• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.374-378
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• 2014

PID control method usually has problems of overshoot and oscillation in high order control system, therefore, it is important to improve the control method so as to reduce the overshoot and oscillation. Based on MATLAB simulation, a permanent magnet (PM) DC servomotor control system is studied in this paper. The motor is modeled according to the universal motor theory, and with the help of the fourth order Ronge-Kutta method, its speed control is simulated and compared between two different dual closed-loops PWM control methods. This case study helps undergraduate students to better understand theories related to electrical engineering, such as electrical machinery, power electronics and control theory, as well as digital solution of state equations.

• Nuclear Engineering and Technology
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• 제38권7호
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• pp.657-664
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• 2006

The problem of reactivity oscillations for a point reactor constitutes an interesting aspect of nuclear reactor physics and its solution may give important information for dynamic and safety assessments. The present paper considers the problem of a reactivity oscillation for a source-driven system which involves some specific aspects that introduce significant differences with respect to the source-free situation. Assuming a square-wave shape for the reactivity insertion, the solution is derived by a fully analytical approach. The conditions for stability and instability can be identified in a straightforward way by directly studying the stationarity of the power response. Numerical results presented allow to discuss the role of the system kinetic parameters and of the time-shape of the reactivity wave.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.127-137
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• 2003

논문에서는 대규모 계통의 미소신호안전도 평가 및 해석을 위해 고유치 감도/perturbation 이론에 근거한 상정사고 지표를 제안하였으며 이를 실제 계통에 적용한 결과를 기술하였다. 선로정수와 제어기점수에 대한 미소신호 안정도 상정사고 지표를 제시하였고 이로부터 심각한 저주파진동 문제를 발생할 수 있는 파라메타들을 선택하였다. 또한 각 발전기의 발전량 증감에 대한 고유치 변화로부터 미소신호안정도 상정사고를 일으킬 수 있는 발전기들을 선택하였다. 이 논문에서는 모든 결과들을 2000년 KEPCO 실계통의 시간영역해석과 비교 검증하여 제안한 미소신호안정도 상정사고 해석법이 정확함을 확인하였다.

• 조명전기설비학회논문지
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• 제15권5호
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• pp.81-89
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• 2001

전력 계통 안정화 장치는 전력시스템에 외란이 발생했을 때 저주파수 동요현상을 효과적으로 저감하는 역할을 한다. 본 논문은 제주-해난 HVDC로 연계된 전력시스템에 설치된 PSS의 적정 파라메커 선정이론을 다루었다. 사용한 알고리즘은 위상지연을 적절한 극좌표 이동법으로 보상하고 설정된 댐핑계수가 되도록 이득계수를 구하는 방법이다. PSS 효과를 검증하기 위해 동태 및 과도안정도를 PSS 설치 전과 후로 비교하였다. MATLAB을 근거로 한 PST 프로그램을 사용하여 사례연구 시스템에 적용한 시뮬레이션 결과는 PSS를 설치하므로써 전력시스템이 안정화되어 만족할 만큼의 댐핑효과를 보았다.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.378-384
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• 2005

This paper proposes a new series and parallel Sin+Cos PSS (power system stabilizer) for the purpose of improving the existing PSS1A's performance. The purpose of the PSS is to enhance the damping of power system oscillations through injection of auxiliary signals for an excitation control terminal. The proposed series and parallel Sin+Cos PSS is connected adding the Sin+Cos terms additionally with the serial and parallel connection in a conventional PSS1A. The proposed controller is aimed at considering the damping of oscillation when it changes parameter fluctuations or operational load variations in a power system. The electric power system used is the KEPCO system and the voltage of the power transmission line is 154kV and 345kV. The PSCAD/EMTDC package is used to authorize the effect of the proposed controller. Simulations were shown by and compared with the waveforms for frequency, voltage and electric power.

• 대한전기학회논문지:전력기술부문A
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• 제51권7호
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• pp.317-326
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• 2002

In this paper, a methodology for optimal PI supplementary controller using the modified genetic algorithm has been proposed to the oscillation damping in HDVC transmission system. These study processes are summarized as the formulation for load flow calculation in HVDC transmission system with SVC, the investigations on the basic control in HVDC system, the mathematical modeling for dynamic characteristics analyses, and the optimal design of MGA based PI controller generation the supplementary control signal of SVC. Its properties were verified through a series of computer simulations including dynamic stability. It means that the application of MGA-PI controller in HVDC transmission system can contribute the propriety to the improvement of the stability in HVDC transmission system and the design of MGA-OI controller has been proved indispensible when applied to HVDC transmission system.

• Nuclear Engineering and Technology
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• 제22권4호
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• pp.371-379
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• 1990

제논의 공간적인 진동은 원자로의 운전에 지장을 초래할 수 있다. 본 연구에서는 가압경수로에서의 제논에 의한 불안정성을 분석하기 위하여, 보다 일반적이고 다중입력/다중출력 계통에 적합한 일반화된 Nyquist조건을 사용하는 진동수위주의 기술을 적용하였다. 또한 모드전개 방법에 의하여 선형화된 중성자속을 구했다. 이 모형으로 출력 준위, 제어봉 위치, 그리고 평균 노심 연소도둥의 노물리 변수의 변화에 따른 영광 1호기의 제논에 대한 축방향 안정성을 조사하였다. 결과로는, 출력 준위의 증가나 제어봉 삽입의 증가는 안정성을 저해하는 효과를 가져오고, 연소도가 증가할 수록 불안정한 것으로 나타났다.

• 한국음향학회지
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• 제3권1호
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• pp.9-15
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• 1984

Thermoacoustic oscillation induced by a heater in a tube with air current is studied theoretically. Linearized perturbation equations are derived in dimensionless form under the assumption that the system is one dimensional. The equation to predict the acoustic power generation from a heating surface is derived and calculated by solving differential equations numerically. The effect of the mean velocity of the air current is illustrated. The energy conversion mechanism is shown by pressure-volume diagram like a heat engine.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.93-95
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• 2002

This paper presents the design of a Unified Power Flow Controller(UPFC) for enhancing the small signal voltage stability in the multi-machine power systems. Recently a lot of attention has been paid to the subject of dynamic stability. The paper deals with analysis of eigenvalue sensitivities with respect to parameters of UPFC Controller. The series branch of the UPFC is designed to damp the power oscillation during transients, while the shunt branch aims at maintaining the bus voltage. Comprehensive time-domain simulation studies using Pss/E show that the proposed robost UPFC controller can enhance the small signal stability efficiently in spite of the variations of power system operating conditions.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.459-462
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• 2006

In this study, the characteristic of a vane pump of an automative power steering system is numerically analyzed. The vane pump changes the energy level of operation fluid by converting mechanical input power to hydraulic output. To simulate this mechanism, moving mesh technique is adopted. As a result, the flow rate and pressure are obtained by numerical analysis. The flow rate agrees well with the experimental data. Moreover, the variation and oscillation of the pressure around the rotating vane are confirmed. The difference of pressure appears in the vane tip as a result of the flow characteristics. Furthermore, the back flow into the rotor was observed.