University of the Ryukyus · Faculty of Engineering · 准教授

Research keywords電力系統工学・Surge・Lightning・(connector)

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• A study of lightning location system (Blitz) based on VLF sferics2018 · Blitzortung.org is a worldwide non-commercial low-cost community based Time of Arrival lightning detection and lightning location network. The aim of this project is to accomplish a low budget high accurate worldwide lightning location network based on a high number of receiver sites spaced close to each other, typically separated by 50 km 250km. The stations transmit their data to a central server, where the strike locations are computed by the arrival times of the signals. The station operators are volunteers who bought and assembled the hardware by themselves. We installed this sensor in more than 24 locations throughout Japan, for example Hokkaido, Tokyo, Okinawa, Ogasawara etc. This paper describes the outline of Blitzortung and the evaluation of the position accuracy.
• 鉄塔内部に併設された電力ケーブルに発生するサージ電圧解析のためのEMTPモデルの提案2018 · <p>Surge voltages often have much higher value and changing rate than those of power frequency voltages, and might cause damages to apparatuses or equipment not only on near a surge source, for example lightning struck point, but also on far points from it due to propagating. In addition, surge phenomena often become complex due to the reflections and the superpositions on a point where surge impedances having different value are connected. The surge phenomenon occurring on a power cables connected with a transmission tower is one of these cases. This research's goal is to propose the EMTP model for surge phenomenon occurring on cables arranged through a transmission tower. The proposed model simulates such cable by using a cable model through a pipe conductor. The results calculated by the proposed model ware compared with the results by VSTLrev (Virtual Surge Test Lab. Restructured and Extended Version) which is a surge analysis program based on FDTD (Finite Difference Time Domain) method to verify the accuracy of the proposed model. As a result, the proposed model is reasonable for analysis of a surge phenomenon occurring on a cable through a transmission tower.</p>
• 垂直同軸ケーブルのサージ特性に関する検討2016 · In EMTP, it is very hard to simulate a vertically arranged cable, since its surge impedance gradually changes with the distance from the ground to a top point. In the past, some researches about surge impedances and responses of vertical conductor (for example transmission tower, concrete pole and so on.) have been carried out, these researches are being continued now. However, there is no model of vertical co-axial cable in EMTP. In order to analyze surge voltage arisen on the electrical system, approach of method for treating this model in EMTP is required. In this paper, experiments of surge impedance and response on vertical cable, method of treating for vertical co-axial cable in EMTP and accuracy confirmed as compared result of this model with analysis result of VSTL Rev. (Virtual Surge Test Lab. rev. ) which is constructed under FDTD (Finite Difference Time Domain) method, are reported.
• 建物近傍大地への落雷により発生する屋内配線サージ解析2016 · Household appliances and information equipment with electrical circuits have come into wide use. These appliances and equipment seem sensitive to an electrical surge. In addition, a lightning might affect electrical systems not only on the lightning point but also on the systems at vicinity of the point. If the induced surges invade into low voltage distribution systems, it might cause severe damages to the appliances and the equipment. Therefore, it is necessary to investigate these induced phenomena. FDTD (Finite Difference Time Domain) method is often applied to analyze surge phenomena, which can treat analysis objects as three-dimensional circuits. For simulating these phenomena, we adopt VSTL rev. (Virtual Surge Test Lab. rev.) which is the surge analysis simulation program based on the FDTD method. In this paper, we discuss the investigation results regarding the lightning induced surge phenomena on low voltage distribution lines in a house and the relationship between lightning surges and a soil resistivity, and the effect on the surge phenomena by SPD (Surge Protective Device) on the low voltage distribution lines.

• Voltage Stablity Evaluation in Electric Power System
• 電力系統の最適運用
• Optimal Operation of Electric Power System
• Voltage Stablity Evaluation in Electric Power System

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