• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.60-63
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• 2001

Investigating electromagnetic emissions of inverter power sources for resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and intermittent operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, snubber circuits and constructional aspects exert a great influence on the conducted emission of resistance welding inverters.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.503-510
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• 2020

The importance of DC breakers as key protection equipment is increasing in accordance with growing concerns on MVDC distribution network systems without DC/AC conversion. Different from the situation in AC systems, no natural zero-crossing point exists in DC systems. Thus, DC breaker technology is more difficult than AC breaker technology. The solutions for DC breakers can be divided into three types: mechanical, power electronics, and hybrid. In this study, the operating principles of several topologies of hybrid circuit breakers and that of the proposed DC breaker are analyzed and simulated by sorting two types. The breakers are compared in terms of the type and number of semiconductors, volume, power loss, auxiliary components, isolation, and other aspects. The advantages and disadvantages of the breakers are also analyzed.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2540-2542
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• 2002

In recent years, it is a worldwide trend that many power utilities focus their attention to employ up-to-date communication technology to the automation of their power plants and distribution systems. Automation Systems in Korea was installed using twisted pair cable(TPC), power line carrier(PLC), coaxial cable(CA), wireless network(wireless data, TRS and PCS). Among the communication media only Satellite Communication guarantees the reliable communication in case of emergency such as a flood, a heavy snow and an earthquake. It can integrate two-way satellite systems to existent nationwide SCADA controlling points of electric power transmission & distribution system that enables real time remote monitoring and controlling automatically. This paper presents some of design efforts for the satellite communication network as the media of Automation Systems.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.27-27
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• 2008

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2189-2191
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• 2000

Electric power systems are becoming advanced by using new technology year by year However, in electric power system environments. electromagnetic interference occurs in measurement, supervisory and control systems, especially in sensors. Optical sensor technologies are useful for solving the problem, since they are not affected by electromagnetic interference because they are composed of insulting materials. In this paper, some applications of optical sensor technology to electric power systems are introduced.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2414-2416
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• 2004

Power Companies worldwide are undergoing tremendous change in the Automation issues. It becomes a worldwide trend that the power utilities focus their attention to the automation of their power plants and substation systems, employing recent advanced communication protocols. In this paper, we discuss the standard communication protocols which can be applied in the automation systems to help utilities reduce their operation and maintenance costs while at the same time meeting new requirements for communications to RTUs and intelligent electronic devices(IEDs). Especially, we introduce EC 61850 protocol which is developing for international standard by IEC.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.667-675
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• 2009

Faults can be generated at electric power systems by variety of both certain and uncertain reasons, which may cause harmful effects on electrical apparatuses under operation and stability of electric power system operations, and may also lead to great confusions and inconveniences to individual livings, public works, industrial activities, services, military affairs, etc.. In some cases, intentional inductions of faults are committed for specific purposes, and it is necessary to understand the procedures of fault by some foreign materials. In this paper, compositions and operations of electric power systems, summaries of electrical fault phenomena and fault protection, and restrictions to power system operation were outlined. And the analogies on the procedure of faults from former papers were introduced, and test results that revealed the validity of those analogies were also introduced.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.121-125
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• 2016

KEPCO has completed the installation and demonstration of a 52 MW battery energy storage system (BESS) for frequency regulation. Especially, 24 MW BESS is for Automatic Generation Control (AGC) in Shin-Yongin substation. Recently, KEPCO Research Institute has operated it connected to EMS of KPX. This paper discussed the operation strategy of EMS through a study on using 24 MW BESS in AGC operation and propose the improvement of AGC target. It is expected that this paper helps a safe and reliable operation and control of ESS for AGC through its continuous update.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1043-1050
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• 2014

Obsolescent control systems for power systems are evolving into intelligent systems and connecting with smart devices to give intelligence to the power systems. As networks of the control system are growing, vulnerability is also increasing. The communication network of distribution areas in the power system connects closely to vulnerable environments. Many cyber-attacks have been founded in the power system, and they could be more critical as the power system becomes more intelligent. From these environment, new communication network architecture and mitigation method against cyber-attacks are needed. Availability and Fault Tree analysis used to show that the proposed system enhances performance of current control systems.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.21-29
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• 2021

As global environmental regulations have been strengthened, the eco-friendly market has grown rapidly. In the field of aircraft, research on electric vertical take-off and landing aircraft that can enter city centers and perform personal air transportation using electric propulsion is ongoing. For aircraft using electric propulsion methods to operate reliably, electric power thrust systems are a key factor. Electric aircraft require a high power density for propulsion systems with strict limits on volume and weight. The efficient control of inverter systems is essential for achieving high power density. Therefore, in this paper, the characteristics of inverters and motors were analyzed through simulations based on the space vector pulse width modulation (PWM) and discontinuous PWM methods for controlling inverter systems.