• KIPE Magazine
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• v.4 no.1
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• pp.19-27
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• 1999

• 전기의세계
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• v.52 no.7
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• pp.28-34
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• 2003

• 전기의세계
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• v.52 no.7
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• pp.35-41
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• 2003

• 전기의세계
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• v.52 no.7
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• pp.52-55
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• 2003

• 전기의세계
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• v.52 no.7
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• pp.64-69
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• 2003

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.1-8
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• 2010

The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.354-361
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• 2014

The Unified Power Flow Controller (UPFC) can flexibly manage power flow and maintain line voltage. The UPFC consists of two inverters in parallel side and series side. In parallel side, the reactive power can be compensated to improve the power factor. In series side, the voltage drop can be compensated to maintain proper line voltage. It is necessary for the operation in both sides to output the current and the voltage quickly and accurately. As the method for the UPFC control, the deadbeat control with state observer is applied. The deadbeat control is able to realize a quick response of the current and voltage control for only a sampling period compared with the general PI control. A principle and simulation results are presented in this paper.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_1
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• pp.559-567
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• 2020

As the renewable energy market grows, grid-connected inverters have been improving and expanding in several fields in recent years because energy conversion devices are the main components of solar systems. In this paper, a high-precision new grid-connected three-phase inverter system is proposed. The proposed system consists of a main inverter, a sub inverter and a transformer. The main inverter operates at a low switching frequency and high power and transmits power to the grid. A sub-inverter connected in series with the transmission line through a matching transformer operates at lower power than the main inverter to provide input values to the transformer. The transformer acts as a power supply according to the voltage compensation value. This study is based on the principle of operation of the UPFC(Unified Power Flow Controller) structure used to regulate power flow in AC transmission lines. The grid-connected inverter system proposed in this paper is implemented with high precision and high resolution. The proposed system was verified through its ability to enhance and ensure the safety of the proposed system through simulation and experiment.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.374-376
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• 2001

FACTS technology is developed into the sophisticated system technology which combines conventional power system technology with power electronics, micro-process control, and information technology. Its objectives are achieving enhancement of the power system flexibility and maximum utilization of the power transfer capability through improvements of the system reliability, controllability, and efficiency[1]. As a series and shunt compensator, UPFC consists of two inverters with common dc link capacitor bank. It controls the magnitude of shunt bus voltage and real and reactive power flow of transmission line[2]. In this paper, we present the design and control algorithm of UPFC simulator for KERI simulator. As a control algorithm is implemented by digital controller, we consider sample-and-hold of signals In this simulation, we use EMTDC/PSCAD V3.0 software which can simulate instantaneous voltage and current.

• 전기의세계
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• v.52 no.7
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• pp.42-45
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• 2003