• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1621-1627
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• 2013

This paper compares power losses between voltage controlled before and after using power conversion device in AC feeding system. For this purpose we present voltage control procedures and criteria and model high speed line and train using PSCAD/EMTDC to compare power losses in various feeding condition. Power losses of the simulation result in power control before and after in single point feeding system was reduced maximum 0.37 MW(23.8 %) and average 0.23 MW(20.5 %) when one vehicle load operates maximum load condition. When three vehicles operate maximum load condition in one feeder section, power losses after voltage control was reduced 1.03 MW(49.5%) compared to before voltage control. And, power loss of parallel feeding system is reduced the average 0.08 MW(7.2 %) compared to the single feeding system. In conclusion, adaptive voltage control method using power conversion device can reduce power losses compared with existing method.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.17-22
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• 2013

Diesel generator of nuclear power plant has a role for supply of emergency electric power to protect reactor core system in event of loss of off-site power supply. Therefore diesel generator should be tested periodically to verify the function that can supply specified frequency and voltage at design power level within limited time. For this purpose, appropriate maintenances in case that abnormal conditions were found are required in allowed time. In this paper, results of development of engine condition diagnosis technology and study on power plant of its technology for diesel generator are described.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.263-269
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• 2012

Condition-based maintenance (CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance system as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon Hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.574-578
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• 2009

Recently solar power system is increasing and planing to add it and 169 up to 2008 year march. In this paper, we researched sites installed PV system and analyzed problems for improvement of electrical safety. Results of actual condition research on the sites have problems such as infiltration of moisture, aging of electrode, destruction of insulation and backsheet crack and so on. So we suggest maintenance guide of solar power system in a inspection statistical chart, For making a secure about a electrical safety, we should inspect solar power system by the KESCO guide and rule by periods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.574-581
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• 2012

Condition-based maintenance(CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance strategy as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• ETRI Journal
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• v.38 no.5
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• pp.962-971
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• 2016

A wireless power transfer (WPT) system is generally designed with the optimum source and load impedance in order to achieve the maximum power transfer efficiency (PTE) at a specific coupling coefficient. Empirically or intuitively, however, it is well known that a high PTE can be attained by adjusting either the source or load impedance. In this paper, we estimate the maximum achievable PTE of WPT systems with the given load impedance, and propose the condition of source impedance for the maximum PTE. This condition can be reciprocally applied to the load impedance of a WPT system with the given source impedance. First, we review the transducer power gain of a two-port network as the PTE of the WPT system. Next, we derive two candidate conditions, the critical coupling and the optimum conditions, from the transducer power gain. Finally, we compare the two conditions carefully, and the results therefore indicate that the optimum condition is more suitable for a highly efficient WPT system with a given load impedance.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.111-114
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• 2000

Harmonics and fundamental reactive power of nonlinear loads in serious unbalanced power condition are compensated by current synchronous detection(CSD) theory which is also acceptable for single phase power system, but the CSD theory is not suitable any more in case of controlled independently harmonics and reactive component. Therefore a new algorithm the extended current synchronous detection (ECSD)theory for a three phase active power filter based on decomposition of fundamental reactive distorted components is proposed in this paper. The proposed ECSD theory is simulated and tested comparison with a few power theories under asymmtrical condition in power system.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.12
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• pp.1031-1035
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• 2002

The development of the solar and the wind power energy is necessary since the future alternative energies should have no pollution and no limitation. currently power generation system of MW scale has been developed, but it still has a few faults that its operation depends on with the weather condition. In order to solve these existing problems. combined generation system of photovoltaic(400W) and wind power generation system(400W) was suggested. It combines wind power and solar energy to have the supporting effect from each other. However. since the combined generation system cannot always generate stable output with ever-changing weather condition, power compensation device that uses elastic energy of spiral spring was added. In an experiment. when output of system gets lower than 12V(charging voltage), additional power was from the stored rotational energy of spiral spring.

• Journal of Power Electronics
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• v.2 no.1
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• pp.11-18
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• 2002

The development of the solar and the wind energy is necessary since the future alternative energies that have no pollution and no limitation are restricted. Currently MW Class power generation system has been developed, but it still has a few faults with the weather condition. In order to solve these existing problems, combined generation system of photovoltaic and wind power was suggested. It combines wind power energy and solar energy to have the supporting effect from each other. However, since even combined generation system cannot always generate stable output with everchanging weather condition, power storage apparatus that uses elastic energy of spiral spring to combined generation system was also added for the present study.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.250-255
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• 2018

This paper presents a method for minimizing standby power consumption in wireless power transfer (WPT) system via magnetic resonance coupling (MRC) that operates at 6.78 MHz. The proposed circuit controls the required capacitance according to operational condition in order to reduce standby power consumption. Based on an impedance characteristic of the class-E power amplifier, operational principles of the proposed circuit are analyzed. Moreover, to verify the effectiveness of the proposed class-E power amplifier, an 8 W prototype for WPT system is implemented. The measured input power of the proposed class-E power amplifier at standby condition is reduced from 5.81 W to 3.53 W.