• KIEE International Transactions on Power Engineering
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• v.11A no.4
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• pp.27-32
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• 2001

This paper presents a concept of reactive reserve based contingency constrained optimal power flow (RCCOPF). RCCOPF for enhancement of interface flow limit is composed of two modules, which are the modified continuation power flow (MCPF) and reactive optimal power flow (ROPF). In RCCOPF, two modules are repeatedly performed to increase interface flow margins of selected contingent states until satisfying the required enhancement of interface flow limit. In numerical simulation, a simple example with New England 39-bus test system is shown.

• KIEE International Transactions on Power Engineering
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• v.11 no.X00
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• pp.27-32
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• 2001

This paper presents a concept of reactive reserve based contingency constrained optimal power flow (RCCOPF). RCCOPF for enhancement of interface flow limit is composed of two modules, which are the modified continuation power flow (MCPF) and reactive optimal power flow (ROPF). In RCCOPF, two modules are repeatedly performed to increase interface flow margins of selected contingent states until satisfying the required enhancement of interface flow limit. In numerical simulation, a simple example with New England 39-bus test system is shown.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.715-726
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• 1999

This paper estimates the capacity of shunt type active power filters(APF) for harmonic/reactive power compensation with a thyristor converter load. The base capacity requirement of APF is defined for idealized converter load current waveform and the effect of commutation overlap on the APF capacity is examined. The APF capacity required for reactive power compensation in addition to the harmonic elimination is estimated to give maximum achievable power factor for various operating condition of the partially-loaded thyristor converter. The method of current limit of APF is introduced, and it is shown that the APF capacity can be considerably reduced by deliberately limiting the peak current while maintaining the filtering performance to meet the level std 519 regulation.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.271-273
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• 2005

In KEPCO(Korea Electric Power Corporation)system, 40% of total loads is ones of metropolitan area and large staled generation plants are located out of metropolitan area. Therefore, to decide the maximum power transfer capability of interface line between the regions is essential for planning, control and operation of efficient transmission system. For this reason, prior study suggested calculating the limit of our interface line from the side of voltage stability. However, the presented plan had a limit partially to apply practice power system. Therefore this paper suggests a algorithm that change the generation output as the merit order instead of prior method that distribute according to proportion of present output. This method could be applied closer to practice than the existing algorithm because it consider generation cost.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1790-1806
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• 2015

Utility-based routing is a special type of routing approach using a composite utility metric when making routing decisions in ad hoc and sensor networks. Previous studies on the utility-based routing all use fixed retry limit and a very simple distance related energy model, which makes the utility maximization less efficient and the implementation separated from practice. In this paper, we refine the basic utility model by capturing the correlation of the transmit power, the retry limit, the link reliability and the energy cost. A routing algorithm based on the refined utility model with adaptive transmit power and retry limit allocation is proposed. With this algorithm, packets with different priorities will automatically receive utility-optimal delivery. The design of this algorithm is based on the observation that for a given benefit, there exists a utility-maximum route with optimal transmit power and retry limit allocated to intermediate forwarding nodes. Delivery along the utility-optimal route makes a good balance between the energy cost and the reliability according to the value of the packets. Both centralized algorithm and distributed implementations are discussed. Simulations prove the satisfying performance of the proposed algorithm.

• Analytical Science and Technology
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• v.7 no.3
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• pp.253-260
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• 1994

Analytical characteristics of low power-low flow inductively coupled plasma-atomic emission spectometry(ICP-AES) has been studied. Although the net intensity of the low power ICP is lower than the moderate power ICP, the signal to background ratio becomes higher since the background intensity decreases with decreasing the RF power. The detection limit of the low power ICP is comparable with that of the moderate power ICP. The dynamic range of the calibration curve of the low power ICP is $10^4{\sim}10^5$. The ionization interferences by alkali metals increase with increasing the carrier gas flow rate, but the effects are not varied significantly with the RF power.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.927-935
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• 1994

Detailed analysis of the commutation circuit of the proposed wide-frequency current source inverter is given. In this inverter a spike-limit circuit and a precommutation circuit are used. The spike-limit circuit is intended to limit spike voltage which is arising during commutation time in a current source inverter, and the precommutation circuit to reuse the energy which flows from main inverter to spike-limit circuit during commutation time to aid commutation. Thus voltage stress of main thyristor is minimized. Since this inverter can be made up of thyristors for phase control, it has some advantage in high voltage and high power application.

• KIEE International Transactions on Power Engineering
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• v.12A no.1
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• pp.15-19
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• 2002

The power transfer capability is determined by the thermal, dynamic stability and voltage limits of the generation and transmission systems. The voltage stability depends on the reactive power limit and it affects the power transfer capability to a great extent. Then, in most load flow analysis, the reactive power limit is assumed as fixed, relatively different from the actual case. This paper proposes a method for determining the power transfer capability from a static voltage stability point of view using the IPLAN which is a high level language used with PSS/E program. The f-V curve for determining the power transfer capability is determined using Repeated Power Flow method. It Is assumed that the loads are constant and the generation powers change according to the merit order. The maximum reactive power limits are considered as varying similarly with the actual case and the effects of the varied maximum reactive power limits to the maximum power transfer capability are analyzed using a 5-bus power system and a 19-bus practical power system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.692-698
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• 1999

This paper analyzes the effect of DGS(Dispersed Generation System) on the voltage regulation of the traditional distribution system of which the voltage is controlled by the bank LDC(Line Drop Compensator). Through the simulation results for 22.9kV class distribution system with DGSs, some general relationships among the operating power factor and introduction limit of DGS, and the sending-end reference voltage determined by internal setting coefficients of the LDC are derived. Those relationships are that the introduction limit of DGS increases as the power factor of DGS goes from lagging to leading and also as the allowance of the sending-end reference voltage increases. From the relationships, a operation method of the power distribution system integrated with DGSs is proposed from the view point of the operating power factor of DGS and new voltage regulation method.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.297-304
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• 2015

A conventional single-phase high-power system typically generates a large AC line input current at universal 90 VAC condition. Sometimes, this phenomenon can block the Earth Leakage Circuit Breaker (ELCB), which causes problems. Replacing power facilities is essential to ensure smooth operations. Thus, this paper proposes a method that can drive higher power than the limit of conventional power facilities. The proposed method can reduce the large AC line input current by limiting the input power of Power Factor Correction (PFC). An additional battery circuit can supplement the power deficiency. Specifically, a bidirectional converter with charging and discharging functions was adopted for the battery circuit. Finally, the validity of the proposed system could be confirmed by modal analysis and simulation, and an experiment in 2 KW condition was implemented with a prototype sample as well.