• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1251-1258
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• 1999

The water level control of a steam generator in the unclear power plant is an important process. Most of the water level controllers of the actual plant are PID controllers. But they have limitations in appling for tracking the set point and getting rid of disturbances, so there are some defects to apply in the actual ground even though many research works represented the resolutions to solve it. In this paper, it is suggested that the established simple PID controller in low power has the ability to remove disturbances and trace the set-point, and then possesses the real-time self-tuning function according to the variety of moving peculiarity of a plant. This function realized by making use of fuzzy logic. PID parameters are formulated by a variable ${\alpha}$ and made it fluctuate by a fuzzy inference according to level error and level error change. This mechanism makes application of actual plant effective as well as taking advantage of improving the efficiency of water level controller by way of adding the function of self-tuning instead of replacing PID controller. The computer simulation of this scheme shows the improved performance compare to conventional PID controller.

• Journal of Power Electronics
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• 제16권1호
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• pp.190-204
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• 2016

An active front end (AFE) is required for a three-phase induction motor (IM) fed by a voltage source inverter (VSI), because of the increasing need to derive quality current from the utility end without sacrificing the power factor (PF). This study investigates a proportional-plus-integral (PI) controller based AFE topology that uses a super-lift converter (SLC). The significance of the proposed SLC, which converts rectified AC supply to geometrically proceed ripple-free DC supply, is explained. Variations in several power quality parameters in the intended IM drive for 0% and 100% loading conditions are demonstrated. A simulation is conducted by using MATLAB/Simulink software, and a prototype is built with a field programmable gate array (FPGA) Spartan-6 processor. Simulation results are correlated with the experimental results obtained from a 0.5 HP IM drive prototype with speed feedback and a voltage/frequency (V/f) control strategy. The proposed AFE topology using SLC is suitable for three-phase IM drives, considering the supply end PF, the DC-link voltage and current, the total harmonic distortion (THD) in supply current, and the speed response of IM.

• 전력전자학회논문지
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• 제7권4호
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• pp.332-338
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• 2002

토카막 장치의 초전도 코일에 사용되는 전원 공급장치는 초대형급(20kA) 직류 전원 공급기로서 빠른 전류제어 응답성과 매우 작은 정상상태 리플이 필수적이다. 특히 역전류 공급이 가능한 회생형 컨버터의 운전중 전류 방향이 바뀌는 순간에도 전류기준값을 잘 추종하는 것이 중요하다. 이러한 조건들을 만족시키기 위하여 입력측에 2중 출력($\Delta$, Y)를 갖는 변압기와 출력단에 상간변압기(interphase transformer, IPT)를 이용한 12펄스 싸이리스터 듀얼 컨버터를 설계, 제작하였다. 각 컨버터에서 출력되는 전류의 합이 부하전류 지령치를 따르도록 제어하는 동시에 차 전류의 평균값이 영이 되도록 함으로써 각 컨버터의 부하 분담율을 일정하게 하여 상간 변압기의 포화를 방지한다. 대전류 코일 전류 공급장치의 양방향 전류 제어 성능을 높이기 위하여 위상각 검출 및 게이팅 지연각 구현을 디지털화하고 컨버터 전류방향 정역절환시 초기 응답특성을 개선하는 방법을 제안하였다. 또한 시뮬레이션과 실부하 전류실험을 통해 제안된 제어기의 동작성능을 확인하였다.

• 전기학회논문지P
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• 제63권4호
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• pp.290-294
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• 2014

PID(Proportional, Integral, Derivative) controller is the most popular process controllers in nuclear power plants. The optimized parameter setting of the process controller contributes to the stable operation and the efficiency of the operating nuclear power plants. PID parameter setting is tuned when new process control systems are installed or current process control systems are changed. When the nuclear plant is shut down, a lot of PID tuning methods such as the Trial and Error method, Ultimate Oscillation method operation, Ziegler-Nichols method, frequency method are used to tune the PID values. But inadequate PID parameter setting can be the cause of the unstable process of the operating nuclear power plant. Therefore the results of PID parameter setting should be simulated, optimized and finally verified. This paper introduces the simulation method of PID tuning to optimize the PID parameter setting and confirms them of the actual PID controller in the operating nuclear power plants. The simulation method provides the accurate process modeling and optimized PID parameter setting of the multi-loop control process in particular.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1253-1260
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• 2022

This paper reports the control method for the core power of the China initiative Accelerator Driven System (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a proton accelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rod inside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. In order to continuously change the beam intensity, an adjustable aperture is considered to be used at the Low Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on the Proportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or the setting core power with the measured value. To evaluate the proposed control method, a CiADS core model is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably by adjusting the aperture size. The response time in the adjustment of the core power depends mainly on the adjustment time of the beam intensity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1314-1317
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• 1999

In this paper, we design an Adaptive Neuro-Fuzzy Inference System(ANFIS) Precompensator for the performance improvement of conventional proportional integral derivative (PID) controller that the governor system of power plant constantly maintains the load frequency of two-area power system. The ANFIS Precompensator is expressed as the membership functions of premise parameters and the linear combination of consequent parameters by Sugeno's fuzzy if-then rules using nonlinear input-output relation for the set point automatic modification maintaining conventional PID controller. The proposed compensation design technique is hoped to be satisfactory method overcome difficulty of exact modelling and arising problems by the complex nonlinearities of power system, and our design shows merit that is easily implemented by adding an ANFIS precompenastor to an existing PID controller without replacement.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.298-301
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• 1999

This paper presents a design technique based on the root locus method fur a class of $n^{th}$ order plants using PID (Proportional-Integral-Derivative) x (n-1) stage PD controller. It is intended to satisfy both transient and steady state response specifications. This controller can be used instead of a conventional PID controller for the higher order plants to obtain better performances. The controlled system is approximated as a stable and robust second order controlled system. Only adjusting the controller gain, the desired performances of the controlled system are satisfied. For the stable plant including the plant with small dead time, the controlled system is made robustly stable. In case of the unstable plant, when the controller gain is adjusted higher than the critical value, the unstable plant can also be made stable. Robustness properties given by this controller proposed in this paper have also been demonstrated by numerical examples.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.134-136
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• 2005

The author present a modified multi-loop algorithm Including feedforward for controlling a 55kW stepdown chopper in the power supply of Maglev The gains of the control algorithm were selected based on pole locations formulated from a prototype Bessel transfer function model. The design incorporate tradeoffs in DC-to-DC converter hard-ware para-meters and pole locations. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink.

• 한국산학기술학회논문지
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• 제10권12호
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• pp.3587-3593
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• 2009

최근 태양광 시스템에서는 기존의 태양광 시스템을 계통과 전원으로 상호 접속하는 것에 대한 연구에 관심이 모아지고 있다. 단상, 삼상 시스템에 관계없이 태양광 시스템에서 태양광 인버터는 계통연계 동작에 중요한 역할을 하기 때문에 전체 시스템에서 핵심요소로 고려된다. 태양광 인버터를 제어하기 위해서는 부하 전류 조절이 핵심요소 중 하나이다. 일반적으로 태양광 인버터에서 이용되는 PI 제어기는 정상상태 오차와 왜란에 취약하다는 단점을 가지고 있기 때문에 실제 시스템에 완벽하게 적용하기에는 무리가 있다. 특히, 이는 고주파영역에서의 PI와 PR 제어기의 성능을 비교해보면 알 수 있다. 이 논문에서 제시된 PR 제어기는 무한 이득을 교류 기본파 성분에 넣을 수 있기 때문에 PR 제어기는 회전좌표계의 PI 제어기에서 사용되는 디커플링 기법과 복잡한 변환 없이 제로 정상상태오차에 도달할 수 있다. 그렇기 때문에 이 논문에서는 PI 제어기를 대체하는 이론적 분석을 통해 PR 제어기를 설계하였다. 논문에 제시되어 있는 이론을 바탕으로 한 PR 제어기를 고정 소수점 연산방식의 32비트 마이크로컨트롤러 DSP320F2812를 기반으로 한 3kW 프로토타입 태양광 인버터에 적용, 평가하였다. 또한 태양광 인버터의 제어 성능을 시뮬레이션과 실험결과를 통하여 보여주고 검증하였다.

• 농업과학연구
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• 제50권4호
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• pp.773-784
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• 2023

In this study, we developed a dynamic model and steering controller model for an autonomous tractor and evaluated their performance. The traction force was measured using a 6-component load cell, and the rotational speed of the wheels was monitored using proximity sensors installed on the axles. Torque sensors were employed to measure the axle torque. The PI (proportional integral) controller's coefficients were determined using the trial-error method. The coefficient of the P varied in the range of 0.1 - 0.5 and the I coefficient was determined in 3 increments of 0.01, 0.05, and 0.1. To validate the simulation model, we conducted RMS (root mean square) comparisons between the measured data of axle torque and the simulation results. The performance of the steering controller model was evaluated by analyzing the damping ratio calculated with the first and second overshoots. The average front and rear axle torque ranged from 3.29 - 3.44 and 6.98 - 7.41 kNm, respectively. The average rotational speed of the wheel ranged from 29.21 - 30.55 rpm at the front, and from 21.46 - 21.63 rpm at the rear. The steering controller model exhibited the most stable control performance when the coefficients of P and I were set at 0.5 and 0.01, respectively. The RMS analysis of the axle torque results indicated that the left and right wheel errors were approximately 1.52% and 2.61% (at front) and 7.45% and 7.28% (at rear), respectively.