• Proceedings of the IEEK Conference
• /
• 2003.07d
• /
• pp.1295-1298
• /
• 2003

The steam generator level in a PWR is very difficult to control particularly at low power. And the constant control gain and time value are not adaptive in steam generator level controller. In normal operation constant control gain and time value have no problem. But there is problem at low power. So variable control gains based on the temperature are required. The best control gain is decided by the experienced knowledge. A fuzzy gain tuner is used for the gain tuning. In the design of fuzzy gain-tuner processing, the experienced knowledge is employed for making fuzzy rules.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.3
• /
• pp.93-101
• /
• 2016

This study presents a simple genetic algorithm to systematically design a PID controller for a hydraulic positioning system operated by a proportional solenoid valve. The inverse dead-zone compensator with nonlinear characteristics is used to cancel out the dead-zone phenomenon in the hydraulic system. The object function considering overshoot, settling time, and control input is adopted to search for optimal PID gains. The designed PID controller is compared with the LQG/LTR controller to check the performance of the hydraulic positioning system in the time and frequency domains. The experimental results show that the hydraulic servo system with the proposed PID controller responds effectively to the various types of reference input.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.10
• /
• pp.1487-1493
• /
• 2013

A new simple control method for active power filter, which can realize the complete compensation of harmonics is proposed. In the proposed scheme, a model-based digital current control strategy is presented. The proposed control system is designed and implemented in a form referred to as internal model control structure. This method provides a convenient way for parameterizing the controller in term of the nominal system model, including time-delays. As a result, the resulting controller parameters are directly set based on the power circuit parameters, which make tuning of the controllers straightforward task. In the proposed control algorithm, overshoots and oscillations due to the computation time delay is prevented by explicit incorporating of the delay in the controller transfer function. In addition, a new compensating current reference generator employing resonance model implemented by a DSP(Digital Signal Processor) is introduced. Resonance model has an infinite gain at resonant frequency, and it exhibits a band-pass filter. Consequently, the difference between the instantaneous load current and the output of this model is the current reference signal for the harmonic compensation.

• Journal of Power Electronics
• /
• v.18 no.5
• /
• pp.1369-1379
• /
• 2018

In this paper, a model predictive torque control (MPTC) without the use of a weighting factor for surface mounted permanent-magnet synchronous machine (SPMSM) drive systems is presented. Firstly, the desired voltage vector is predicted in real time according to the principles of deadbeat torque and flux control. Then the sector of this desired voltage vector is determined. The complete enumeration for testing all of the feasible voltage vectors is avoided by testing only the candidate vectors contained in the sector. This means that only two voltage vectors in the sector need to be tested for selecting the optimal voltage vector in each control period. Thus, the calculation time can be reduced when compared with the conventional enumeration method. On the other hand, a novel cost function that only includes the dq-axis voltage errors between the desired voltage and candidate voltage is designed to eliminate the weighting factor used in the conventional MPTC. Thus, the control complexity caused by the tuning of the weighting factor is effectively decreased when compared with the conventional MPTC. Simulation and experimental investigation have been carried out to verify the proposed method.

• International Journal of Precision Engineering and Manufacturing
• /
• v.8 no.4
• /
• pp.22-26
• /
• 2007

We describe a new way of implementing absolute displacement measurements by exploiting the optical comb of a femtosecond pulse laser as a wavelength ruler, The optical comb is stabilized by locking both the repetition rate and the carrier offset frequency to an Rb clock of frequency standard. Multiwavelength interferometry is then performed using the quasi-monochromatic beams of well-defined generated wavelengths by tuning an external cavity laser diode consecutively to preselected light modes of the optical comb. This scheme of wavelength synthesizing allows the measurement of absolute distances with a high precision that is traceable to the definition of time. The achievable wavelength uncertainty is $1.9{\times}10^{-10}$, which allows the absolute heights of gauge blocks to be determined with an overall calibration uncertainty of 15 nm (k = 1). These results demonstrate a successful industrial application of an optical frequency synthesis employing a femtosecond laser, a technique that offers many possibilities for performing precision length metrology that is traceable to the well-defined international definition of time.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.8
• /
• pp.1457-1462
• /
• 2009

This paper proposes a compensating algorithm for the secondary voltage of a coupling capacitor voltage transformer (CCVT) in the time domain by considering the hysteresis characteristics of the core. The proposed algorithm estimates the three error terms i.e. the voltage across the secondary winding parameters, the voltage across the primary winding parameters, and the voltage across the capacitor and the tuning reactor. These three terms are added to the measured secondary voltage to obtain the correct voltage. The algorithm reduces the errors of the CCVT significantly both in the steady state and during a fault. The performance of the algorithm is verified under the various fault conditions by varying the fault distance, the fault inception angle, and the fault impedance with the EMTP generated data. Test results clearly indicate that the algorithm can increase the accuracy of a CCVT significantly under the fault conditions as well as in the steady state. The algorithm helps improve the performance of a protection relay or a metering device.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.5
• /
• pp.771-780
• /
• 2004

The demands of users have become variety and diversification by the conversion of application to Web environment from C/S(Client/Server) enviroment as well as by the development of application which puts into practie an information technology with the advance of internet basic technology. Therefore if it attempt to satisfy their all demands, the services like a real time batch processing are faced with a difficult obstacle that the limited existing system cannot manage. Finally it is come to a conculsion that the extension of system or the induction of new system is necessary in order to solve this problem according to a ragular tuning and an examination about infra of web environment. This thesis intends to propose about inter- relation and improvement plan as well as considerable facts in case of the introduction of system through the efficiency analysis process of the system.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.51 no.8
• /
• pp.352-359
• /
• 2002

A neuro-fuzzy controller has some problems that he difficulty of tuning up the membership function and fuzzy rules, long time of inferencing and defuzzifying compare to PID. Also, the fuzzy controller's own defect as a PD controller has. In this study, it is proposed two methods to solve these problems. The first method is that inner fuzzy rules are tuned up automatically by the back propagation learning according to error patterns. And the second method is a new type defuzzification method that shorten the calculation time of an inferencing and a defuzzifying. In this study, it is designed the new type neuro-fuzzy controller that improves the fast response and the stability of a system by using the proposed methods. And, the designed controller is named EPLNFC(Error pattern Learning Neuro-Fuzzy Controller). To evaluate the fast response and the stability of EPLNFC designed in this study, EPLNFC is applied to a speed control of a DC motor and AC motor.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.6
• /
• pp.744-752
• /
• 1999

In this paper, we studied the response characteristics of $\alpha$, $\beta$ separated type, combined type, PI typed, and feedforward type in 2DOF-PID controller through the simulation and the experiments designed with the multivariable flow control system. The parameters $\alpha$ and $\beta$ give an affect to characteristics of controller in separated type but $\gamma$ does not give an affect to the characteristics of 2-DOF PID. The more $\beta$ increases, the more overshoot decreases and especially, in case of PI type represent clearly. The $\alpha$, $\beta$ separated type has a very small overshoot and its magnitudes in 2-DOF PID onctroller increases in order of $\alpha$, $\beta$ combined type, PI type, feedforward type, conventional type. The response characteristics of simulation are similar to that of experiments but the experimental characteristics in the multivariable flow control system has the delayed response. The time delay of response in experiments depends on 2-DOF parameter $\alpha$, $\beta$, $\gamma$ and the overshoot increase as the $\alpha$, $\beta$, $\gamma$ increase. So, we can have a satisfactory response by tuning D gain.

• Nuclear Engineering and Technology
• /
• v.41 no.1
• /
• pp.125-134
• /
• 2009

This paper presents details on a tube inspection robotic system and a positioning method of the robot for a steam generator (SG) in nuclear power plants (NPPs). The robotic system is separated into three parts for easy handling, which reduces the radiation exposure during installation. The system has a supporting leg to increase the rigidity of the robot base. Since there are several thousands of tubes to be inspected inside a SG, it is very important to position the tool of the robot at the right tubes even if the robot base is positioned inaccurately during the installation. In order to obtain absolute accuracy of a position, the robot kinematics was mathematically modeled with the modified DH(Denavit-Hartenberg) model and calibrated on site using tube holes as calibration points. To tune the PID gains of a commercial motor driver systematically, the time delay control (TDC) based gain tuning method was adopted. To verify the performance of the robotic system, experiments on a Framatomes 51B Model type SG mockup were undertaken.