• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.1
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• pp.1-9
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• 1988

This paper descibes a method for the state estimation in power systems with interconnected AC/DC system. The state values in interconnected AC/DC system are estimated using measurement values with the pseudo measurement so that the number of telemetering measurement can be reduced. Especially, the state values in AC system are estimated through hierarchical method after system decomposition including superposition bus was formed for the state estimation in large-scale power systems. The results of the application to the two model power systems show the dffectiveness of the presented algorithms.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.88-98
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• 2011

Development and use of renewable energy due to environmental problems and depletion of energy affect grid-connected power system around the world. Therefore this paper analyzes the characteristic of gird connected photovoltaic power generation system which it is available to connect the utility. Renewable energy photovoltaic power system has been linked to the system to analyze the impact of photovoltaic system. MATLAB / Simulink program is modeled and analyzed on power quality of a photovoltaic power plant. It is measured that power data for the Grid connected photovoltaic power plant with instantaneous measuring, 3sec measuring, 10min measuring for 7 days. Harmonic field measurement have shown that the harmonic contents of a waveform varies with time. A cumulative probability approach is the most commonly used method to solve time varying harmonics. so, it is used 50[%] cumulative probability approach. This paper provides an in depth analysis on power quality field measurement of the Grid connected photovoltaic power plant.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.304-307
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• 1998

High speed railway is under construction from Seoul to Pusan. A traveling train is large single phase load that consumes 14MW power in feeding system of high speed railroad. In this paper, measurement scheme and method of power system harmonics which are generated from those loads in railroad supply system are described. This measurement scheme will be used as a first step to pave a way to power quality management due to harmonic distortion by the highspeed rail way.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.931-938
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• 2002

Combustion dynamics of a dry low NOx gas turbine have been measured by utilizing a dynamic pressure measurement system. The software part of the measurement system, implemented with a commercial general-purpose DASYLab version 5.6 code, basically acquires combustion dynamics signals, performs the FFT analysis, and displays the results. The gas turbine often experiences momentary combustion instability, especially when its combustion mode changes. It is found that the measurement system developed in the study may outperform the other commercial dynamic pressure measurement system. The developed system currently serves to monitor the combustion dynamics of the gas turbine.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.230-236
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• 2002

In real-time power system control, it is essential to measure the power system variables which are voltage, current, real and reactive power, power factor, system frequency and etc. These variables can be estimated or calculated by the synchronized phasor informations of voltage and current. Therefore, the synchronized phasor measurement of voltage and current is very important to real-time power system control. So, we develop SPMD (Synchronized Phasor Measurement Device) for synchronized phasor measurement of voltage and current. In this paper, we present the design and implementation of SPMD for real-time phasor measurement and the test results of developed SPMD on 380 V 3 phase distribution line in laboratory with resistor load and RTDS (Real Time Digital Simulator).

• Journal of Power Electronics
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• v.16 no.3
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• pp.1163-1175
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• 2016

In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.139-141
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• 2005

For the reliable evaluation of the distribution and power transformer no-load loss measurement, measurement uncertainty of the transformer measuring system, consisted of current transformer, potential transformer and power metering equipment is required. In this paper, we describe the uncertainty of transformer measuring system based on ANSI/IEEE C57.12.90.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.451-459
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• 2008

Accurate load modeling is essential for power system static and dynamic analysis. By the nature of the problem of parameter estimation for power system load modeling using actual measurements, multiple local optimal solutions may exist and local methods can be trapped in a local optimal solution giving possibly poor performance. In this paper, Trust-Tech, a novel methodology for global optimization, is applied to tackle the multiple local optimal solutions issue in measurement-based power system load modeling. Multiple sets of parameter values of a composite load model are obtained using Trust-Tech in a deterministic manner. Numerical studies indicate that Trust-Tech along with conventional local methods can be successfully applied to power system load model parameter estimation in measurement-based approaches.

• The Journal of Korea Robotics Society
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• v.5 no.4
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• pp.309-317
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• 2010

This paper proposes an efficient measurement system for the velocity and direction of the wind using the dual rotor wind power generator in vessel. Conventional digital measurement system recognizes the direction and the velocity of the wind using the electric compass or synchronous motor and Vane probe method using hall sensors. But each system has its own short-comings: the synchronous motor has a larger measurement error than the magnetic compass and magnetic compass is weak for the external disturbances such as fluctuation of the vessel. To compensate these short-comings, this paper proposes a new compensation algorithm for the fluctuation errors according to the external interference and the unexpected movement of the vessel along the roll and pitch directions. The proposed system is implemented with the dual compasses and a synchronous motor. The proposed independent power generation system can be operated by itself and can raise the efficiency of the wind power generation systems of 30 ~ 400 W installed along the vertical and horizontal axes. The proposed system also realizes the efficient and reliable power production system by the MPPT algorithm for the real-time recognition of the wind direction and velocity. An advanced switching algorithm for the battery charging system has been also proposed. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.

• Nuclear Engineering and Technology
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• v.45 no.2
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• pp.249-256
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• 2013

In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.