• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.707-710
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• 1996

This paper is to build and develop the generation schedule program to provide a stable power supply and economic operation of power generation system. A practical algorithm is presented for solving the thermal unit commitment problem which is one of very important areas in economic operation of power system. This algorithm is based on priority ordering by the unit generation cost and it is shown that the operation cost of chosen sets of generators is the minimum. The proposed method is proven to be very practical, accurate and efficient in a KEPCO system.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.30-34
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• 2005

Due to old Toshiba EMS's database size limit and hardware old aging, KPX(Korea Power Exchange) had introduced New EMS from AREVA(old ALSTOM) in July 2002. After then KPX had committed many man power and time to normalize EMS NA(Network Analysis) functions for using real power system. At initial stage, to normalize State Estimator which is the backbone of all other NA functions and DTS(Dispatcher Training Simulator}, KPX had corrected numerous topology errors, network model errors, non-scanned and wrongly scanned SCADA measured errors. After SE function study, running test and tuning, State Estimator could finally have been run properly and stably from June 2003. Based on SE running, KPX had normalized real time Contingency Analysis, and study mode Power Flow, STNET and DTS. From early 2004, dispatchers have been trained to use NA and DTS for the purpose of stable SE running, NA operation & results reading and urgent equipment outage reviewing. EMS NA have been greatly contributed to operate real time power system stably. Above NA normal operation by KPX own efforts under the no experience of NA running, KPX made a good precedent. This paper is intended to introduce EMS NA normalization process, operation status, and etc in Korea power system operation.

• Journal of Power Electronics
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• v.9 no.2
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• pp.300-307
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• 2009

In this paper, design and control is proposed for a four input-series-output-series-connected ZVS full bridge converter for the photovoltaic power conditioning system (PCS). The novel topology for a photovoltaic (PV) DC/DC converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. The control scheme, including an input voltage controller is proposed to achieve equal sharing of the input voltage as well output voltages by a four series connected module. Design methods for ZVS power stage are also introduced. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three DC/DC converters with a 25-kW power rating and uses only one-third of the total PV PCS power. The 25-kW prototype PV DC/DC converter is introduced to verify experimentally the proposed topology. In addition, an experimental result shows that the proposed topology exhibits good performance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.113-118
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• 2014

Tidal power is one of new and renewable energy sources. Tidal power is generated by using the gap in the water level between the water outside and inside the embankment. All tidal power plant in Korea were being operated by import of turn-key from abroad. The know-how and technology which are the most important to build predictive control system has become increasingly difficult to obtain from advanced countries because most of them avoid to transfer, which the domestic development of the control system is needed. In this paper, a study on start stop system at water turbine-generator for tidal power plant at the beginning of development was presented. For improvement the efficiency and develope of core technology of the start stop system, the technique and characteristics of tidal power, modeling, maximum generation calculation method, and optimal control of joint control system in Sihwa tidal power plant were studied.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.357-364
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• 2015

The power system configuration is changed to solve increasing power demand. This changes in power system configuration with mesh-, network grid generate the problem of fault current increase. Superconducting fault current limiter (SFCL) has been expected the one of the solutions to solve this problem. And there has already been reported much to the application and research of SFCL in the power distribution system. However, the application and research of SFCL are insufficient in a transmission power system. Also, the fault current limiting effect by the SFCL varies with installation location of SFCL. Therefore, this paper constructed the power transmission system through experiment and analyzed installation location method of SFCL using the current rate of each circuit breaker (CB) according to fault location.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.57-58
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• 2008

Recently, several kinds of superconductivity applications are implemented and evaluated in the utility power networks. The protection system for HTS(High Temperature Superconducting) power devices safe operation has not been established yet. For the protection of the HTS apparatus, a better understanding of the quench properties against fault current and appropriate protection devices are required. In this study, an algorithm of protection system is developed with respect to HTS power cable. The protection system of HTS power cable was analyzed in the simulated power system. Results obtained from simulation will provide much more decisive data in order to design a certain superconducting power device, and can give a good information for the installation in power system.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.27-33
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• 2012

Internet Data Centers (IDC), as essential facilities for modern IT industry, typically have scores of MW of concentrated electric loads. Uninterruptible Power Supplies (UPS) are necessary for the power feed system of IDCs because of stable power requirement. Thus, conventional AC power feed systems of IDCs have three cascaded power conversion stages such as (AC-DC), (DC-AC), and (AC-DC), which results in very low conversion efficiency. On the contrary, DC power feed systems need just a single power conversion stage (AC-DC) supplying AC mains power to DC server loads, which gives comparatively high conversion efficiency and reliability. This paper compares the efficiencies between 220V AC power feed system and 300V DC power feed system on equal load conditions which were established in Mok-Dong IDC of Korea Telecom company (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is around 15% higher than that of the 220V AC power feed system.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.75-76
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• 2007

Several kinds of High Temperature Superconducting(HTS) power cables have already been developed and evaluated for use in the utility power network. HTS power cable is expected to be used as a very powerful energy delivery system supplying electric power for densely populated cities in the near future, because HTS power cable is capable of the high current density delivery with low AC loss and the size effect comparing with the conventional cable whose capacity is same. Before applying the HTS power cable to real utility network system analysis should be carried out by some simulation tools. Hereby the electrical power system analysis is very important for the practical use of HTS power devices. In this paper, authors propose a real-time simulation method which incorporates a real HTS tapes into the simulated 22.9kV utility power network system using Real Time Digital Simulator(RTDS). For the simulation analysis, a test sample of HTS tapes was actually manufactured, and the transient phenomenon of HTS power cable system was analyzed in the simulated utility power network.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.778-780
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• 1998

The distributied control system consists of PCS(Process Control System), OIS(Operator Interface System), Communication Network and EWS(Engineering Workstation). This parer describes the system structures and the technological trends of domestically developed distributied control system (DCS).

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.685-686
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• 2007

This paper presents an application of power system fault diagnostic algorithm for the PEFP Proton Accelerator Research Center using neural network. Proposed fault diagnostic system is constructed by the radial basis function (RBF) neural network because it has the capabilities of the pattern classification and function approximation of any nonlinear function. Proposed system identifies faulted section in the power system based on information about the operation of protection devices such as relays and circuit breakers. In this paper, parameters of the RBF neural networks are tuned by the GA-TS algorithm, which has the global optimal solution searching capabilities. To show the validity of the proposed method, proposed algorithm has been tested with a practical power system in Proton Accelerator Research Center of PEFP.