• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.11
• /
• pp.514-519
• /
• 2006

To improve the mean-life and the reliability of power cable, we have investigated specific heat (Cp) and thermal conductivity of XLPE insulator and semiconducting materials in 154[kV] underground power transmission cable. Specimens were made of sheet form with the seven of specimens for measurement. Specific heat (Cp) and thermal conductivity were measured by DSC (Differential Scanning Calorimetry) and Nano Flash Diffusivity. Specific-heat measurement temperature ranges of XLPE insulator were from $20[^{\circ}C]\;to\;90[^{\circ}C]$, and the heating rate was $1[^{\circ}C/min]$. And the measurement temperatures of thermal conductivity were $25[^{\circ}C],\;55[^{\circ}C]\;and\;90[^{\circ}C]$. In case of semiconducting materials, the measurement temperature ranges of specific heat were from $20[^{\circ}C]\;to\;60[^{\circ}C]$, and the heating rate was $1[^{\circ}C/min]$. And the measurement temperatures of thermal conductivity were $25[^{\circ}C]\;and\;55[^{\circ}]C$. From these experimental results both specific heat and thermal conductivity were increased by heating rate because volume of materials was expanded according to rise in temperature. We could know that a small amount of CNT has a excellent thermal properties.

• 전기의세계
• /
• v.30 no.11
• /
• pp.734-746
• /
• 1981

This paper suggests on-load torque measurement for 3 phase induction motors by input -voltage and current utilizing symmetric coordinate analysis technique on the basis of the induction motor equivalent circuit. In this paper, two cases are treated with, i.e, one is the case where the motors' exciting current and primary leakage impedance voltage drop are compensated automatically, adopting the ideal wattmeter whose current coil impedance and voltage coil impedance are 0 and .inf. respectively, and the other is the case where non-ideal wattmeter is adopted and the compensation above is made by computation. As a result of the case study, following conclusions are obtained. 1) By proper combination of the error propagation law and the limit of power consumption, the desirable overall measurement error of the apparatus can be obtained on the basis of the inherent errors of CT and PT. 2) The measurement error is larger in current simulation circuit than in voltage simulation circuit. 3) Between the two cases, the latter is more advantageous than the former from the viewpoint of feasibility and the measurement error. 4) As the attachment of Ammeter in the current simulation circuit influences the measurement error considerably, its internal impedance should be large considerably. 5) The larger the consumption power of the apparatus is, the easier the feasibility is.

• Journal of Power System Engineering
• /
• v.17 no.5
• /
• pp.121-127
• /
• 2013

In this paper, we propose a distance measurement system for automatic berthing control using a stereo camera mounted on a rotation control device, and a radial pattern target. Automatically controlling the position and attitude of a ship aims to prevent maritime accidents due to human error. Our goal is to measure the relative distance between a ship and an onshore or offshore target for berthing. Therefore, the distance should be continuously measured while tracking a fixed point on a target. To this end, we developed a stereo camerabased distance measurement system that satisfied these requirements. This paper describes the structure and principle of the measurement system. We validate the distance error for target incline due to the relative position and attitude between a camera and a target in miniature scale. In addition, the findings of an experiment in an outdoor environment demonstrate that the proposed measurement system has accuracy within 1 m at a range of 20-100 m which is the acceptable accuracy for automatic berthing.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.5
• /
• pp.902-910
• /
• 2016

This paper presents the overall measurement system for on-line test of super-speed maglev train. The super-speed maglev train is composed of vehicle, propulsion, power, and so on. In order to evaluate and diagnose for sub-system, we made overall measurement system. Just like the other measurement system, it is designed to distributed type. The hardware is consist of SCXI, PXI, Terminal, UPS, and so forth. It is installed on a train, control room, power room and track to collect lots of signals. The software controls hardware system, monitors main data such as inverter current, converter voltage. Using the measurement system, we evaluated a lot of performances for vehicle, track, and so forth. Through the developed system have improved reliability and safety for super-speed maglev train.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.8
• /
• pp.471-480
• /
• 2003

The design of a measurement system to perform Harmonic State Estimation (HSE) is a very complex problem. Among the reasons for its complexity are the system size, conflicting requirements of estimator accuracy, reliability in the presence of transducer noise and data communication failures, adaptability to change in the network topology and cost minimization. In particular, the number of harmonic instruments available is always limited. Therefore, a systematic procedure is needed to design the optimal placement of measurement points. This paper presents a new HSE algorithm which is based on an optimal placement of measurement points using Genetic Algorithms (GAs) which is widely used in areas such as: optimization of the objective function, learning of neural networks, tuning of fuzzy membership functions, machine learning, system identification and control. This HSE has been applied to the Simulation Test Power System for the validation of the new HSE algorithm. The study results have indicated an economical and effective method for optimal placement of measurement points using Genetic Algorithms (GAs) in the Harmonic State Estimation (HSE).

• Journal of Power System Engineering
• /
• v.15 no.5
• /
• pp.91-96
• /
• 2011

The handling ability of containers at the terminal strongly depends on the performance of the cargo handling system such as RTGC(Rubber Tired Gantry Crane) and RMGC(Rail Mounted Gantry Crane). This paper introduces a guide line measurement system on the operating condition, in which two camera are installed to detect the guide line. Because the line tracking is the basic technique for control system design of RTGC, it is necessary to develop a useful and reliable measurement system. If the displacement and angle of the RTGC relative to a guide line as the trajectory to follow is obtained, the position of RTGC is automatically calculated. Therefore, in this paper, a camera-based measurement system is introduced. The proposed measurement system is robust against light fluctuation and cracks of the guide line. This system consists of two camera and a PC which are installed at the lower side of the RTGC. Two edges of the guide line are detected from an input image taken by the cameras in the moving state, and these positions are determined in a Hough parameter space by using the Hough transformation method. From the experimental results, the accuracy and usefulness of the proposed system is evaluated by comparing other instruments.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.4
• /
• pp.400-410
• /
• 2008

Reduction of structure-borne noise in the compartment of a car is an important task in automotive engineering. Many methods which analyze noise transfer path have been generally used for structure-borne noise. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation for each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow measurement has been used for a simple isolation system or a laboratory based isolation system. This paper identifies the transfer path of booming noise in a SUV. The powertrain used for test has a in-line 4cylinder engine and 5-shift auto-transmission. This powertrain is transversely supported by four isolators. We calculated the energy flow throughout four isolator by the measurement of power flow and the contribution of energy flow at each isolator.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.996-1006
• /
• 2017

Phasor Measurement Unit (PMU) placement is a crucial problem for State Estimation (SE) of the power system, which can ensure that the power network is fully observed. Further, the observation reliability problem of the system has been concerned in the operation conditions. In this paper, based on modified weighted adjacent matrix ($A_w$), an optimal placement method is proposed to solve simultaneously two problems involving the optimal PMU placement problem and the observation reliability enhancement problem of the system. The purpose of the proposed method is to achieve both the minimum total cost and the maximum observation reliability, with a focus on increasing the security of observability, strengthening the observation reliability of buses as well as enhancing the effectiveness of redundancy. Simulations on IEEE 14, 24, 30 and 57 bus test systems are presented to justify the methodology. The results of this study show that the proposed method is not only ensuring the power network having the observability effectively but also enhancing significantly the observation reliability. Therefore, it can be a useful tool for SE of the power system.

• Nuclear Engineering and Technology
• /
• v.54 no.3
• /
• pp.781-789
• /
• 2022

KHNP had licensed Dynamic Control rod Reactivity Measurement (DCRM) method using detector current signals of PWRs in 2006. The method has been applied to all PWRs in Korea for about 15 years successfully. However, the original method was inapplicable to PWRs using low-sensitivity integral fission chamber as ex-core detectors because of their pulse pile-up and the nonlinearity of the mean-square voltage at low power region. Therefore, to overcome this disadvantage, a modified method, DCRM-EK, was developed using kinetics behavior after equilibrium condition where the pulse counts maintain the maximum value before pulse pile-up. Overall measurement, analysis procedure, and related computer codes were changed slightly to reflect the site test condition. The new method was applied to a total of 15 control rods of 1000 MWe and 1400 MWe PWRs in Korea with worths in the range of 200 pcm -1200 pcm. The results show the average difference of -0.4% and the maximum difference of 7.1% compared to the design values. Therefore, the new DCRM-EK will be applied to PWRs using low sensitivity integral fission chambers, and also can replace the original DCRM when the evaluation fails by big noises present in current or voltage signals of uncompensated/compensated ion chambers.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2268-2277
• /
• 2017

As constantly increasing wind power penetrates power grid, wind power plants (WPPs) are exerting a direct influence on the traditional power system. Most of WPPs are using variable speed constant frequency (VSCF) wind turbines equipped with doubly fed induction generators (DFIGs) due to their high efficiency over other wind turbine generators (WTGs). Therefore, the analysis of DFIG has attracted considerable attention. Precisely measuring optimum reference speed is basis of utilized maximum wind power in electric power generation. If the measurement of wind speed can be easily taken, the reference of rotation speed can be easily calculated by known system's parameters. However, considering the varying wind speed at different locations of blade, the turbulence and tower shadow also increase the difficulty of its measurement. The aim of this study is to design fuzzy controllers to replace the wind speedometer to track the optimum generator speed based on the errors of generator output power and rotation speed in varying wind speed. Besides, this paper proposes the fuzzy adaptive PID control to replace traditional PID control under rated wind speed in variable-pitch wind turbine, which can detect and analyze important aspects, such as unforeseeable conditions, parameters delay and interference in the control process, and conducts online optimal adjustment of PID parameters to fulfill the requirement of variable pitch control system.