one calculation that is supported by MPEG-2 video standard. Also independent control architecture makes this processor a single processor or a sub module in amultimedia chip.

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Cooperative Synchronization and Channel Estimation in Wireless Sensor Networks

  • Oh Mi-Kyung;Ma Xiaoli;Giannakis Georgios B;Park Dong-Jo
    • Journal of Communications and Networks
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    • v.7 no.3
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    • pp.284-293
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    • 2005
  • A critical issue in applications involving networks of wireless sensors is their ability to synchronize, and mitigate the fading propagation channel effects. Especially when distributed 'slave' sensors (nodes) reach-back to communicate with the 'master' sensor (gateway), low power cooperative schemes are well motivated. Viewing each node as an antenna element in a multi-input multi-output (MIMO) multi-antenna system, we design pilot patterns to estimate the multiple carrier frequency offsets (CFO), and the multiple channels corresponding to each node-gateway link. Our novel pilot scheme consists of non-zero pilot symbols along with zeros, which separate nodes in a time division multiple access (TDMA) fashion, and lead to low complexity schemes because CFO and channel estimators per node are decoupled. The resulting training algorithm is not only suitable for wireless sensor networks, but also for synchronization and channel estimation of single- and multi-carrier MIMO systems. We investigate the performance of our estimators analytically, and with simulations.

Capacitance Estimation of DC-Link Capacitors of PWM Converters using Input Current Injection (입력전류 주입을 이용한 PWM 컨버터의 직류 커패시터 용량 추정)

  • Lee Kang-Ju;Lee Dong-Choon;Seok Jul-Ki
    • Proceedings of the KIPE Conference
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    • 2002.11a
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    • pp.125-128
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    • 2002
  • In this paper, a novel on-line do capacitance estimation method for the PWM converter is proposed. At no load, Input current at a low frequency is injected, which causes do voltage ripple. With the ac voltage and current ripple components of the dc side, the capacitance can be calculated. Experimental result shows that the estimation error is less than $2\%$.

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Estimation and Application of Turbulent Flow-Induced Input Power for Vibrational Power Flow Analysis (진동파워흐름해석을 위한 난류흐름에 의한 입력파워 추정 및 적용)

  • Lim, Gu-Sub;Hong, Suk-Yoon;Park, Young-Ho;Choi, Young-Dal;Joung, Tea-Seok
    • Special Issue of the Society of Naval Architects of Korea
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    • 2008.09a
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    • pp.96-105
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    • 2008
  • Turbulent flow-induced vibrations generate the structural fatigue and noise problems. In this paper, using Corcos, Smol' yakov-Tkachenko, Ffowcs Williams and Chase models, the input power generated by distributed fluid force is predicted for power flow analysis (PFA) of turbulent flow-induced vibration. Additionally, the Fast Fourier Transform (FFT) is used to raise the calculation efficiency PFA results obtained are compared with the classical modal solutions for verifications. Analytic results using the fluid models show good agreements with those of modal analysis, respectively.

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Development of Durability Estimation and Design Systems of Worm Gears (웜기어의 강도평가 및 설계시스템 개발에 관한 연구)

  • Jeong, Tae Hyeong;Baek, Jae Hyeop
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.216-216
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    • 1997
  • We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.

A New Unified System of Acoustic Echo and Noise Suppression Incorporating a Novel Noise Power Estimation (새로운 잡음전력 추정 기법을 적용한 음향학적 반향 및 배경잡음 제거 통합시스템)

  • Park, Yun-Sik;Chang, Joon-Hyuk
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.7
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    • pp.680-685
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    • 2009
  • In this paper, we propose a efficient noise power estimation technique for an integrated acoustic echo and noise suppression system in a frequency domain. The proposed method uses speech absence probability (SAP) derived from the microphone input signal as the smoothing parameter updating noise power to reduce the noise power estimation error resulted from the distortions in the unified structure where the noise suppression (NS) operation is placed after the acoustic echo suppression (AES) algorithm. Therefore, in the proposed approach, the smoothing parameter based on SAP derived from the input signal instead of echo-suppressed signal should stop updating noise power estimates during the distorted noise spectrum periods. The performance of the proposed algorithm is evaluated by the objective test under various environments and yields better results compared with the conventional scheme.

The Control of Single Phase Power Factor PWM converter using Reduced-Order Luenberger Observer (축소차원 Luenberger 관측기를 이용한 단산 PWM 컨버터의 고역률 제어)

  • 양이우;이용근;김영석
    • Proceedings of the KIPE Conference
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    • 1999.07a
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    • pp.485-488
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    • 1999
  • In this paper, a current control system for single phase PWM AC/DC converter without the source voltage sensors is proposed. The sinusoidal input current and unity effective power factor are realised based on the estimated source voltage in the controller. The estimation of source voltage is performed by the reduced-order Luenberger observer using actual currents. The estimated source voltage is used to accomplish unity power factor. The proposed method is proved by experiments.

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