• KEPCO Journal on Electric Power and Energy
• /
• 제5권3호
• /
• pp.215-222
• /
• 2019

This work is experimental study of 10 kW specialized Combined Ocean Thermal Energy Conversion. We propose a C-OTEC technology that directly uses exhaust thermal energy from power station condensers to heat the working fluid (R134a), and tests the feasibility of such power station by designing, manufacturing, installing, and operating a 10 kW-pilot facility. Power generation status was monitored by using exhaust thermal energy from an existing power plant located on the east coast of the Korean peninsula, heat exchange with 300 kW of heat capacity, and a turbine, which can exceed enthalpy efficiency of 45%. Output of 8.5 kW at efficiency of 3.5% was monitored when the condenser temperature and seawater temperature are $29^{\circ}C$ and $7.5^{\circ}C$, respectively. The evaluation of the impact of large-capacity C-OTEC technology on power station confirmed the increased value of the technology on existing power generating equipment by improving output value and reducing hot waste water. Through the research result, the technical possibility of C-OTEC has been confirmed, and it is being conducted at 200 kW-class to gain economic feasibility. Based on the results, authors present an empirical study result on the 200 kW C-OTEC design and review the impact on power plant.

• Journal of Power Electronics
• /
• 제19권4호
• /
• pp.1054-1067
• /
• 2019

This paper systematically investigates the influence of device parameters spread on the current distribution of paralleled silicon carbide (SiC) MOSFETs. First, a variation coefficient is introduced and used as the evaluating norm for the parameters spread. Then a sample of 30 SiC MOSFET devices from the same batch of a well-known company is selected and tested under the same conditions as those on datasheet. It is found that there is big difference among parameters spread. Furthermore, comprehensive theoretical and simulation analyses are carried out to study the sensitivity of the current imbalance to variations of the device parameters. Based on the concept of the control variable method, the influence of each device parameter on the steady-state and transient current distributions of paralleled SiC MOSFETs are verified separately by experiments. Finally, some screening suggestions of devices or chips before parallel-connection are provided in terms of different applications and different driver configurations.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.139.2-139.2
• /
• 2011

Compared with a traditional power system of electricity providers, distributed power systems consist of power suppliers which are small and demand-oriented. Each small power supplier tends to utilizes renewable energy sources such as solar and wind power. It is because that home renewable energy systems do not need a large scale infrastructure which is required for traditional power plants. In this work we study an economic feasibility of such a renewable energy source. We describe how renewable power generation works and what it brings in terms of economic benefits. Also, we analyze limitations by the current policy and their possible solutions.

• 환경영향평가
• /
• 제23권1호
• /
• pp.11-17
• /
• 2014

Since the Renewable Portfolio Standard (RPS) would be started in 2012, the use of renewable energy should be 11% of total energy use including bio-fuel in 2030. The economic efficiency for renewable energy in B power plant was considered with the bio-diesel, wind power and solar power. The Net Present Value (NPV) and Benefit/Cost Ratio(BC) were used for the economic efficiency with the cost and benefit analysis. In case of bio-diesel, the cost resulted from the fuel conversion and the benefit would be created with trade and environmental improvement. With regard to wind power and solar power, the construction cost would be required and benefit factors would be same as the bio-diesel. The wind power was the best of economic efficiency of renewable energy as the results of NPV and BC ratio. Whereas, the market of wind power was very popular and the techniques of wind power has been developing rapidly.

• 신재생에너지
• /
• 제20권2호
• /
• pp.65-70
• /
• 2024

The major challenge in promoting large-scale offshore wind power projects is securing local acceptance. Several recent studies have emphasized the crucial role of local governments in addressing this problem. However, local governments have difficulty in achieving clear results because of the lack of expertise and manpower in offshore wind power projects, making thempassive in promoting these initiatives. In this context, we briefly introduce the case of Shinan-gun, which recently successfully conducted a pre-feasibility study on a large-scale offshore wind power complex led by the local government.

• Nuclear Engineering and Technology
• /
• 제56권4호
• /
• pp.1234-1243
• /
• 2024

The pressing need to mitigate greenhouse gas emissions has stimulated a renewed interest in nuclear energy worldwide. However, while numerous countries have shown interest in nuclear power over the course of history, many of them have not continued their pursuit and chosen to defer or abandon their peaceful nuclear power projects. Scrapping a national nuclear power program after making initial efforts implies significant challenges in such a course or a waste of national resources. Therefore, this study aims to identify the crucial factors that influence a country's decision to terminate or hold off its peaceful nuclear power programs. Our empirical analyses demonstrate that major nuclear accidents and leadership changes are significant factors that lead countries to terminate or defer their nuclear power programs. Additionally, we highlight that domestic politics (democracy), lack of military alliance with major nuclear suppliers, low electricity demand, and national energy security environments (energy import, crude oil price) can hamper a country's possibility of regaining interest in a nuclear power program after it has been scrapped, suspended, or deferred. The findings of this study have significant implications for policymakers and stakeholders in the energy sector as they strive to balance the competing demands of energy security, and environmental sustainability.

• 전력전자학회논문지
• /
• 제25권4호
• /
• pp.243-250
• /
• 2020

Energy harvesting is a recent technology involving the harvest and utilization of extremely small surrounding energy. Energy harvesting research is conducted in various fields. Triboelectric nanogenerators (TENGs) are energy harvesting technologies that use static electricity generated by physical movement or friction. Although TENGs generate output power in microwatt levels, they experience high internal impedance compared with other energy harvesting generators, thereby making the continuous transfer of electric power to loads difficult. This study proposes a power management system for TENGs that consists of three stages, that is, an AC/DC rectifier, an impedance coupler switch with a capacitor bank, and a DC/DC converter. In addition, the selection method of the AC/DC rectifier and DC/DC converter is proposed to maximize the amount of power transferred from energy harvesting areas. Furthermore, the impedance coupler switch and capacitor bank are discussed in detail. The validity and performance of the proposed three-stage power management system for TENGs are verified using a prototype system.

• Journal of Power Electronics
• /
• 제8권4호
• /
• pp.291-300
• /
• 2008

In this paper power system and drive-train for omni-directional autonomous mobile robots with multiple energy storage units are presented. Because in proposed system, which is implemented in soccer robots, the ability of power flow control from of multiple separated energy storage units and speed control for each motor are combined, these robots can be derived by more than one power source. This capability, allow robot to diversify its energy source by employing hybrid power sources. In this research Lithium ion polymer batteries have been used for main and auxiliary energy storage units because of their high power and energy densities. And to protect them against deep discharge, over current and short circuit, a protection circuit was designed. The other parts of our robot power system are DC-DC converters and kicker circuit. The simulation and experimental results show proposed scheme and extracted equations are valid and energy management and speed control can be achieved properly using this method. The filed experiments show robot mobility functions to perform the requested motion is enough and it has a high maneuverability in the field.

• 한국태양에너지학회 논문집
• /
• 제31권6호
• /
• pp.23-31
• /
• 2011

The wind energy is one of the most prospective resources in renewable energy. However, the WTGS shouldn't be installed indiscriminately because the power system can be negatively influenced by a variable and uncertain nature of the wind energy. It is the reason why it has to be limited to install the WTGS thoughtlessly mentioned above that support the importance of the maximum penetration limit of wind power. It may required that power system operators suggests a new way of power system operation as percentage of the WTGS increase in the existing power system. The wind power is fixed in a limited area, so using rate of the wind power will be increased by installing additional WTGS. In this paper, we have studied on economic evaluation of the wind capacity increased by restricting the output of the WTGS as the way to increase the wind capacity.

• Journal of Electrical Engineering and Technology
• /
• 제11권2호
• /
• pp.470-479
• /
• 2016

The model based method for energy saving of the separately excited DC motor drive system is proposed in the paper. The accurate power loss model is necessary for this method. Therefore, the adaptive tabu search algorithm is applied to identify the parameters in the power loss model. The field current values for minimum power losses at any load torques and speeds are calculated by the proposed method. The rule based controller is used to control the field current and speed of the motor. The experimental results confirm that the model based method can successfully provide the energy saving for separately excited DC motor drive. The maximum value of the energy saving is 48.61% compared with the conventional drive method.