• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1052-1059
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• 2018

This paper deals with commutation failure of the line-commutated converter high voltage direct current (LCC HVDC) system caused by a three phase fault in the ac power system. An analytic calculation method is proposed to estimate the maximum permissible voltage drop at the LCC HVDC station on various operating point and to assess the area of vulnerability for commutation failure (AOV-CF) in the power system based on the residual phase voltage equation. The concept is extended to multi-infeed HVDC power system as the area of severity for simultaneous commutation failure (AOS-CF). In addition, this paper presents the implementation of a shunt compensator applying to the proposed method. An analysis and simulation have been performed with the IEEE 57 bus sample power system and the Jeju island power system in Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.73-79
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• 2007

In order to analyze the potential rise of grounding systems installed in buildings, a hemispherical grounding simulation system was studied. Potential rise was measured and analyzed regarding the shape and distance of the grounding electrodes by using this system. The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured in real time by the horizontal moving probe of be potentiometer. The test grounding electrodes were fabricated through reducing the grounding electrode installed in real buildings such as the ground rod, grounding grid and so on. The potential rise was displayed in a two-dimensional profile and was analyzed regarding the shapes of the ground electrodes. The potential rise of the grounding grid combined with a ground rod was the lowest of every grounding electrode tested. The proposed results can be applicable to evaluating ground potential rise in grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent electrical disasters.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1818-1820
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• 1999

This paper presents direct ${\mu}c$-Si:H thin film growth on the glass substrates using RPCVD system (remote plasma chemical vapor deposition) in low temperature. Hydrogenated micro-crystalline silicon deposited by RPCVD system in low temperature is very useful material for photovoltaic devices, sensor applications, and TFTs (thin film transistors). Varying the deposition conditions such as substrate temperature, gas flow rate, reactive gas ratio $(SiH_4/H_2)$, total chamber pressure, and rf power, we deposited ${\mu}c$-Si:H thin films on the glass substrates (Corning glass 1737). And then we measured the structural and electrical properties of the films.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.441-446
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• 2013

A thermal model of power modules based on the physical dimension and thermal properties is proposed in this paper. The heat path in the power module is considered as a one-dimensional heat transfer in the model. The method of the parameters extraction for the model is given in the paper. With high speed and accuracy, the thermal model is suit for electrothermal simulation. The proposed model is verified by experimental results.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.278-280
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• 1996

This paper presents a high performance AC propulsion system for electric car to improve traction capability. The presented VVVF inverter was composed of as GTO thyristor and the the controller was fully digitalized by using 32bit DSP. The improved PWM algorithms and the new adhesion control were adapted to improve traction characteristics. This system could be possible the higher reliability and flexibility. The field test results showed the higher performances characteristics of the presented system.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.145-147
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• 1996

Traction Motor is being transferred to the squirrel cage induction motor from D.C motor, by the improved power semiconductors like GTO, IGBT, etc. In the Induction Motor, inverter system must be used for delivering variable voltage variable frequency. But, by pulsating in the system the harmonics would be produced, and that cause the torque ripple and enfeeble the dynamic characteristics of the motor. So, to use the inverter system, we should take the torque ripple into consideration. To minimize the torque ripple in the VSI fed Traction Motor, the optimal pulsating was presented in this paper. By using the SPWM(Sinusoidal Pulse Width Modulation) method, feeding the appropriate pulse, we can minimize the torque ripple and improve the transient response.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.329-334
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• 2007

In this paper, a new load flow algorithm is proposed on the basis of distributed load modeling in radial distribution networks. Since the correct state data in the distribution power networks is basic for all distribution automation algorithms in the Distribution Automation System (DAS), the distribution networks load flow is essential to obtain the state data. DAS Feeder Remote Terminal Units (FRTUs) are used to measure and acquire the necessary data for load flow calculations. In case studies, the proposed algorithm has been proven to be more accurate than a conventional algorithm; and it has also been tested in a simple radial distribution system.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2126-2127
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• 2011

This paper describes the analysis of deterioration characteristics for connection factor according to connection method of grounding system. The connection method of grounding system is specified in IEC standard. In order to analyze the deterioration characteristics for connection factor, deterioration test was carried out when the connection factor was buried in salt water and underground. The test connection factors were C-type sleeve, clamp, and exothermic welding. As a consequence, most of the connection factor was corroded, and the electrical resistance decreased after deterioration. The analytical results can be used to establish the safety of grounding system.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.732-734
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• 2000

In this paper, we designed and made an experiment on a general analog data acquistion system. which used $\mu$-controller. Using the general purpose $\mu$-controller and simple algorithm. we could easily acquire the state of physical system and convert analog to digital data which is possible digital processing. Finally, we realized the RS232 serial communication system for more complex data processing from PC.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1951-1952
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• 2006

To effectively deal with video data, a semantic-based retrieval scheme that allows for processing diverse user queries and saving them on the database is required. In this regard, this paper proposes a semantic-based video retrieval system that allows the user to search diverse meanings of video data for electrical safetyrelated educational purposes by means of automatic annotation processing. If the user inputs a keyword to search video data for electrical safety-related educational purposes, the mobile agent of the proposed system extracts the features of the video data that are afterwards learned in a continuous manner, and detailed information on electrical safety education is saved on the database. The proposed system is designed to enhance video data retrieval efficiency for electrical safety-related educational purposes.