• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.663-667
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• 2017

Fuel depletion and environmental problems due to the use of fossil fuels have been worsening of late, and the development of alternative energy sources is urgently required to address these problems. Among the alternative energy sources, wind energy is attracting much attention as a clean energy source, because it can be used unlimitedly without any pollutant emissions. In wind power generation, wind energy is converted to kinetic energy through rotor blades and this kinetic energy is converted to electric energy through generators. The design and manufacturing of the blades, which are the major parts of wind power generators, are very important, but South Korea still lacks the requisite basic data and key technologies and, therefore, has to import the blades from overseas. In this study, multi-layered blades capable of generating power at low wind speeds were applied to a small wind power generator and the output characteristics of the generator according to the wind speed and the number of blades were analyzed. As a result, at the maximum wind speed of 8m/s, the application of three blades achieved up to 33% and 18% higher generator output voltage, up to 33% and 15% higher generator output current, and up to 23% and 13% higher generator RPM than the application of one or two blades, respectively. In this study, the application of multi-layered blades to a small wind power generator was shown to improve the output characteristics of the generator and make the collection of electric energy possible even at low wind speeds.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.67-72
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• 2014

Inflow or outflow from the water treatment plant and the sewage water has potential energy. If this potential energy can be converted into electrical energy by water turbine generator, it can help to save energy because of the high capacity utilization. So recently, micro hydro power plant is reviewed in the water treatment facility. If generation capacity is low, induction generator is primarily used. If output capacity is low, generated power is supplied to the inside load. Induction generator can cause voltage drop by the inrush current at a start-up and requires reactive power for magnetization. In this study, we analyzed the flow of power and voltage variation against inrush current that occurs when the induction generator starts under the terms that loads of linear and non-linear of the water purification plant are used. Analysis results are that the voltage drop is within an allowable range and the power factor is slightly reduced by the need of reactive power.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.911-918
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• 2012

Steam generator level control at low power is difficult due to its adverse thermal hydraulic properties, and is usually conducted by an operator. The basic model predictive control (MPC) is similar to the action of an operator in that the operator knows the desired reference trajectory for a finite period of time and takes the necessary control actions needed to ensure the desired trajectory. An MPC is based on a model; the performance as well as the efficiency of the MPC depends heavily on the exactness of the model. In this study, steam generator models that can describe in detail its thermal hydraulic behaviors, particularly at low power, are used in the MPC design. The design scope is divided into two parts. First, the MPC feedwater controller of the feedwater station is determined, and then the MPC level controller for the overall system is designed. Because the dynamic properties of a steam generator change with the power levels, a realistic situation is simulated by changing the transfer functions of the steam generator at every time step. The resulting MPC controller shows good performance.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.749-753
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• 2011

A leisure ship has a stand-alone type power system, and a generator is in use on this condition. But the generator cannot be operated in condition of leisure activity, ocean measurement and etc, because of environment and noise. Recently, renewable energy system is connected with power system of the leisure-ship for saving energy. The renewable energy system can not supply the stable power to leisure-ship because power generation changes according to weather condition. And most of the leisure ship is operated without methodical power management system. This study's purpose is to develop SPMS(Smart Power Management System) algorithm using the renewable energy (photovoltaic, wind power and etc.). The proposed algorithm is able to supply stable the power according to operation mode. Furthermore, the SPMS manages electric load (sailing and communication equipment, TV, fan, etc.) and reduces operating times of the generator. In this paper, the proposed algorithm is realized and executed by using LabVIEW. As a result, the hour for operating the generator is minimized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.277-277
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• 2009

In this paper, PMPG (Piezoelectric Micro Power Generator) was investigated by ANSYS FEA (Finite Element Analysis) to decrease operating frequency and improve out power. The micro power generator was designed to convert ambient vibration energy to electrical power as a ZnO piezoelectric material. To find optimal model in low vibration ambient, the shape of power generator was changed with different membrane width, thickness, length, and proof mass size. Used the ANSYS modal analysis, bending mode and stress distribution of optimal model were analyzed. Also, the displacement with the frequency range was analyzed by harmonic analysis. From the simulation results, the resonance frequency of optimal model is about 373 Hz and confirmed the possibility of ZnO micro power generator for wireless sensor node applications.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.274-277
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• 2008

Pohang Wind Energy Research Center (PoWER-C) is developing a 3 MW Radial Flux Permanent Magnet (RFPM) Synchronous Generator for offshore Wind Energy Converter (WEC). The blade rotor rpm is 15.7 and the gear ratio is set to be 92.93. The nominal generator rpm at the rated load is about 1459. Baseline design with surface mounted PM magnets are completed. However, there is some concern about the excessive eddy current heating in the magnets. To alleviate this problem, another design with embedded magnet is going on. With embedded magnets, the generator length should be increased to compensate the increased flux leakage. But the field fluctuation in the magnets due to the slots are greatly reduced. This means less eddy currents and lower magnet operating temperature. In this report, engineering efforts for embedded rotor is presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.338-342
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• 2014

Energy storage is a key issue when integrating large amounts of intermittent and non-dispatchable renewable energy sources into electric power systems. To maintain the instantaneous power balance and to compensate for the influence of power fluctuations from renewable sources, flexible capability for power control is needed. Adjustable Speed Pumped Storage Power Generator is pumped storage unit that is adjustable for pump output adjustments as well as the highest efficiency operations because it has fast response time. In this paper we address the adjustable speed pumped storage power generator for frequency control against the intermittence of wind turbine output and calculate the appropriate capacity of adjustable speed pumped storage power generator.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.644-647
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• 2007

We have developed electrical power train for 1MW tidal current plant which is composed of both 500kW tidal current plant with doubly-fed induction generator and 500kW tidal current plant with synchronous generator. To check performances of the protype, 2MW dynamometer is used to simulate a helical turbine, and then protype generator and converter are coupled with the dynamometer separately. From the suggested experimental results it is reconfirmed that two kinds of the power train to be installed at the Uldolmok located at southwestern shore in Korea are able to operate under all kinds of the condition about speed and power.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.7
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• pp.329-334
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• 2014

This study indicated the possibility of energy regeneration from waste coolant heat, by using thermoelectric generation integrated with heat pipe. The internal combustion engine rejects more than 60% wasteful energy to the atmosphere by heat. The thermoelectric generator has recently been studied, to convert the energy from engine waste heat into electricity. For coolant waste heat recovery, a thermoelectric generator was investigated, to find out the possibility of vehicular application. Performance characteristics were conducted with various test conditions of coolant temperature, coolant mass flow rate, air temperature, and air velocity, with the thermoelectric generator installed either horizontally or vertically. Experimental results show that the electric power and conversion efficiency increases according to the temperature difference between the hot and cold side of the thermoelectric generator, and the coolant flow rate of the hot side heat exchanger. Performance improvement can be expected by optimizing the heat pipe design.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.485-490
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• 2004

Flywheel Energy Storage System(FESS) consists of a high speed flywheel with an integral motor/generator suspended on non contact bearings and in an evacuated housing. Permanent magnet machines as the FESS motor/generator are a popular choice, since there are no excitation losses which means substantial increase in the efficiency. In this paper, the structural design method of rotor retainer for a high speed motor/generator are presented.