• Journal of Power Electronics
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• v.12 no.1
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• pp.33-39
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• 2012

This paper describes operating and capacitor voltage balancing of the modular multilevel converter. The paper focuses on sizing of the cell capacitor and establishes approximate expressions for the capacitor voltage. Simulations and experiments results obtained from three-level modular converter are used to demonstrate its viability in medium voltage applications. It is shown that the modular converter can operate over the full modulation index linear range independent of load power factor.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.216-221
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• 1997

At present, high frequency electronic ballast are widely used to drive the fluorescent lamp at high frequency for improving light quality. The electronic ballast mainly consist of an inverter stage with a load resonant circuit. This paper derives a lamp model consist of a voltage equation and a current equation. The proposed model is useful for an engineer to determine circuits and to analyze the performance of electronic ballast with high frequency operation. Simulation with PSPICE and experimentator and the high power factor of the proposed topology.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.138-141
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• 2008

The effects of design parameters for small scale hydro power(SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on Weibull distribution show that the capacity and load factor of SSHP site had large difference between the variation of shape and scale parameter. Especially, the hydrologic performance of SSHP site due to variation of shape parameter varied more sensitive than the case of variation of scale parameter. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.2
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• pp.111-118
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• 1990

This paper presents a new algorithm of contingency analysis and countermeasure to alleviate the line overloads for electric power systems. In this algorithm, the inverse matrix of the new Jacobian matrix when a contingency occurs, in fastly calculated using the house-holder's Inverse Matrix Modification Lamma (IMML) with the original factor table. The generation outputs are firstly adjusted to alleviate all line overloads occurred by the contingency without tripping loads. If the generation adjustment is not enough anymore to alleviate line overloads, then the control of bus injection power is recommended to quickly alleviate remaining overloads with minimum amount of load tripping and generation read-justing at the termination busbars of the overload lines. The proposed algorithm has been validated in tests on the 6 busbar test system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.6
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• pp.253-258
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• 2000

This paper presents an application of Kohonen neural networks to assess the dynamic security of power systems. The dynamic security assessment(DSA) is an important factor in power system operation, but conventional techniques have not achieved the desired speed and accuracy. The critical clearing time(CCT) is an attribute which provides significant information about the quality of the post-fault system behaviour. The function of Kohonen networks is a mapping of the pre-fault system conditions into the neurons based on the CCTs. The power flow on each line is used as the input data, and an activated output neuron has information of the CCT of each contingency. The trajectory of the activated neurons during load changes can be used in on-line DSA efficiently. The applicability of the proposed method is demonstrated using a 9-bus example.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.614-618
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• 2009

The effects of design parameters for small scale hydro power(SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on KIER model show that the capacity and load factor of SSHP site had large difference between the period. Especially, the hydrologic performance of SSHP site such as design flowrate due to rainfall condition of recent period varied sensitively. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• New & Renewable Energy
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• v.4 no.3
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• pp.15-22
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• 2008

The effects of design parameters for small scale hydro power (SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on Weibull distribution show that the capacity and load factor of SSHP site had large difference between the variation of shape and scale parameter. Especially, the hydrologic performance of SSHP site due to variation of shape parameter varied more sensitive than the case of variation of scale parameter. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.43-49
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• 2008

The effects of design parameters for small scale hydro power(SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on Weibull distribution show that the capacity and load factor of SSHP site had large difference between the variation of shape and scale parameter. Especially, the hydrologic performance of SSHP site due to variation of shape parameter varied more sensitive than the case of variation of scale parameter. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.382-387
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• 2016

This paper deals with the assessment of voltage sags regarding the variation of system operating conditions. In general, voltage sag assessment is performed by assuming the constant operating condition throughout the year. However, the assumption can lead to assessment errors in case of considerable changes of system operation condition. This paper presents a method to estimate ESF(expected sag frequency) considering the operating conditions according to the changes of power demand throughout the year.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.267-272
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• 2009

The effects of design parameters for small scale hydro power(SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on KIER model show that the capacity and load factor of SSHP site had large difference between the period. Especially, the hydrologic performance of SSHP site due to rainfall condition of recent period varied in design flowrate sensitively. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.