• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1948_1949
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• 2009

All the power generating station require dc auxiliary power systems to operate those dc components that must be available if a loss of ac power occur. Some examples of such components are auxiliary motors, circuit breakers, relays and solenoids. The dc source may be one common battery for both power and control or two separate batteries; one for power and another for control. Typically, a dc auxiliary power system is designed as an ungrounded system, instead of grounded system, so that a low-resistance ground fault on one of its two polarities will not affect the operation of the system, thus increasing system reliability and continuity of service. A ground detector should provide a high polarity-to-ground resistance so that a single ground fault occurring on the system will not affect the operation of that system. Sensitive relays have been known to energize momentarily while the cable and capacitive charge to ground shifts[1]. A power station had experienced this kind of incident and performed root cause analysis based on PC based simulation program known as PSpice. This simulation showed adapted relays on the system energize momentarily and design criteria on this relay should be corrected.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.245-249
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• 2009

Antarctic King Sejong Station was established in King George Island, the South Pole in 1988, and has been executing the monitoring studies on the change of antarctic natural environment. As an available power, the wind energy generator has been used in the form of hybrid with mainly diesel generator. Because the wind generation power sharply changes by wind energy, it must be careful during the system operation. When the power system becomes stable, the output performance of wind energy generator becomes stable. But, in case of unstable system, the errors frequently occur on the wind energy generator and it badly impacts the power system by output of wind energy generator. The purpose of this paper is to analyze suitability while operating the system of 10kW wind energy generator at Antarctic King Sejong Station, an isolated area, and to analyze the problem and improvements by power quality.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.99-106
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• 1987

Comparison study on the radiological effects by radionuclides from hypothetical 1,000MWe coal-fired power station and nuclear power plant is made. This paper describes the radiological effects only for gaseous effluents released in normal operation. Source terms for coal-fired Power station are quoted from foreign data and those for nuclear power plant are calculated for reference power plant. Gaussian plume model is used to assess atmospheric dispersion of radioactive effluents based on one year meteorological data of Kori site and individual doses are calculated at the maximum X/Q point. Doses from nuclear power plant are slightly more than those from coal-fred power plant. In the case of coal-fired power plant, doses by ingestion of contaminated vegetation are 73.5% of total doses.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.425-430
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• 2022

A pumped storage power station is an important means to solve the problem of peak load regulation and ensures the safety of power grid operation. The doubly fed variable-speed pumped storage (DFVSPS) system adopts a doubly fed induction machine (DFIM) to replace the synchronous machine used in traditional pumped storage. The stator of DFIM is connected to the power grid, and the three-phase excitation windings are symmetrically distributed on the rotor. Excitation current is supplied by the converter. The active and reactive power of the unit can be quickly adjusted by adjusting the amplitude, frequency, and phase of the rotor-side voltage or current through the converter. Compared with a conventional pumped storage hydropower station (C-PSH), DFVSPS power stations have various operating modes and frequent start-up and shutdown. This study introduces the structure and principle of the DFVSPS unit. Mathematical models of the unit, including a model of DFIM, a model of the pump-turbine, and a model of the converter and its control, are established. Fast power control strategies are proposed for the unit model. A 300 MW model of the DFVSPS unit is established in MATLAB/Simulink, and the response characteristics in generating mode are examined.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.73-75
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• 2002

This paper presents the properly method of system security and facility countermeasures. We performed simulation for yearly peak of Korean power system in 2002 under the reactive power problem in a nuclear power plants. Analysis of the problems in power system operation by power flow, fault and stability study. Establishment of power system optimal operating plan by stabilizer and maintaining the reasonable voltage level.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.9-16
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• 2007

Currently, the measurement of RF parameters for a base station in operation is typically limited to easily measured forward path items. In this paper, the forward monitoring ports of base stations are used to measure the reverse RF performance. The system has been implemented and effectiveness has been proven on an operating base station. The receiver sensitivity is measured using an internal CDMA modem which is used to monitor the output power based on closed loop power control when the modem is connected to the base station via a voice call. In order to improve accuracy, in addition to the modem Tx adjust(TxAdj) parameter, the detector's actual measurement is used. For accurate receiver sensitivity, the measurement should be made when there is no traffic which is not possible on an operating base station. Therefore, pilot channel chip energy to received signal power spectral density ratio$(E_c/I_o)$ compensation method is used to offset the receiver sensitivity degradation with voice traffic increase.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.82-86
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• 2010

In this paper, a power amplifier module for WCDMA base-station applications is designed and implemented using GaN field-effect transistors (FETs), which uses an envelope tracking bias system. The designed module consists of an high gain MMIC amplifier, a driver amplifier, a power amplifier, and bias circuits for envelope tracking applications. Especially, a FET bias sequencing circuit and two isolators are integrated for stable RF operations. All circuits are assembled within a single housing, so its dimension is just $17.8{\times}9.8{\times}2.0\;cm3$. Measured results show that the developed power amplifier module has good envelope tracking capability: the power-added efficiency of 35% at the output power range from 30dBm to 40dBm over a wide range of drain bias.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.18-22
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• 2008

A few intake stations have vibration problems caused by pipes. The vibration transffered from pipes excites building severely. Therefore, the crack is generated on building wall and people who work at intake station are damaged. In this paper, the vibration is measured and analysis is carried out for pipes at intake station in order to identify the usefulness and effectiveness of the solution proposed for pipe resonance avoidance. According to the result of analysis, the vibration of pipes is reduced by bellows.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1327-1330
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• 2004

An underwater robotic system has been developed and applied to visual inspection of reactor vessel internals. The Korea Electric Power Robot for Visual Test (KeproVt) consists of an underwater robot, a vision processor-based measuring unit, a master control station and a servo control station. The robot guided by the control station with the measuring unit can be controlled to have any motion at any position in the reactor vessel with $\pm$1 cm positioning and $\pm$2 degrees heading accuracies with enough precision to inspect reactor internals. A simple and fast installation process is emphasized in the developed system. The developed robotic system was successfully deployed at the Younggwang Nuclear Unit 1 for the visual inspection of reactor internals.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.775-778
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• 1992

In 1980, 154kV OF cable was installed at the Cheong-Pyeong pumped-storage power station. Effective head of this pumped-storage station is 250m between upper and lower re-servior and length of cable route is 750m. However, several failures have happened owing to steep slope during the operation. 154 kV XLPE cable was applied for this power station to eliminate a lack of stability on account of steep slope and successfully installed in 1991. Meanwhile, installation procedure brings about many problem to be solved. In this paper, we describe the counter measure of cable sliding phenomena caused by heat shrinkage as well as the method of installation of cable under the steep slope condition. And hereafter, we think this paper will be a good reference to design and installation of 154kV XLPE cables in steep slope turnnel at urban areas.