• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1187-1189
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• 2000

This paper presents a high power-hybrid multilevel PWM rectifier with unity power factor. The features and advantages of the proposed PWM rectifier can be summarized as follows; 1) It realizes the high power high voltage AC/DC power conversion. 2) It uses no transformer which is bulky and heavy, 3) It has hybrid structure so that switching devices can be effectively utilized, 4) It produces high quality AC current even in high power high voltage applications, 5) The input power factor remains unity by simple modulation index control. The multilevel rectifier is analyzed by using the circuit DQ transformation whereby the characteristics and control equations are obtained.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.505-508
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• 2006

Recently, concern for tidal power is being increased by newly recycled energy. It is important to decide on the maximum power estimate operation and it's stop by applying the difference of water level between tide level and artificial reservoir for the administration of tidal development. For maximum output of power through turbine generator, administrative variables and process on efficiency of hydraulic turbine and inflow discharge of reservoir is quite complicated because it is run through the connection of discharge-gate and turbine On the development of this model, the administrative process is decided, Operation block is presented for it's maximum power estimate.

• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.36-40
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• 2019

In this study, we compared the operational rates of natural gas, coal, nuclear power and renewable energy based on the data of power generation and power generation facilities produced in summer season(from June to August) during the last four years(2015~2018). Nuclear power and coal power, which are responsible for basic power generation, were guaranteed to be economical as the actual generation capacity remained 60% higher than the cost of power generation. On the other hand, natural gas generation and new renewable energy generation have a very low actual operation rate of 29.5% and 27.3% compared to investments in power generation facilities, making it difficult to lower the cost of power generation. However, coal generation has structural problems in terms of greenhouse gas, fine dust. On the other hand, natural gas generation is relatively low and even though it is safe, it is difficult to secure economic feasibility as it is bound by a peak power system. Therefore, it is only possible to achieve balanced development of energy sources when there is a change in the development policy.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.161-167
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• 2013

The purpose of this study was to assess power loss in the computer and office automation equipment and identified a way to save power consumptions through field measurement. In this study, the meaning of standby power was to consume power while waiting for the use of any electronic equipment. This standby consumption was about 11% of total power consumption even though we did not seriously realize it. Therefore, it was very important to measure accurate power consumption at the standby status of electronic equipment. In addition, it also helped to reduce potential risks of electricity associated disasters. This study proposed the way to reduce power losses through automatic turn off switches for power outlets and switches. Finally, this study can evaluate power consumption patterns that can reduce power consumptions and potential risks of power related disasters. This also can achieve the goals of sustainability that can reduce environmental impacts by lowering energy consumptions and greenhouse gas emissions.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.85-89
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• 1998

A switching power stage is a very nonlinear system because it has two or more operation modes in one switching cycle. To model a switching power stage, the state space averaging method has been developed. Though it allows a unified treatment of a large variety of switching power stages, the model it yields is always very nonlinear. So, it is required to linearize the averaged model. But it is well known that a controller for a nonlinear plant designed by the linearization frequently fails in showing satisfactory control performance. Hence it is very natural to try to design a nonlinear controller for a switching power stage. In design of a switching power system, nonlinear control approaches such as adaptive control and fuzzy control have been widely studied so far. In this research, a recently developed control method, time delay control is briefly studied and a design example for a ZVS PWM half bridge converter is given. The performance of the time delay controller is compared to its conventional counterpart, PI controller by computer simulations.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3092-3098
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• 2011

This paper deals with analysis of measuring power dissipation when Maglev is running. With the various running scenarios for Maglev, power dissipation was measured and a comparative analysis of it and wheel-on rails were carried out. The purpose of this paper is to confirm the efficiency and economics on operation of Maglev and reflect detail design later. When the running scenarios of Maglev are the status of landing on and levitation, running at rated acceleration and deceleration and according to changes of velocity, the power dissipation was measured. The measured results are analyzed considering with apparent electric power and active power, reactive power and power factor etc. Due to the limited test track condition, it is very limited to compare and analyze Maglev and general trains. Nevertheless, It is a task of great significance to identify the efficiency and economics on operating Maglev through the results of measuring power dissipation. In the future, measuring power dissipation through more various scenarios will be carried out, and the results will be reflected the design.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1997-2004
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• 2011

The $2{\times}25kv$ AT electric power feeding method in the A.C. electric train adopts the one-phase power feeding method as the standard due to a voltage phase difference, and the distance between the two neighboring substations is 50km due to voltage drop. The one-phase power feeding method makes the system operation feasible, while making it unfavorable for power supply. Moreover, railroad involves large-capacity single-phase load, and if it is expected to continue to rise, it is necessary to research on measures to stabilize the supply of power to railroad cars with the existing facilities. In this study, a parallel power feeding method between neighboring substations is proposed to stabilize the supply of electric power to electric railroad cars under the 2*25kv AT power feeding method and the loop current induced by voltage phase difference between the two neighboring substations during parallel power feeding is investigated.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.425-433
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• 2012

As the demand for electric power increases rapidly and the amount of fossil fuels decreases year by year, making use of renewable resources seem very necessary. However, due to the discontinuous nature of renewable resources and the hierarchical topology of existing grids, power quality and grid stability will deteriorate as more and more distributed generations (DGs) are connected to the grids. It is a good idea to combine local utilization, local consumption, energy storage and DGs to form a grid-friendly micro grid, these micro grids can then assembled into an intelligent power system - the smart Grid. It can optimize power flow and integrate power generation and consumption effectively. Most importantly, the power quality and grid stability can be improved greatly. This paper depicts how the smart grid addresses the current issues of a power system. It also figures out the key technologies and expectations of the smart grid.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1901-1902
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• 2006

In recent years, it has been a worldwide trend that many power utilities gave their attention to develop and operate their power plants, substation and distribution systems. Following this trend, KEPCO(Korea Electric Power Corporation) has developed many electric automation systems with various communication networks. It has been natural that the automation systems are just focused on to remote devices when they come to be designed. But, we have to shift the focus to the automation system itself. We have developed the Multi-service Optical Transmission System (M-OTS) for electrical power systems. It can be adopt to not only distribution power field but also the transmission power field. The result strongly shows that the system is potentially beneficial in reliability, speed, and expandability. This paper presents some of initial design efforts and results toward a KEPCO's communication system in distribution areas.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.603-605
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• 2006

To reduce inference of any power delivery failures in underground power cable, power system operators are trying to find effective way of finding fault location as soon as possible. But it is very difficult to find fault location exactly for underground power cable. We are developing fault location system for underground power cable which can detect its fault location exactly. This new system monitors current and voltage of underground power cable by using low voltage and current sensors and if there are any accidents, it records its transient signal. Fault location is calculated by analyzing recorded signal. To develop fault location system for power cable, we needed fault simulation system and we installed it physically and tested. In this rapers, we describe on describe of fault location system for underground power cable.