• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.381-384
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• 2008

This paper presents an operational technique to maximize profit of a cogeneration power plant. To minimize errors in a loss and gain analysis of a cogeneration power plant, the energy sale profit in the cost-based-pool electric power trade market, the heat sale profit, and the supplementary fund profit for electric power industry are taken into consideration. The objective is to optimize the heat-electric power ratio to maximize profit of a cogeneration power plant. Furthermore, the constrained bidding technique to optimize heat-electric power ratiocan be obtained. Profits from of a cogeneration power plant are composed of three categories, such as the energy sale profit in the cost-based-pool electric power trade market, the heat sale profit, and the supplementary fund profit for electric power industry. Profits of a cogeneration power plant are varied enormously by the operation modes. The profits are mainly determined by the amount of constrained heat generation in each trading time. And the three profit categories arecoupled tightly via the heat-electric power ratio. The result of this case study can be used as a reference to a cogeneration power plant under the power trading system considered in this case.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.485-487
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• 2001

Electric power has traditionally been supplied to the demander through power generation, its transmission, and final distribution system. It is, however, expected that the various dispersed power system will be located near demanders and act as a power source based on the efficient management of electric power demanders and the optimal utilization of substitute energy. More stable electric power and efficient utilization of various power sources can be guranteed through the connection of the dispersed power system into the existing power system. It is the purpose of this study that, in the case of the connection of dispersed power system into the existing distribution line, effects of the connection on the power quality and plans for protection of power equipments are discussed and solutions of them are proposed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.1
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• pp.18-24
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• 2005

Various problems such as the increase of the power loss and the voltage instability may often occur in the case of low load power factor. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the comprehensive management of reactive power a troublesome problem, so that the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost is derived and it is used for determining the locations of reactive power compensation devices effectively and for enhancing the load power factor appropriately. In addition, the voltage variation penalty cost is introduced and the integrated costs including the voltage variation penalty cost are used for determining the value of the load power factor from the point of view of the economic investment and voltage regulation. It is shown through the application to a large-scale power system that the load power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.

• New & Renewable Energy
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• v.18 no.3
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• pp.32-42
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• 2022

Rapid spread of intermittent renewable energy has amplified the instability and uncertainty of power systems. The Korea Power Exchange (KPX) promoted efficient management by opening the power brokerage market in 2019. By combining small-scale intermittent renewable energy with a flexible facility through the power brokerage market, the KPX aims to develop a virtual power plant system that will allow the conversion of existing intermittent renewable energy into collective power plants. However, the participation rate of renewable power owners in the power brokerage market is relatively low because other markets such as the small solar power contract market or the Korea Electric Power Corporation power purchase agreement are more profitable. In this study, we used a choice experiment to determine the attributes affecting the participation rate in the power brokerage market for 113 renewable power owners and estimate the value of the power brokerage market. According to the estimation results, a low smart meter installation cost, low profit variations, long contract periods, and few clearances increased the probability of participation. Moreover, the average value of the power brokerage market was estimated to be 2.63 million KRW per power owner.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.9
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• pp.273-278
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• 2014

Recent use of electricity during peak hours electricity supply-demand imbalance is inevitable that limit power use force. Therefore, in this paper, a circuit of parallel power operation equipment for peak power reduction which saves the power to electricity storage device during the non-peak power time and supply from the storage power during the expected power shortages time is designed Through this circuitry, the peak power of the commercial power supply with the parallel operation and connection of the commercial power supply and the power supply of the inverter from electricity storage that is a key feature of PRS(Peak power Reduction System) can be controlled. In addition, in order to increase the efficiency, a Transless Power Circuit DC-AC inverter is developed. Moreover, a variable impedance control is applied to the storage of electric power of an Uninterruptible Power Supply associated with a commercial power source.

• The Transactions of the Korean Institute of Power Electronics
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• v.1 no.1
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• pp.1-6
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• 1996

Recent trends of the power electronic industry in China have been summarized in this paper. Based on the applications of the power electronic products in the chinese industries the production trends of power semiconductor devices, drives, power supplies, power electronic industry used in power systems in China have been briefly reviewed.

• KIEE International Transactions on Power Engineering
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• v.3A no.3
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• pp.124-129
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• 2003

As the power industry moves towards open competition, there has been a call for methodology to evaluate power system reliability by using composite interruption cost. This paper presents algorithms to evaluate the interruption cost of distribution power systems by taking into consideration the failure source and the composite customer interruption cost. From the consumer's standpoint, the composite customer interruption cost is considered as the most valuable index to estimate the reliability of a power distribution system. This paper presents new algorithms that take into account the load by customer type and failure probability by distribution facilities while calculating the amount of unserved energy by customer type. Finally, evaluation results of unserved energy and system interruption cost based on composite customer interruption cost are shown in detail.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.499-500
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• 2008

In this paper, we design and implement the monolithic power factor correction IC for system power modules using a high voltage(50V) CMOS process. The power factor correction IC is designed for power applications, such as refrigerator, air-conditioner, etc. It includes low voltage logic, 5V regulator, analog control circuit, high-voltage high current output drivers, and several protection circuits. And also, the designed IC has standby detection function which detects the output power of the converter stage and generates system down signal when load device is under the standby condition. The simulation and experimental results show that the designed IC acts properly as power factor correction IC with efficient protective functions.

• Journal of Power Electronics
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• v.12 no.3
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• pp.487-494
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• 2012

A new low cost high power density photovoltaic power conditioning system (PV PCS) with an energy storage system is proposed in this paper. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and the battery charger/discharger. Despite the reduced power stage, the proposed system can achieve the same performance in terms of maximum power point tracking and battery charging/discharging as the conventional system. When a utility power failure happens, the proposed system cannot perform maximum power point tracking at the UPS mode. However, the predetermined battery voltage near the maximum power point of the PV array can effectively generate a reasonable PV power even at the UPS mode. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, a theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.284-286
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• 2003

The low load power factor causes various problems such as the Increase of the power loss and the voltage instability. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the integrated management of ractive power troublesome, from which the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost and integrated costs are used for determining the locations and capacities of reactive power compensation devices effectively and for enhancing the load power factor appropriately. It is shown through the application to a small-scale power system that the system power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.