• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.583-584
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• 2015

Energy Storage System(ESS) can be used as several purposes such as uninterruptible power supply (UPS), frequency regulation, maximum load cut, and etc. This paper analyzes and simulates the reclosing operation in distribution system with ESS for frequency regulation and maximum load cut. To solve the effect from ESS, two sequences in reclosing process are added to conventional reclosing. The modelings and simulations of reclosing operation using EMTP/ATPDraw are performed.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.353-358
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• 2012

In this paper, three-phase power equalizing system (PES) with UPS function is proposed. This system is based on NiMH battery with battery management system. The power conversion circuit is composed with the three-phase converter/inverter, the bi-directional converter, and the thyristor switches. The three-phase converter/inverter provides the power to the grid or get the power from the grid. Also, it operates as a UPS. The bi-directional converter charges or discharges the battery. The thyristor switches are used for connecting/disconnecting with the grid and the load. A 15 kW prototype is implemented for the verifying the performance of the proposed system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.10
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• pp.102-110
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• 2012

This paper propose the advanced topology of UPQC, its DC link is connected with Lithium battery, to compensate the momentary interruptions. The proposed system can be operated as UPS mode using the parallel inverter, which control the charge or discharge of battery, in case of the interruption. We dvelop 100kVA UPQC using the proposed topology to rise the power quality and the reliability of Microgrid. We verify its usefulness through voltage compensation test, UPS operation test and etc. using Microgrid test facility.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2085-2087
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• 1997

The UPS for power plant is mainly used as the critical power supply of power plant. This is very much alike to the general UPS but it requires the special design criteria of power plant. In this study, we designed and develope system according to the design criteria of p plant. In the development of the special system, the designs of IGBT Drive, heat protection and monitoring system, and p components are key techniques. This Paper describes the power circuits, key techniques, the control and monitoring of the developed UPS(DC 125V $3{\Phi}$ 100K Finally, using the UPS we verified superiority through the type test.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2082-2084
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• 1997

This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode, it is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. And the current regulated instantaneous voltage control scheme is used in back-up power mode. The system model and control algorithm are described and analyzed, and the system Performance is verified by the simulation and experimental results.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.53-59
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• 1999

In this paper, a bi-directional UPS with the performance of active power filter has been proposed. The operation of the proposed system can be divided into two modes, such as the active power filter mode and the battery back-up power mode. To improve the transient response for the effective compensation of harmonics and reactive power in active power filter mode, a novel closed-loop control strategy is used to calculate the reference current instantaneously. Finally, the performance of proposed UPS is verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1049-1051
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• 2001

This paper proposes a new control strategy of multifunctional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode, it is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. And the current regulated instantaneous voltage control scheme is used in back-up power mode. The system model and control algorithm are described and analyzed, and the system performance is verified by the simulation results.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.19-20
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• 2016

This study deals with the control method of the output impedance for the UPS(Uninterruptible Power Supply) system's wireless parallel opertaion. In order to avoid using any communication between modules, the P/Q droop method was applied. The experiment result based on NPC(Neutral Point Clamped) inverters is included.

• Journal of Power Electronics
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• v.16 no.2
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• pp.621-630
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• 2016

In this paper, a single current sensor technique (SCST) is proposed for single-phase full-bridge inverters. The proposed SCST measures the currents of multiple branches at the same time, and reconstructs the average inductor, capacitor, and load current in a single switching cycle. Since all of the branches' current in the LC filter and the load are obtained using the SCST, both the inductor and the capacitor current feedback schemes can be selectively applied while taking advantages of each other. This paper also analyzes both of the current feedback schemes from the view point of the closed-loop output impedance. The proposed SCST and the analysis in this paper are verified through experiments on a 3kVA single-phase uninterruptible power supply (UPS).

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.443-444
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• 2014

Using the ESS(Energy Storage System) as a UPS(Uninterruptible Power Supply) is being studied recently. When the system is operating at UPS mode in integrated ESS and UPS system, the grid supplying power is disconnected and power from PV generation and battery are supplying to load. Operating in UPS mode, when PV generation power is diminished by partial or total clouded situation, DC-link voltage fluctuates. The fluctuation of DC-link voltage influences the load and system as sensitive loads may malfunction. This paper suggests the DC-link ripple voltage compensation algorithm in bi-directional converter. The algorithm stabilize the DC-link and load voltage.