• Journal of Power Electronics
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• v.19 no.4
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• pp.1020-1033
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• 2019

This paper presents a control strategy to enhance the accuracy of reactive power sharing between paralleled three-phase inverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significant differences between inverters connected to a microgrid has been solved, the accuracy of the reactive power sharing in an islanded microgrid is increased, the voltage droop slope is tuned to compensate for the mismatch of voltage drops across the line impedances by using an enhanced droop controller. The proposed method ensures accurate power sharing even if the microgrid has local loads at the output of the inverters. The control model has been simulated by MATLAB/Simulink with two or three inverters connected in parallel. Simulation results demonstrate the accuracy of the implemented control method. Furthermore, in order to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Results obtained from the experimental setup verify the effectiveness of the proposed method.

• Korean System Dynamics Review
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• v.7 no.1
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• pp.67-90
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• 2006

A series of system dynamics model was developed for forecasting demand and supply of human resource in the electricity industry. To forecast demand of human resource in the electric power industry, BLS (Bureau of Labor Statistics) methodology was used. To forecast supply of human resource in the electric power industry, forecasting on the population of our country and the number of students in the department of electrical engineering were performed. After performing computer simulation with developed system dynamics model, it is discovered that the shortage of human resource in the electric power industry will be 3,000 persons per year from 2006 to 2015, and more than a double of current budget is required to overcome this shortage of human resource.

• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.79-84
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• 2005

In many countries, the electric power industry is undergoing significant changes known as deregulation and restructuring. These alterations introduce competition in generation and retail and require open access to the transmission network. The competition of the electric power industry causes many issues to surface. Among them, unbundling of the transmission service is probably the most complicated as it is a single and integrated sector and the transmission revenue requirement must be allocated to market participants in a fair way. In these situations, it is valuable to research the methodologies to allocate transmission usage. The power tracing method offers useful information such as which generators supply a particular load or how much each generator (load) uses a particular transmission line. With this information, we can allocate required transmission revenue to market participants. Recently, several algorithms were proposed for tracing power flow but there is no dominant power tracing method. This paper proposes a power tracing method based on graph theory and complex-current distribution. For practicability, the proposed method for transmission usage allocation is applied to IEEE 30 buses and compared with the method proposed by Felix F.Wu.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.3
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• pp.194-198
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• 2016

The electric power industry have recently been building out Smart Grids, a two-way electricity grid that connects power consumers and producers to a network that enables one to respond quickly to any eventuality. The construction of a two-way electricity grid means that the power control process becomes unified, from what used to be separate processes that originate individually from the consumption phase and the production and supply phases. The role of power control that takes place within each section of the power system may be independent. However, this does not mean the independent control sections are operated individually, but are configured to meet a single target and purpose. Each control section possesses enough degree of independency to respond to eventualities that may occur within different stages of the power system, but at the same time, possesses unified system elements for the stability of the entire power system. From this perspective, Smart Grids are widely regarded as the most rational power industry operation plan. A variety of different control and communication systems can be applied for an effective deployment of Smart Grids. Recently, we have seen systems such as PMS(Power Management System) and PAS(Process Automation System) applied in the deployment of Smart Grids, which are developed from the techniques utilized in the industry. The PMS is attracting particular attention for its power operations management ability. In this study, we propose plans for improvement in the rational development of power system controls through case studies of live PMS operations.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.186-192
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• 2005

As the power industry moves towards open competition, there has been a call for methodology to evaluate power system reliability by using customer interruption costs. This paper presents an evaluation of the interruption costs for public customers in Korea using customer survey methodology. When various research results are examined, the evaluation of direct interruption costs becomes much more simplified. Especially, in the case of public customers, it is known that the evaluation of direct interruption costs is more useful. Accordingly, this paper selected the customer survey method to evaluate the interruption costs for public customers in Korea considering interruption and customer characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2150-2156
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• 2007

According as level of industry develops day after day, electricity load system of industry requires high level control, effectiveness and high efficiency. Among supply and control unit of suitable power supply in these load characteristic, inverter systems of constant current regulate is used widely control of lighting and electric heating system. But, problems that power factor deterioration and fast response of control, efficiency, harmonics and etc are still remain. Therefore, in this paper proposed an inverter systems with constant current regulation and power factor correction (PFC) circuit for lighting and beaconing of aerodromes. The effectiveness of the proposed system confirmed through experimental results of 10[kW] power supply system.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.96-96
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• 2003

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.91-93
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• 2004

This study presents recent trends on the on-line monitoring and diagnostic systems for oil-immersed transformers. Specially, our system on Yeo Su thermal power plant is introduced for high sensitivity and accuracy of ours. It is combined with communication networks to provide an on-line remote monitoring system. Several alarm criteria are formulated to enable a superimposed monitoring system to perform decisive action. The reasons for monitoring the condition and maintaining the health of electrical apparatus were discussed. The experience at the fields and the criteria for the judgment are also discussed in detail.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.3-5
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• 2005

With the paradigm changes of electric power industry, such as deregulation, CO2 Trade, TBT so on, new requirements of power market force to develope fusion power technology. Korea power industry, which is much dependent on international trade, needs to build stretegic infrastructure to meet the energy shortage and digital society era. This Paper suggests the mid-long term target to build power industry infrastructure to adapt the new paradigm of power world.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1304-1312
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• 2009

The purpose of this study is to build promotive measures and to develop alternative policies of DG(Distributed Generation) by finding and analysing effects of four business environment factors related to DEPB(District Electricity Power Business) on boosting DG. In this study, four business environment factors, which are the electric power industry restructuring, electricity tariff and pricing structure, regulations for DEPB, and conflicts of stake-holding groups, are considered as independent variables. And promotion factors of DG including small CHP(Combined Heat and Power) generation, which is outcome of DEPB, are considered as dependent variables. But dependent variables including booming of new renewable energy generation due to green energy pricing incentives, the electric power industry restructuring, and electricity tariff and pricing policies were separatively considered. In this study, some policies were proposed reflecting research results of empirical demonstrative analysis, previous studies, overseas cases, etc.