• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.389-391
• /
• 2005

This paper describes experimental analysis of UPFC, which is composed of cascaded H-bridge modules and single-phase multi-winding transformers for isolation. The operational characteristic was analyzed through experimental works with a scaled model, and simulation results with PSCAD/EMTDC. The UPFC proposed In this paper can be directly connected to the transmission line without series injection transformers. It has flexibility to expand the operation voltage by increasing the number of H-bridge modules. The analysis results can be utilized to design the actual UPFC system applicable for the transmission system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.2
• /
• pp.253-256
• /
• 2016

In this paper, the power system with electric vehicles is analyzed considering the mobility and diffusion rate of electric vehicles in the smart grid environment. In the previous studies, load modeling and load composition rates have been researched and the results are applied to develop a new load model to explain the mobility of electric vehicles which could affect on the power system status such as power flow and stability. The results would be utilized to research and develop power system analysis methods considering movable charging characteristics of electric vehicles including movable discharging characteristics which could be affected by the diffusion progress of electric vehicles.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.3
• /
• pp.312-319
• /
• 2007

The solution of the power flow is one of the most important problems in electrical power systems. These traditional methods such as Gauss-Seidel method and Newton-Raphson (NR) method have had drawbacks up to now such as initial values, abnormal operating solutions and divergences in heavy loads. In order to overcome theses problems, the power flow solution incorporating genetic algorithm (GA) is introduced in this paper. General operator of genetic algorithm, arithmetic crossover, and non-uniform mutation operator of GA are suggested to solve the power flow problem. While abnormal solution cannot be obtained by a NR method, multiple power flow solution can be obtained by a GA method. With a heavy load, both normal solution and abnormal solution can be obtained by a proposed method. In this paper, a floating number representation instead of the binary number representation is introduced for accuracy. Simulation results have been compared with traditional methods.

• Nuclear Engineering and Technology
• /
• v.53 no.12
• /
• pp.3910-3917
• /
• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.93-102
• /
• 2021

The analysis of the fluid flow characteristics in reactor pressure vessel is an important part of the hydraulic design of nuclear power plant, which is related to the structure design of reactor internals, the flow distribution at core inlet and the safety of nuclear power plant. The flow distribution and mixing characteristics in the pressurized reactor vessel for the 1000MWe advanced pressurized water reactor is analyzed by using Computational Fluid Dynamics (CFD) method in this study. The geometry model of the full-scaled reactor vessel is built, which includes the cold and hot legs, downcomer, lower plenum, core, upper plenum, top plenum, and is verified with some parameters in DCD. Under normal condition, it is found that the flow skirt, core plate holes and outlet pipe cause pressure loss. The maximum and minimum flow coefficient is 1.028 and 0.961 respectively, and the standard deviation is 0.019. Compared with other reactor type, it shows relatively uniform of the flow distribution at the core inlet. The coolant mixing coefficient is investigated with adding additional variables, showing that mass transfer of coolant occurs near the interface. The coolant mainly distributes in the 90° area of the corresponding core inlet, and mixes at the interface with the coolant from the adjacent cold leg. 0.1% of corresponding coolant is still distributed at the inlet of the outer-ring components, indicating wide range of mixing coefficient distribution.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1296-1298
• /
• 1999

This paper describes a power flow method for the unified power flow controller(UPFC) considering equipment sizes and constraints. The operation of UPFC subject to the practical constraints encounted in an actual high power installation. So the Power flow method for FACTS must be considered its constraints for power system analysis. The proposed UPFC power flow method was implemented by PSS/E and IPLAN.

• KIEE International Transactions on Power Engineering
• /
• v.4A no.2
• /
• pp.73-78
• /
• 2004

This paper proposes a framework for determining the minimum load shedding for restoring solvability. The framework includes a continuation power flow (CPF) and an optimal power flow (OPF). The CPF parameterizes a specified outage from a set of multiple contingencies causing unsolvable cases, and it traces the path of solutions with respect to the parameter variation. At the nose point of the path, sensitivity analysis is performed in order to achieve the most effective control location for load shedding. Using the control location information, the OPF for locating the minimum load shedding is executed in order to restore power flow solvability. It is highlighted that the framework systematically determines control locations and the proper amount of load shedding. In a numerical simulation, an illustrative example of the proposed framework is shown by applying it to the New England 39 bus system.

• Particle and aerosol research
• /
• v.12 no.1
• /
• pp.21-26
• /
• 2016

In order to realize In-line and convenient measurement for solid-gas two phase flows, Light Transmission Fluctuation (LTF) based on the random variation of transmitted light intensity, light scattering theory and cross-correlation method was presented for online measurement of particle size, concentration and velocity. The statistical relationship among transmitted light intensity, particle size and particle number in measurement zone was described by Beer-Lambert Law. Accordingly, the particle size and concentration were determined from the fluctuation signal of transmitted light intensity. Simultaneously, the particle velocity was calculated by cross-correlation analysis of two neighboring light beams. By considering the influence of concentration variation in industrial applications, the improved algorithm based on spectral analysis of transmitted light intensity was proposed to improve measurement accuracy and stability. Therefore, the online measurement system based on LTF was developed and applied to measure pulverized coal in power station and raw material in cement plant. The particle size, concentration and velocity of powder were monitored in real-time. It can provide important references for optimal control, energy saving and emission reduction of energy-intensive industries.

• Journal of the Korea Computer Industry Society
• /
• v.4 no.10
• /
• pp.611-620
• /
• 2003

This paper presents improved GUI based analysis tool o( load flow of power system (or contingency. It is effective tool to facilitate the teaching and learning of load flow of power system. This software is the named of PFGUI(Power Flow GUI) that written in TooIBookII of Asymetrix. The PFGUI is friendly for study for power system operation and control because picture provide a better visualizing of relationships between input parameters and effects than a tabula type result. This PFGUI enables topology and the output data of load flow for line outages to be shown on same picture page. Users can input the system data for power flow on the the picture and can easily see the the result diagram of bus voltage, bus power, line flow. It is also observe the effects of different types of variation of tap, shunt capacitor, loads level, line outages. Proposed PFGUI has been studied on the Ward-Hale 6-Bus system.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.5
• /
• pp.87-95
• /
• 2000

The numerical analysis and the experiments are carried out to develop the design program for the flow control valve attached to the vane pump for power steering. The factors affecting the flow rate characteristics are analyzed by the experiments and the numerical analysis. The results are summarized as follows; (1) the main factors affecting to the first and second control flow rate are the diameter of big and small rod of the spool. (2) the cut off is mainly affected by the main spring constant, the initial displacement of main spring and the small diameter of the spool. (3) the dropping slope characteristics are decided by the chamfer of spool and the dynamic characteristics of the spool.