• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.611-616
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• 2018

In the cost based pool market in Korea, there is no compensation of reactive power because the fuel cost for reactive power is relatively low compared to that of active power. However, the change of energy paradigm in the future, such as widespread integration of distributed renewable energy source, will prevent the system operator from mandating the reactive power supply without any compensation. Thus, in this study, we propose the reference voltage of the 345 kV transmission system that minimizes the reactive power supply. This is closely related to the economic dispatch of reactive power aiming at minimizing the compensation cost for the reactive power service. In order to verify the effectiveness of the proposed reference voltage, the simulations are performed using the IEEE 14 bus system and the KEPCO real networks. The simulation results show that a voltage lower than the current reference value is recommended to reduce the reactive power supply and also suggest that the current voltage specification for the 345 kV system needs to be reviewed.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.159-160
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• 2016

본 논문에서는 최근 건설기계용으로 연구되고 있는 E-TCS의 Power Electronics System에 대한 Topology와 제어방법을 제안한다. 디젤엔진과 같이 사용되는 E-TCS는 압축기와 터빈 그리고 요구되는 회전속도로 고속회전 및 발전이 가능한 모터와 이를 제어하는 인버터로 구성된다. 기존의 E-TCS를 위한 Power Electronics System의 경우 배터리의 전압강압으로 인버터의 전류량이 증가하여 Power Electronics System 및 모터의 Volume이 커지는 단점이 있으며, 특허가 존재하여 사용이 어렵다. 본 논문에서는 이와 같은 단점을 개선한 E-TCS를 위한 새로운 Topology 구성 및 제어방식을 제안한다.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.567-569
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• 1997

A control system using a PLC has been developed for a single tower drier(STD) in a CANDU type nuclear power plant. This system will replace the existing STD control system which was implemented with mechanical timers and relays. The new control system makes it possible for an operator to perform more precise time and dew point control for the STD, thanks to the high efficiency and flexibility of the PLC. The operational cost for the control system is much reduced compared to the existing system.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.44-46
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• 2005

A SMES can be a perfect alternative energy storage device to the chemical batteries which are needed by most of the renewable energy supply systems. The chemical battery storage system is so expensive to maintain and causes another environmental problem because they are not recyclable. But, SMES has semi-permanent lifetime and no environmental problems cause it only need coolants which is non flammable, clean and recyclable gas. In order to verify the feasibility of a SMES for the renewable electrical power supply system, electrical characteristics of a test SMES coil with the photovoltaic power system were analyzed in this paper. Simulation results show that we can charge 40 amps of current in test SMES coil using solar power system. The experimental verification will be performed just after development of the peak power tracking system for the solar system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.3
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• pp.128-132
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• 2006

Interstate electric power system, as an alternative for energy cooperation under regional economic bloc, has been hotly debated before progressing the restructure in electric power industry and rapidly expanded in many regions after 1990s. Especially, since northeast asia has strong supplementation in resource, load shape, fuel mix etc., electric power system interconnection in this region may bring considerable economic benefits. Moreover, since Korean electric power system has a great difficulty in a geographical condition to interrupt electricity transaction with other countries, it has been expanded as an independent system to supply all demand domestically. As a result, Korean electric power system makes considerable payment for maintaining system security and reliability and expands costly facilities to supply a temporary summer peak demand. Under this inefficiency, if there are electricity transactions with Russia via the North Korea route then economic electric power system operation nay be achieved using seasonal and hourly differences in electricity price and/or load pattern among these countries. In this paper, we estimate price cap of transacted electricity via interstate electric power system in northeast asia. For this study, we perform quantitative economic analysis on various system interconnection scenarios.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.51-57
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• 2004

This paper describes the dynamic performance of a variable speed wind turbine system responding to a wide variety of wind variations. Modeling of the wind generation using power electronics interface is proposed for dynamic simulation analysis. Component models and equations are addressed and their incorporations into a transient analysis program, PSCAD/EMTDC are provided. A wind model of four components is described, which enables observing dynamic behaviors of the wind turbine resulting from wind variations. Controllable power inverter strategies are intended for capturing the maximum power under variable speed operation and maintaining reactive power generation at a pre-determined level for constant power factor control or voltage regulation control. The components and control schemes are modeled by user-defined functions. Simulation case studies provide variable speed wind generator dynamic performance for changes in wind speed

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.73-75
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• 2000

The new distribution automation system was developed in KEPCO just recently. This system has many functions for remote control and data acquisition but it has not all functions for the full automated distribution system. This paper presents the contents of many kinds of additional application programs on the stage of developing and coming to the final completion for the large scaled distribution automation system.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.63-65
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• 2007

Recently with increase consumption of electric power, the scale of the electric system becomes bigger and complex. Then, it is increasing the hardship in the operation of electric system and the continuance of stability. Especially, as the differences between demand and supply in electric power keeping low frequency oscillating attenuation from electric power have been very important in the continuance part of stability. The more control time of electricity system is getting faster with digitalization the more stability of electricity system is getting worse. As solutions of these problems, by establishing Power System Stabilizing Controller putting PSS output signal and putting damping to vibration of the rotor at generators's AVR in area where is oscillated, We are willing to contribute the electricity system by holding in generator output vibration.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1056-1057
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• 2015

A common DC bus is a useful connection for several DC output sources such as photovoltaic (PV), fuel cells, and batteries. Operation of the common DC power system with more than two DC output sources, especially in a stand-alone mode, requires a control scheme for the stable operation of the system. In this paper, a control scheme has been developed for applying DC power sources to the distribution system. The purpose of the control scheme is to make the best use of the DC power sources. The DC power system consists of PV, two energy storage systems and a DC-AC inverter with the control scheme. A distribution system was modeled in PSCAD/EMTDC. As the results, the control scheme is applied to the DC-AC inverter and the DC-DC converter for transfer operations between the grid-connected and the stand-alone mode to keep the DC bus and the AC voltage constant. The results from the simulation demonstrate the stable operation of a grid connected DC power system.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2024-2026
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• 1998

Many power plants built 20-30 years ago are facing problems associated with the excitation system used for controlling generator output voltage. After years of reliable operation, generation is experiencing increased down time due to maintenance associated with the exciting excitation equipment. Reliability of the excitation system has become an issue, especially where many of these generation plants may be critical to the internal processes used for manufacturing. Wear out mechanisms such as those associated with the wire wound rheostat the electromechanical voltage regulator, insulation failures of the rotating exciter and commutator deterioration have become real problems typical of many older installations. These are some of the issues that are affecting system reliability for older power plants. This paper will address typical problems associated with the old excitation systems and the justification for a replacement static excitation system used in many Paper Mills.