• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.10
• /
• pp.60-64
• /
• 2015

Many people think that Electric Vehicles(EVs) is the best method to resolve the problems of running out of fossil fuels. But EVs take long time for charging. So, EVs with battery swapping systems(EVBS) are developed to resolve this problem. Nonetheless, EVBS is not spreaded widely because the method of durability test in couplers is not defined. In this study, the evaluation method of durability test in couplers is defined by some standards and the measurement uncertainty is used to increase the reliability of EV couplers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.511-518
• /
• 2008

The Engineering Test Satellite VIII(ETS-VIII) of Japan Aerospace Exploration Agency(JAXA) uses a 20mN class xenon ion engine subsystem(IES) for North-South Station Keeping(NSSK). The IES was modified for a larger satellite with longer lifetime based on the former IES. ETS-VIII, a three-ton class geosynchronous satellite with 10 years bus lifetime, was launched 18 Dec. 2006 JST; it reached the planned orbit and all bus systems were checked out. The IES showed good results and is now under normal operation. The total accumulated operation time of the IES in orbit was about 2300 hours till $19^{th}$ Dec. 2007.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.10
• /
• pp.509-516
• /
• 2001

Isolated phase bus(IPS) has a special structure for carrying large current generated by a generator to a main transformer. In the analysis of IPB, the understanding of the magnetic field distribution generated by large current is important. Especially, while the bus conductor current is flowing, almost same amount of current as bus conductor current is induced in the enclosures under the influence of time varying magnetic field, and therefore the large electric loss and the deterioration of insulating capability might occur due to Joule heating effect. Hence for the optimal design of IPB satisfying the condition to minimize the loss, the accurate analysis of magnetic field distribution and the eddy current characteristics of three phase isolated phase bus have been investigated. In the analysis of time varying magnetic field, instead of finite difference method(FDM) which is generally used, finite element method with phasor concept is investigated under the assumption that the bus current is purely sinusoidal. The characteristics is studied along the phase angle by comparing the effect of eddy current on the magnetic field distribution with the case that eddy current is not considered, and also the effect of material, thickness and radius of enclosure on the eddy current distribution is discussed.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.20-25
• /
• 2011

This paper analyzed the application of Superconducting Fault Current Limiter (SFCL) on 22.9 [kV] bus tie in a power distribution system. Commonly, the parallel operations of power main transformers offer a lot of merits. However, when a fault occurs in the parallel operation of power main transformer, the fault currents might exceed the interruption capacity of existing protective devices. To resolve this problem, thus, the SFCL has been studied as the fascinating device. In case that, Particularly, the SFCL could be installed to parallel operation of various power main transformers in power distribution system of the Korea Electric Power Corporation (KEPCO) on 22.9 [kV] bus tie, the effect of the resistance of SFCL could reduce the increased fault currents and meet the interruption capacity of existing protective devices by them. Therefore, we analyzed the effect of application and proposed the proper impedance of the R-type SFCL on 22.9 [kV] bus tie in a power distribution system using PSCAD/EMTDC.

• Transactions on Electrical and Electronic Materials
• /
• v.17 no.1
• /
• pp.1-6
• /
• 2016

Ensuring the secure operation of power systems has become an important and critical matter during the present time, along with the development of large, complex and load-increasing systems. Security constraints such as the thermal limits of transmission lines and bus-voltage limits must be satisfied under all of a system’s operational conditions. An alternative solution to improve the security of a power system is the employment of Flexible Alternating-Current Transmission Systems (FACTS). FACTS devices can reduce the flows of heavily loaded lines, maintain the bus voltages at desired levels, and improve the stability of a power network. The Unified Power Flow Controller (UPFC) is a versatile FACTS device that can independently or simultaneously control the active power, the reactive power and the bus voltage; however, to achieve such functionality, it is very important to determine the optimal location of the UPFC device, with the appropriate parameter setting, in the power system. In this paper, a genetic algorithm (GA) method is applied to determine the optimal location of the UPFC device in a network for the enhancement of the power-system loadability and the minimization of the active power loss in the transmission line. To verify our approach, simulations were performed on the IEEE 14 Bus, 30 Bus, and 57 Bus test systems. The proposed work was implemented in the MATLAB platform.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2348-2356
• /
• 2011

In recent years, many researches for DC power distributed system (PDS) are being preformed and the importance of the DC PDS is more and more emphasized. Furthermore, in the railway system, the DC PDS is used in subway station lighting, facilities, etc. In the DC PDS, DC bus voltage instability may be occurred by the operation of multiple parallel loads such as pulsed power load, motor drive system, and constant power loads. Thus, good quality and high reliability for electric power are required and voltage bus conditioner (VBC) may be used the DC PDS. The VBC is a DC/DC converter for mitigation of the bus transients. In this paper, adaptive controller is designed. The simulation results by PSIM are presented for validating the proposed control algorithm.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.149-152
• /
• 2005

The DC power-bus' resonance is frequently attributed to EMI sources in the PCBs. Subsequently, it will ruin the digital signal integrity within one system or between adjacent systems in the form of conducted or radiated emission. Hence, since it is of importance to examine the PCB's emission, this paper sheds a light on the radiated emission from the power-bus with regards to its resonance modes. A full-wave analysis method is used to calculate the impedance and radiated electric fields and is validated by physics and an EM analysis tool.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.4
• /
• pp.694-703
• /
• 2013

In electric power system, the line stability indices adopted in most of the instances laid stress on variation of reactive power than real power variation of the transmission line. In this paper, a proposal is made with the formulation of a New Voltage Stability Index (NVSI) which originates from the equation of a two bus network, neglecting the resistance of transmission line, resulting in appreciable variations in both real and reactive loading. The efficacy of the index and fuzzy based load flow are validated with IEEE 30 bus and Tamil Nadu Electricity Board (TNEB) 69 bus system, a practical system in India. The results could prove that the identification of weak bus and critical line in both systems is effectively done. The weak area of the practical system and the contingency ranking with overloading either line or generator outages are found by conducting contingency analysis using NVSI.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.4
• /
• pp.263-270
• /
• 2021

Active AC/DC converters with PWM operation are utilized to regulate rectified DC bus voltage of a permanent magnet synchronous generator in the maritime DC power system. A DC bus voltage regulation strategy that exploits the six-step operation is proposed in this study. Compared with that of the PWM operation, switching loss of the converter can be significantly reduced under the six-step operation. Moreover, conduction loss can also be reduced due to the high modulation index and reduced flux-weakening current of the six-step operation. A controller is used for the proposed DC bus voltage regulation strategy to verify its validity with the simulation and experimental setup. The simulation and the experimental test results showed that the converter loss reduces to a maximum of 70% and 19%, respectively.

• Journal of the Korean Vacuum Society
• /
• v.9 no.3
• /
• pp.233-236
• /
• 2000

The structural, electrical and chemical characteristics of Al alloy thin film with low impurity concentrations AlW deposited by using dc magnetron sputtering deposition are investigated for the applications as data bus line in the TFT-LCD panel. The deposited thin films show the decrease of resistivity and the increase of grain size after the RTA at $300^{\circ}C$ for 20 min.. Moreover, the resistivity of AlW does not show appreciable grain size dependence after RTA. It is concluded that the decrease of resistivity after RTA is due to the increase of grain size. The annealed AlW is found to be hillock free. And for investigating chemical attack in TFT-LCD etching processing the electric potential of AlW alloy for Ag/AgCl were investigated by cyclic voltammetry. When W wt.% of AlW alloy was higher than about 3%, the electric potential of AlW was more positive than ITO's. Therefore AlW alloy thin film can be propose to use for data bus line.