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Site Calibration for the Wind Turbine Performance Evaluation
Yoonsu Nam,Neungsoo Yoo,Jungwan Lee 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.12
The accurate wind speed information at the hub height of a wind turbine is very essential to the exact estimation of the wind turbine power performance testing. Several methods on the site calibration, which is a technique to estimate the wind speed at the wind turbine's hub height based on the measured wind data using a reference meteorological mast, are introduced. A site calibration result and the wind resource assessment for the TaeK wanRyung test site are presented using three-month wind data from a reference meteorological mast and the other mast temporarily installed at the site of wind turbine. Besides, an analysis on the uncertainty allocation for the wind speed correction using site calibration is performed.<br/>
DYNAMIC MODELING AND SYSTEM IDENTIFICATION FOR A MMAM CONTROLLED FLEXIBLE MANIPULATOR
Yoonsu Nam 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
For a high bandwidth, accurate end of arm motion control with good disturbance rejection, the Momentum Management Approach to Motion control(MMAM) is proposed. The MMAM is a kind of position control technique that uses inertial forces, applied at or near the end of arm to achieve high bandwidth and accuracy in movement and in the face of force disturbances.<br/> To prove the concept of MMAM, the end point control of a flexible manipulator is considered. For this purpose, a flexible beam is mounted on the x-y table, and the MMAM actuator is attached on the top of the flexible beam. A mathematical model is developed for the flexible beam being controlled by the MMAM actuator and slide base DC motor. A system identification method is applied to estimate some system parameters in the model which can not be determined because of the complexity of the mechanism. For the end point control of the flexible beam, the optimal linear output feedback control is introduced.
POSITION ESTIMATION USING COMBINED VISION AND ACCELERATION MEASUREMENT
Yoonsu Nam 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
There are several potential error sources that can affect the estimation of the position of an object using combined vision and acceleration measurements. Two of the major sources, accelerometer dynamics and random noise in both sensor outputs, are considered. Using a second-order model, the errors introduced by the accelerometer dynamics are reduced by the smaller value of damping ratio and larger value of natural frequency. A Kalman filter approach was developed to minimize the influence of random errors on the position estimate. Experimental results for the end-point movement of a flexible beam confirmed the efficacy of the Kalman filter algorithm.
Alleviating the Tower Mechanical Load of Multi-MW Wind Turbines with LQR Control
Yoonsu Nam,Pham Trung Kien,Yo-Han La 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6
This paper addresses linear quadratic regulation (LQR) for variable speed variable pitch wind turbines. Because of the inherent nonlinearity of wind turbines, a set of operating conditions is identified and then a LQR controller is designed for each of the operating points. The feedback controller gains are then interpolated linearly to get a control law for the entire operating region. In addition, the aerodynamic torque and effective wind speed are estimated online to get the gain-scheduling variable for implementing the controller. The potential of this method is verified through simulation with the help of MATLAB/Simulink and GH Bladed. The performance and mechanical load when using LQR are also compared with those obtained when using a PI controller.
Feedforward Pitch Control Using Wind Speed Estimation
Yoonsu Nam,Jeonggi Kim,Insu Paek,Young-Hwan Moon,Seog-Joo Kim,Dong-Joon Kim 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2
The dynamic response of a multi-MW wind turbine to a sudden change in wind speed is usually slow, because of the slow pitch control system. This could cause a large excursion of the rotor speed and an output power over the rated. A feedforward pitch control can be applied to minimize the fluctuations of these parameters. This paper introduces the complete design steps for a feedforward pitch controller, which consist of three stages, i.e. the aerodynamic torque estimation, the 3-dimensional lookup table for the wind seed estimation, and the calculation of the feedforward pitch amount. The effectiveness of the feedforward control is verified through numerical simulations of a multi-MW wind turbine.
Alleviating the Tower Mechanical Load of Multi-MW Wind Turbines with LQR Control
Nam, Yoonsu,Kien, Pham Trung,La, Yo-Han The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6
This paper addresses linear quadratic regulation (LQR) for variable speed variable pitch wind turbines. Because of the inherent nonlinearity of wind turbines, a set of operating conditions is identified and then a LQR controller is designed for each of the operating points. The feedback controller gains are then interpolated linearly to get a control law for the entire operating region. In addition, the aerodynamic torque and effective wind speed are estimated online to get the gain-scheduling variable for implementing the controller. The potential of this method is verified through simulation with the help of MATLAB/Simulink and GH Bladed. The performance and mechanical load when using LQR are also compared with those obtained when using a PI controller.
Strain Rate Self-Sensing for a Cantilevered Piezoelectric Beam
Nam, Yoonsu,Sasaki, Minoru The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.3
This paper deals with the analytical modeling, and the experimental verification of the strain rate self-sensing method using a hybrid adaptive filter for a cantilevered piezoelectric beam. The piezoelectric beam consists of two laminated lead zirconium titanates (PZT) on a metal shim. A mathematical model of the beam dynamics is derived by Hamilton's principle and the accuracy of the modeling is verified through the comparison with experimental results. For the strain rate estimation of the cantilevered piezoelectric beam, a self-sensing mechanism using a hybrid adaptive filter is considered. The discrete parts of this mechanism are realized by the DS1103 DSP board manufactured by dSPACE$\^$TM/. The efficacy of this method is investigated through the comparison of experimental results with the predictions from the derived analytical model.