• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.162-168
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• 2009

This thesis is based on the research and experiment of the optimal efficiency generation of electric power. The research and experiment were conducted to search the optimal generation of electric power from a specific amount of solar energy from Photovoltaic Power System with a solar position tracker were used. The changes in the array angles and spacing of the PV Module were also taken into account as well. Here are the findings and the conclusions. First of all, based on experiment using the various anglers, the efficiency generation of electric power increased to a maximum of approximately $12{\sim}17$[%] more at the PV module inclination angle of 30[$^{\circ}$] than at the inclination angles of 20[$^{\circ}$] and 40[$^{\circ}$]. As a result, we have found that installing the PV module inclination at the angle of 30[$^{\circ}$] brought about the most efficient conversion effect of the Photovoltaic Power System. But, when the solar cell is installed on a roof or rooftop where snow builds up, it is the most appropriate to install the solar energy at an 35[$^{\circ}$] angle so that snow slides down and not build up on the module.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1518-1526
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• 2015

For now, there are some low frequency oscillations in the power system which feature low frequency oscillation with positive damping and cannot be explained by traditional low frequency oscillation mechanisms. Concerning this issue, the dynamic damping effect is put forward on the basis of the power-angle curve and the study of damping torque in this article. That is, in the process of oscillation, damping will dynamically change and will be less than that of the stable operating point especially when the angle of the stable operating point and the oscillation amplitude are large. In a situation with weak damping, the damping may turn negative when the oscillation amplitude increases to a certain extent, which may result in an amplitude-increasing oscillation. Finally, the simulation of the two-machine two-area system verifies the arguments in this paper which may provide new ideas for the analysis and control of some unclear low frequency phenomena.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.511-518
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• 2005

This paper presents the design and drive characteristics of a switched reluctance motor for an electric power pallet vehicle. The designed switched reluctance motor is redesigned by using the finite element analysis(FEA) as a variation of the pole-arc angle for the purpose of an electric power pallet vehicle performance. The output power and torque characteristics of a switched reluctance motor are variable by switching angles of the commutator. Therefor this paper is studied about relationship between the output power and torque characteristics of a switched reluctance motor according to switching angles. The output power of the characteristic point of an electric power pallet vehicle has been shown by experiment. The designed motor drive system operates with the low voltage and high current with using the battery. The core and frame temperatures were described. In this paper, the designed motor is shown better drive characteristics than the DC motor from the rated to maximum, which is verified by the finite element analysis and experimental results.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.317-321
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• 2021

As the large-scale renewable energy power plant increases, the high-capacity and compact Energy Storage System (ESS) is required. However, this trend could reduce the insulation reliability of ESS. In this study, the surface flashover characteristics for four types of solid insulators are investigated in the uniform electric field with AC and Lightning Impulse (LI) voltage waveforms under various contamination levels. In addtion, insulator surfaces are compared based on the contact angle before and after surface flashover. The experimental results show that AC flashover voltage is dependent on the materials and the contamination level, but LI flashover voltage is only associated with the contamination level. Especially, AC flashover voltage of PC (PolyCarbonate) is higher than that of other insulators, which is associated with the unique and sequential creepage discharge propagation pattern of PC. The localized discharges on the surface of PC form corresponding tracking points. Then, the interconnected trackings result in the complete flashover. This flashover patterns degrade the surface of PC much more than that of epoxy and Bulk Molding Compoud (BMC). Thus, the contact angle of PC is significantly reduced compared to that of other insulators. The increased hydrophilicity in the surface of PC enhances the insulator surface conductivity.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.299-301
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• 2008

For an efficient operation of today's power system, power engineers are required to analyze enormous amount of data. Owing to the development of technology, a variety of power systems computational tools have been developed and commercialized. However, the practical use of computational tools not only requires that people be able to understand the results the tools produce but also extract the required information from the simulation results which generally involves massive amount of information. This paper introduces a novel interface that would complement the drawbacks in the visualization of data of the pre-existing tools and assist the user in readily retrieving the required information, in this case the rotor angle data, of the simulated system thereby making power system analysis more feasible to be effectuated.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.6-12
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• 2012

We present the optical models and calculation results of thin-film organic solar cells (OSCs) at oblique incidence of light, using the transfer matrix method. The simple expression for the optical power dissipation is derived at oblique incidence for s- and p-polarized light. The spatial distribution of the electric field intensity, the optical power density, and the optical power dissipation are calculated in both s- and p-polarized light with respect to the incidence angle. We identify how the light absorption efficiency for p-polarized light becomes relatively larger than that for s-polarized light as the incidence angle increases.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.704-711
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• 1999

This paper presents a design of fuzzy power system stabilizer (FPSS) using adaptive evolutionary computation (AEC). We have proposed an adaptive evolutionary algorithm which uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations. FPSS shows better control performances than conventional power system stabilizer (CPSS) in three-phase fault with heavy load which is used when tuning FPSS. To show the robustness of the proposed FPSS, it is appliedto damp the low frequency oscillations caused by disturbances such as three-phase fault with normal and light load, the angle deviation of generator with normal and light load and the angle deviation of generator with heavy load. Proposed FPSS shows better robustness than CPSS.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.313-315
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• 2002

Frequency and phasor are the most important quantities in power system operation because they can reflect the whole power system situation. This paper proposes a design and implementation using phase angle difference calculation for frequency measuring in power system. The process is considered to be complicated as compared to the present proposed method. Performance test results, using signals from Excel program, indicate that the proposed technique can provide accurate estimates within 16ms.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.73-80
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• 2009

A tidal current turbine is designed and analyzed numerically by using blade element momentum theory. The rated power has a limitation because the diameter of the tidal current turbine cannot exceed the depth of sea water. This study investigates a horizontal axis tidal-current turbine with a rated power of 500 kW. NACA-6 series laminar foil shape is used for basic airfoil along the blade span. The distributions of chord length and twist angle along the blade span are obtained from the hydrodynamic optimization procedure. Prandtl's tip loss correction and angle of attack correction considering the three-dimensional effect are applied for this study. The power coefficient curve shows maximum peak at the rated tip speed ratio of 6.0, and the maximum torque coefficient is developed at the tip speed ratio of 4. The drag coefficient reaches about 0.85 at the design tip speed ratio.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2358-2360
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• 1999

This study describes the reliability assessment of 3 years-aged polymer insulators using polymer characterization techniques such as SEM, contact angle, DSC, FTIR. Two kinds of polymer insulators were dismounted from 5 fields. All polymer insulators showed the micro-cracks and the reduction of characteristic peaks on the shed surface. Contact angle was increased with time. Although some superficial changes have occurred, there are no significant changes in various properties. Comparison of dismounted insulators to new ones revealed that the field-aged insulators are reliable for the present.