• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.13-19
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• 2001

This paper deals with decentralized control scheme and its application to multi-machine power systems. Decentralized control scheme has several practical advantages, because power system has geographically distributed characteristics. In this paper, decentralized observer-based optimal Power System Stabilizer(PSS) and Thyristor-Controlled Series Capacitor(TCST) controller are designed and tested in WSCC 9 bus system with one TCSC installed. Simulation results show that the proposed decentralized controller has satisfactory performances comparable to the centralized controller. In addition, using modal analysis, this paper shows that the proposed decentralized controller significantly affects only one pair of eigenvalues which have high participation with each generator, while slightly affects other eigenvalues. This result indicates that the application of the decentralized control scheme to enhance power system dynamic stability via excitation control have potential advantages because each low-damped mode occurs dominantly by each decentralized subsystem.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.31-44
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• 2024

People have been using more energy in the last years. Several research studies were conducted to develop sustainable energy sources that can produce clean energy to fulfill our energy requirements. Using renewable energy sources helps to decrease the harm to the environment caused by conventional power plants. Choosing the right location and capacity for DG-RESs can greatly impact the performance of Radial Distribution Systems. It is beneficial to have a good and stable electrical power supply with low energy waste and high effectiveness because it improves the performance and reliability of the system. This research investigates the ideal location and size for solar and wind power systems, which are popular methods for producing clean electricity. A new artificial intelligent algorithm called Nutcracker Optimization Algorithm (NOA) is used to find the best solution in two common electrical systems named IEEE 33 and 69 bus systems to examine the improvement in the efficiency & reliability of power system network by reducing power losses, making voltage deviation smaller, and improving voltage stability. Finally, the NOA method is compared with another method called PSO and developed Hybrid Algorithm (NOA+PSO) to validate the proposed algorithm effectiveness and enhancement of both efficiency and reliability aspects.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.371-380
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• 2003

In this paper, a new design method of H$H_\infty$-Qn PSS using genetic algorithm(GA) is proposed to efficiently damp low frequency oscillations despite the uncertainties and various disturbances of power systems. The selection method of evaluation function is proposed for selecting the robust PSS parameters. All QFT boundaries are satisfied automatically and H$H_\infty$-norm is minimized simultaneously without trial and error procedure. The eigenvalues and the damping ratio of dominant oscillation mode are investigated to evaluate performance of designed controller for one machine infinite bus system. A disturbance attenuation performance is investigated through singular value bode diagram of the system. Dynamic characteristics are considered to verify robustness of the proposed PSS by means of nonlinear simulations under various disturbances for various operating conditions. The results show that the proposed PSS is more robust than conventional PSS.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.887-890
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• 2004

This paper presents a microprocessor controlled electronic ballast for HID lamps, which gives automatic switching between MH and HPS lamps. Lamp identification is carried out by checking variation of lamp impedance at warm-up phase. Direct spread spectrum is done by applying 1 kHz triangular wave for removing acoustic resonance. This frequency modulation of 1 kHz gives also low EMI level. The microprocessor controls the voltage of DC-bus, the voltage of ignition pulses, the power of output. A 250W electronic ballast is implemented with ATmega16 CPU.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.255-258
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• 2000

The supplementalγ controls of the FACTS are designed for the enhancement of the small signal stability in power system. The designed supplementary controllers using residue are applied to SVC or TCSC for the improving the damping ratio of dominant eigen value in the New England and 39 bus test system as the sample system. The results show the validation of the supplementary controller for the enhancement of the eigenvalues which have the low frequency oscillations with poor damping ratio as the unstable problem in the sample system.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2057-2059
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• 1998

In order to maintain a high quality output voltage, conventional UPS systems use complex filters with large passive components. To overcome this drawback, real time feedback control schemes have been invested. However, these techniques require a high inverter switching frequency to dynamically adapt to changing load conditions reduce harmonics of the output voltage, thereby rendering the system inadequate for high power applications. This paper presents real time digital signal processor(DSP) control of a large capacity UPS system feeding nonlinear loads to provide a sinusoidal inverter output voltage, unity input power factor, low bus voltage ripple, and excellent transient response.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1228-1230
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• 1998

The deadbeat control has many advantage such as the ouput response without a ripple and the fast settling time. This paper presents a deadbeat control system to damp out the sustained low frequency oscillation. The proposed deadbeat control system consists of th integral controller and the state observer, and it is simulated on the one-machine infinite-bus model of a power system. The efficiency of the proposed control system is verified through the several case studies.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.31-35
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• 2003

This paper presents a microprocessor controlled digital ballast for HID lamps, which gives intelligent features such as a precise power control, optimum ignition voltage and detection of end of life. Average current mode PFC is employed for reducing EMI and a universal input. Direct spread spectrum is done by applying 1 KHz triangular wave for removing acoustic resonance. This frequency modulation of 1 KHz gives also low EMI level and no ripple on lamp current. The microprocessor controls the voltage of DC-bus, the voltage of ignition pulses, the power of output and the bandwidth of spread spectrum. A 250W digital ballast is implemented with an efficiency of 93％ and a maximum EMI level of 55 ㏈${\mu}$V.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.5
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• pp.81-92
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• 2013

The satellite includes many release mechanisms such as solar array deployment, antenna deployment, cover to protect contamination in scientific equipment, pyro value of the propulsion subsytem, and bypass device in Li-Ion cell module. A drive the initiators is a critical to the successful mission because the initiators of release mechanism driving by the pyrotechnic circuit is operated in single short. The pyrotechnic circuit has to provide switching network for safety. A typical switching network has defect consisting of high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit is required some form of power conditioning to reduce the peak power demanded from the bus if the initiators are to be fired from the main bus. This paper design a pyrotechnic circuit synchronized to the fire-command to activate the fire switch to overcome use high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit provides a current limited widow pulse for fire current synchronized to the fire-command to insure that fire switch will only carry the current but never switch it. The current limited widow pulse for fire current can be possible to use low current rating and light mass switch in switching network. The current limit function in the pyrotechnic circuit reduces supply voltage to initiator and provides the effect of power conditioning function to reduce peak bus power. The pyrotechnic circuit to apply satellite development on geostationary orbit is verified the function by test in development model.