• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.895-906
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• 2013

In this paper, we study the stabilization problem of switched systems with both controllable and uncontrollable subsystems. By using an average dwell time approach, we first establish a sufficient condition such that the switched system is exponentially stabilizable under appropriate switching signals. We also extend this result to the switched system with nonlinear impulse effects and disturbances. Numerical examples are given to illustrate the theoretical results.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.9-11
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• 2003

In power system planing and operation, voltage and reactive power control are very important. The voltage deviation and system losses can be reduced through control of reactive power sources. In general, there are several different reactive power sources, we used UPFC and switched shunt capacitor to improve the voltage profile and to reduce system losses in this study. Since there are many switched shunt capacitors in power system, so it is necessary to coordinate these switched shunt capacitors. In this study, Genetic Algorithm(GA) is used to find optimal coordination of UPFC and switched shunt capacitors in a local area of power system. In case study, the effectiveness of the proposed method is demonstrated in KEPCO's power system. The simulation is performed by PSS/E.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.138-143
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• 2011

Electric locomotive is adapted to high speed driving and mass transportation due to obtaining high traction force. The electric locomotive is operated by motor blocks and traction motors. Train speed is controlled by suppling power from motor blocks to traction motors according to reference speed. Speed control of the electric locomotive is efficient by spending energy between motor blocks and traction motors. Currently, switched reluctance motors have been studied because the efficient is higher than induction motors. In this paper, model of the switched reluctance motor is presented and the PID controller is applied to the model for the speed control by using Simulink. Asymmetry converter is used for real-time control and system performance is demonstrated by simulating the speed of switched reluctance motor including PID controller.

• Journal of the Korean Mathematical Society
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• v.48 no.4
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• pp.775-795
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• 2011

The disturbance attenuation problem for a class of discretetime switched linear systems with exponential uncertainties via switched state feedback and switched dynamic output feedback is investigated, respectively. By using Taylor series approximation and convex polytope technique, exponentially uncertain discrete-time switched linear system is transformed into an equivalent switched polytopic model with additive norm bounded uncertainty. For such equivalent switched model, one designs its switching strategy and associated state feedback controllers and dynamic output feedback controllers so that whole switched model is asymptotical stabilization with H-in nity disturbance attenuation base on switched Lyapunov function and LMI approach. Finally, two numerical examples are presented to illustrate our results.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.184-186
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• 2003

As STATCOM is considered to be installed in bulk power system, various studios are conducted to establish strategies for system operation considering STATCOM. This paper describes control strategy for coordinating STATCOM with existing switched shunt in bulk power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.673-678
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• 2013

This paper considers the stability of linear systems having an interval time-varying delay using a switched system approach. The time-delay system is converted to the switched system equivalently, and then a stability criterion in the form of linear matrix inequality(LMI) is derived by using a parameter dependent Lyapunov-Krosovskii function(PD-LKF). In constructing a PD-LKF, the decomposition is employed for delay free intervals, and the reduction of conservatism is shown analytically as the number of decomposition increases. Finally, two well-known numerical examples are given to show the reduction of conservatism compared to the recent results.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.295-297
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• 2002

In this study, Genetic Algorithm(GA) is applied for voltage and reactive power control in power system. In power system, switched shunt capacitors are used to improve the voltage profile and to reduce power losses. There are many switched shunt capacitors in power system. Therefore, it is necessary to coordinate these switched shunt capacitors. A Genetic Algorithm(GA) is used to find optimal coordination of switched shunt capacitors in power system. The effectiveness of the proposed approach is demonstrated in KEPCO's power system.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.833-836
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• 1993

A flyback type power converter circuit for switched reluctance motor drives is presented. In this converter circuit, the energy extracted from an off going phase is stored in an additional capacitor. The energy stored is used to either be returned to the source frequently or energize the conducting phase during the conduction interval through the transformer. The additional switch to pass the energy stored in the capacitor to the source or the conducting phase is switched under a relatively low voltage condition. Its switching frequency is relatively high so that the size of the transformer can be reduced. The design guideline for the capacitor and the transformer is described. The effectiveness of the presented converter circuit is compared to other circuits through the analysis and experiment.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.315-317
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• 1995

A simple drive circuit without position sensors for a switched reluctance motor is presented. The turn on and turn off points are determined by detecting the rate of change of the active phase current. The drive circuit consists of a current sensing resistor, RC filter, comparator, OP Amp, and OR gates. It is verified through the experiments that the switched reluctance motor with the proposed sensorless drive circuit is well operated in wide speed ranges.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1951-1953
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• 1997

A switched reluctance motor (SRM) has very simple structure and robustness. Generally, for driving SRM, several (6-8) switching devices are required. This is weakpoint for reducing the cost of SRM drive. In This paper, we simulate the single phase and three phase SRM, and we compare the performance or single phase SRM with that of three phase SRM through experiment. Finally we suggest the appropriate application of single phase SRM.