• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.462-465
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• 1988

In this paper, it is described that digital back-up control system is developed and applied to the thermal power boiler control system which consists of many kinds of analog electronic cards. Also, by the installation of this system in ulsan power pllant, it was proven to have excellent capabilities of fault detection and digital back-up control.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.1
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• pp.10-19
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• 1990

A fault tolerant control system, in which a digital back-up controller system is added on the existing analog control system, is developed for enhancing reliability of boiler control system in power plant. The digital back-up controller system(DBCS) has a multi-processor structure with capabilities of fault diagnosis, back-up control, self test, and graphic monitoring. Specifically, switching mechanism composed of expandable modules is designed so that back-up controller takes over any faulty control loops and the number of back-up control loops is determined as that of simultaneous faults. A process simulator that simulates the boiler analog control system is developed for safety test and performance evaluation prior to real plant application. DBCS is installed at the Ulsan thermal power plant, and fault tolerant control performance is assured under the faults that some controller modules are pulled out.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.129.1-129.1
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• 2010

Since the commencement of the fuel cell business in 2007, POSCO POWER has been the major supplier of the MCFC (Molten Carbonate Fuel Cell), which is the most commercialized stationary fuel cell system in the world. With its quite, yet active movement, more than 20MW MCFC systems have been installed and are operating in Korea. While trying to localize the components and set up a firm supply chain in Korea to provide more reliable and cost-competitive products to its customers, POSCO POWER is also devoting itself to developing new MCFC application products. One such product is a back-up power system, in which a back-up algorithm is embedded to the present system so that the product can work as a back-up generator in case of grid failure. The technology to enhance load following capability of a stack module is also being developed with the back-up algorithm. Another example is a building application, the goal being to make the present Sub-MW product suitable for urban area. For this, downsizing and modularization are the main R&D scope. The project for developing ship service fuel cell for APU application will launch soon as well. In the project, a system which can operate in marine environment, and reforming technology for liquid logistic fuel will be developed.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.75-87
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• 2019

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using a fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve a high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1289-1291
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• 2000

The operation of Back-To-Back HVDC system for asynchronous connection is described. It can exchange electric power up to 300 MW between separately operated two rower systems, making the interaction on each system minimum. The analysis is done under three different AC transmission lines interconnected to BTB HVDC.

• Proceedings of the Safety Management and Science Conference
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• 1999.11a
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• pp.345-354
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• 1999

A new type of capacitor named "Super Capacitor" has been developed, in which the properties of electric double layer formed at the interface of activated carbon electrode- liquid organic electrolyte is applied. This capacitor is small In size, light in weight, wide In temperature range(-25~$70^{\circ}C$), large in charge-discharge capability and good in voltage preservation. And this super capacitor is applied as a power back-up for electricity failure in volatile memory devices etc., a power source for a short time and a power source for operating actuators. At present the development of high power back-up types of the capacitor system and improvement of their characteristics are being actively conducted in order to find wider applications.lications.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.293-300
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• 2021

This study presents a Power Quality(:PQ) costs calculation methodology based on Value-Based Methodology. A SCDF including Voltage Sag Costs is presented to calculate Sustained Interruption Costs, Momentary Interruption Costs, and Voltage Sags Costs. Authors compared between interruption costs without Back-Up Power Supply and interruption costs with Back-Up Power Supply, and showed reduction of interruption costs by investing Back-UP Power Supply by multi-lateral analyzation. By applying this method to the real system, evaluated and analyzed power quality of the system.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.1
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• pp.20-29
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• 2011

This paper proposes critical load following back-up system using MCFC stack. This system enables MCFC generation system to supply power to critical load without UPS and to generate rated power under grid fault state. This back-up system includes 'Load Leveler' that is connected with 3-phase inverter and is controlled by additional algorithm that includes critical load following. The proposed system and algorithm are verified by computer simulation based on 5kW system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.305-309
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• 2003

In recent large power plants, the excitation system has the static type, which is characterized by the fast response to increase the transient stability. The high capacity excitation systems developed in KEPRI is either a hot back-up, hybrid hot back-up (analog + digital) or triple modular redundant digital type, both well proven by actual tests and applied in commercial operation. The large excitation systems have been developed taking into consideration the parameters of large scale power plants, resulting in high costs and subsequently are supplied at higher prices. When used at small sized power plants, the cost impact is relatively high. As a countermeasure to such a situation, KEPRI has recently developed a reliable, miniature digital excitation system, which is one-board type, convenient and adequate for low-price, small-sized (0.5MW∼200MW) power plants.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.28-34
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• 1987

As a means of improving the reliability of a process control system, a FTCS(Fault Tolerant Control System) is designed and applied to the boiler controller of a thermal power plant. The proposed FTCS has capabilities of fault detection and diagnosis as well as back-up control and bumpless switching. A prototype of FTCS is implemented on an IBM PC as an add-on system and it is experimentally verified by using a boiler process simulator together with simplified analog controllers and a switching unit that an one-fold fault is detected in real time and back-up controller takes over the role of the original controller, controlling the faulty loop.