• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.50 no.6
• /
• pp.265-274
• /
• 2001

Recently, the operation of power systems has become more difficult because the peak demand load is increasing continuously and the daily load factor is getting worse and worse. Also, the consideration of deregulation and global environment in electric power industry is required. In order to overcome those problems, a study on the planning and operation in power systems of dispersed generating sources such as fuel cell systems, photovoltaic systems and wind power systems, has been performed energetically. This paper presents a method for determining an optimal operation strategy of dispersed co-generating sources, especially fuel cell generation systems, considering thermal supply as well as electric power supply. In other words, the optimal operation of those sources can be determined easily by the principle of equal incremental fuel cost and the thermal merit of those sources can be also evaluated quantitatively through Kuhn-Tucker's optimal conditions. In additions, an priority method using the comparison of total cost at the peak load time interval is presented in order ot select the optimal locations of those sources. The validity of the proposed algorithms is demonstrated using a model system.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.08a
• /
• pp.42.6-43
• /
• 2008

• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.533-546
• /
• 2018

This study proposes a comprehensive mathematical model that includes coil-system circuit and loss models for power converters in wireless power transfer (WPT) systems. The proposed model helps in understanding the performance of WPT systems in terms of coil-to-coil efficiency, overall efficiency, and output power capacity and facilitates system performance optimization. Three methods to achieve constant output power for variable-load systems are presented based on system performance analysis. An optimal method can be selected for a specific WPT system by comparing the efficiencies of the three methods calculated with the proposed model. A two-coil 1 kW WPT system is built to verify the proposed mathematical model and constant output power control methods. Experimental results show that when the load resistance varies between 5 and $25{\Omega}$, the system output power can be maintained at 1 kW with a maximum error of 6.75% and an average error of 4%. Coil-to-coil and overall efficiencies can be maintained at above 90% and 85%, respectively, with the selected optimal control method.

• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.277-280
• /
• 2002

With significant development of power electronics technology, the proliferation of nonlinear loads such as static power converters has deteriorated power quality in power transmission and distribution systems. Notably, voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many countries. There are already a lot of PV power generation systems installed in building systems whose harmonics are the worst object for distribution systems as a utility interactive system and also it tends to spread out continuously. In this paper, the authors propose a multy-function inverter control strategy which puts a shunt active filter function to the power inverter of the PV power generation system established on a building system. The effectiveness of the proposed system is demonstrated through the simulation of hypothetical power system using PSCAD/EMTDC.

• Journal of the Korean Society of Systems Engineering
• /
• v.20 no.spc1
• /
• pp.97-107
• /
• 2024

Efforts to respond to climate change are being made in various ways around the world, and in the energy field, continuous research and pilot projects are underway through new and renewable energy, efficient power grid management, and power grid services. Systems are in place to realize these efforts, and the systems created allow for better effectiveness. When implementing a system, systems engineering methodology helps design a more systematic system and can provide verification accuracy and uniformity through intuitive connectivity. In this paper, the original requirements of the power grid stabilization system and the architecture of the system's essential constraints are constructed as a conceptual model and the boundaries and flows between components are defined. By utilizing distributed resources such as EV(Electric Vehicle) and ESS(Energy Storage System) in the power service platform system, we plan to design and build a next-generation power service system that can participate in the power stabilization market and implement a system necessary to respond to climate change in the future.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.530-532
• /
• 2007

This paper presents the design, development and performance of a power conditioning system (PCS) for application to a 250kW Molten Carbonate Fuel Cell (MCFC) generation system. A DSP controller was used to control the dc-dc and dc-ac converter operation for grid connection and power injection to the grid. The controller must also supervise the total PCS operation while communicating with the fuel cell system controller. A control method for parallel operation of dc-dc converters was proposed and verified. A 250kW prototype was successfully built and tested. Experimental performances are compared to minimum target requirements of the PCS for MCFC.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.573-575
• /
• 1994

Resent research activities and technical trends for UPS(UNINTERRUPTIBLE POWER SUPPLY) are reviewed. There are increasing demands for UPS to get mote useful performance. This needs are high-efficiency, high-confidency, high-quality, low-cost. self-diagnosis. maintenance-free, and a wide variety of options. These can be satisfied with high-technology and optimal system coordination. In this paper. according to these demands. a newly developed UPS and a wide variety of options are introduced. Also. the data related are presented.

• International Journal of Control, Automation, and Systems
• /
• v.5 no.5
• /
• pp.526-538
• /
• 2007

This paper presents a neural network based decentralized excitation controller design for large-scale power systems. The proposed controller design considers not only the dynamics of generators but also the algebraic constraints of the power flow equations. The control signals are calculated using only local signals. The transient stability and the coordination of the subsystem control activities are guaranteed through rigorous stability analysis. Neural networks in the controller design are used to approximate the unknown/imprecise dynamics of the local power system and the interconnections. All signals in the closed loop system are guaranteed to be uniformly ultimately bounded. To evaluate its performance, the proposed controller design is compared with conventional controllers optimized using particle swarm optimization. Simulations with a three-machine power system under different disturbances demonstrate the effectiveness of the proposed controller design.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.3
• /
• pp.342-348
• /
• 2013

As a number of wind power generation systems have been installed in power systems in the world, frequency fluctuations due to output power variations from wind farms have become a serious problem. Battery systems have been studied for smoothing the output variations and decreasing the resulting frequency fluctuations. Among these studies, efficient design of battery systems is one of the most important subjects from a point of view of cost. This paper presents a comparative analysis of the smoothing effect between the conventional moving average method and a new method based on frequency response analysis.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.4
• /
• pp.163-171
• /
• 2006

This paper presents a definition of sync phenomenon occurring in power systems, and describes the characteristics of sync in basic electric circuits. In addition, sync observed in basic circuits was extended to the analysis of dynamic characteristics in power systems. This paper, moreover, describes the sync occurring among system outputs from time domain simulation for two-area systems. In power systems, sync is a common phenomenon that is always observed among generator powers or bus voltages. Thus, we can use sync to obtain the characteristics of power systems without being bound to a specific operating point. Sync can be useful information in power system operation and planning.