• International Journal of Control, Automation, and Systems
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• 제3권spc2호
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• pp.308-314
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• 2005

Transient stabilization with voltage regulation is investigated for a synchronous generator when the mechanical power is perturbed to any unknown value within its physical bounds so that the operating point of the system shifts to an unknown point. An adaptive excitation controller is designed based on the backstepping method with tuning functions. It will be shown that the adaptive control law proposed can achieve the convergence of the system states to the new equilibrium point in correspondence with the real value of the unknown mechanical power and the regulation of the terminal voltage to the required value. Simulation results are given to demonstrate the effectiveness of the proposed controller for the transient stabilization and voltage regulation.

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.494-501
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• 1999

In this research, ANN modeling method of SMES unit is developed for stability analysis, and the optimal site is selected to maximize stabilization effect of SMES unit. The ANN is trained by learning data which is obtained through the application of complex test function into the traditional mathematical mode. In order to verify the validity of proposed modeling method, fault data of sample power system is applied to both the traditional and the ANN models. When the response of traditional and proposed models are compared, the average error for the active and reactive power are 2.51[%], and 0.24[%], respectively. From the comparison, the relevance of proposed method is validated. For the transient stability analysis, an application method of the proposed model is presented, and the transient stability performance index, which describes system stabilization effect of SMES at disturbance, is also suggested, and optimal site selection method of SMES is presented. In the viewpoint of the voltage stability, system stabilization criterion of local bus is presented from P­V curve, and then optimal site which can maximize the voltage stabilization of the whole power system, is decided from the proposed voltage stability performance index.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.432-437
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• 1998

Power systems have uncertain dynamics due to a variety of effects such as lightning, severe storms and equipment failures. The variation of the effective reactance of a transmission line due to a fault is an example of uncertainty in power system dynamics. Hence, a robust controller to cope with these uncertainties is needed. Recently fuzzy controllers have become quite popular for robust control due to its capability of dealing with unstructured uncertainty. Thus in this paper we design an adaptive fuzzy controller using an input-output linearization approach for the transient stabilization and voltage regulation of a power system under a sudden fault. Simulation results show that satisfactory performance is achieved by the proposed controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1178-1179
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• 2008

This paper describes a modeling of fixed speed wind power generation system which comprise of wind turbine, generator and grid. The wind turbine is based on MOD-2, which is IEEE standard wind turbine, and includes a component using wind turbine characteristic equation. Fixed speed induction generator is directly connected to grid, so the variation of wind speed has effects on the electrical torque and electrical output power. Therefore the power control mode pitch control system is necessary for aerodynamic control of the blades. But the power control mode does not operate at the fault condition. So it is required some methods to control the rotor speed at transient state for stabilization of wind power system. In this paper, simulation model of a fixed speed wind power generation system based on the PSCAD/EMTDC is presented and implemented under the real weather conditions. Also, a new pitch control system is proposed to stabilize the wind power system at the fault condition. The validity of the stabilization method is demonstrated with the results produced through sets of simulation.

• 한국전산유체공학회지
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• 제6권1호
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• pp.47-55
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• 2001

The transient laminar reacting flows around fuel droplet have been numerically analyzed. The physical models used in this study can account for the variable thermophysical properties and the chemistry is represent by the one-step global reaction model. The present study is focused on the vaporization and ignition characteristics, flame structure including wake flame, transition flame and envelope flame, and interaction between droplets. Special emphasis is given to the triple flame structure and flame stabilization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1109-1111
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• 1997

The purpose of this paper is to analyze the effects of switching-over control for power system stabilization. Switching-over control is applied to western part of korea electric power system to improve transient stability and short-circuit capacity. It's effectiveness is demonstrated in terms of fault current level and critical clearing time which is quantitative evaluation means of transient stability. The effect of generator tripping for power system stabilization is also presented.

• Clinics in Shoulder and Elbow
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• 제26권3호
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• pp.302-305
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• 2023

The authors present a case of transient postoperative inferior subluxation of the shoulder after arthroscopic surgical stabilization for recurrent anterior dislocation. The patient was a 61-year-old woman with myasthenia gravis (MG). The first anterior shoulder dislocation occurred because of a fall to the ground. Despite a successful closed reduction, two more dislocations occurred in 3 weeks. Magnetic resonance imaging revealed an anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion, an engaging Hill-Sachs lesion, and large tears of the supraspinatus and infraspinatus tendons. The patient underwent arthroscopic rotator cuff repair and ALPSA repair with a remplissage procedure. Intraoperatively, no tendency for instability was found; however, a widened glenohumeral joint space and inferior subluxation of the humeral head without functional compromise was observed on the day after surgery and disappeared spontaneously on radiographs 2 weeks later. To the authors' knowledge, this is the first report documenting the occurrence of transient postoperative inferior subluxation of the shoulder in a patient with MG.

• 전기학회논문지
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• 제57권4호
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• pp.567-575
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• 2008

Transient security assessment(TSA) is becoming an essential requirement not only for security monitoring but also for stabilizing control of power systems under new electricity environments. It has already been pointed out that fast transient stability study is an important part for monitoring and controlling system security. In this paper, we discuss an energy function method for stabilizing control of transiently unstable systems by introducing generator tripping system to enhance the transient stability of power systems. The stabilization with less tripped power can be obtained by tripping the generators faster than out-of-synchronism relay. Fast transient stability assessment based on the state estimation and direct transient energy function method is an important part of the stabilizing scheme. It is possible to stabilize the transiently unstable system by tripping less generators before the action of out-of-synchronism relay, especially when a group of generator are going to be out-of-synchronism. Moreover, the amount of generator output needed for tripping can be decided by Transient Energy Function(TEF) method. The main contribution of this paper is on the stabilizing scheme which can be running in the Wide Area Control System.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 추계 학술대회논문집
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• pp.78-85
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• 2000

The transient laminar reacting flows around fuel droplet have been numerically analyzed. The physical models used in this study can account for the variable thermophysical properties and the chemistry is represent by the one-step global reaction model. The present study is focused on the vaporization and ignition characteristics, flame structure including wake flame, transition flame and envelope flame, and interaction between droplets. special emphasis is given to the triple flame structure and flame stabilization.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.242-246
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• 2001

The alternated forward multi resonant converter (AT forward MRC) is studied on the transient response and the measured loop gain for stability. The compensator is composed of the error amplifier with 3 poles and 2 zeros. This is optimized through the experiment with HP4194A network analyzer. We are initiated by the thinking of how to make the stabilization from the experimental results of loop gain curves. The loop gain, low frequency gain and gain margin are more improved through the experimental considerations. Also, the transient response is more enhanced effectively.