The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform
Akiyoshi Tatematsu - One of the best experts on this subject based on the ideXlab platform.
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FDTD-based lightning surge simulation of a Microwave Relay station
2016 33rd International Conference on Lightning Protection (ICLP), 2016Co-Authors: Akiyoshi Tatematsu, Kenichi Yamazaki, Hirokazu MatsumotoAbstract:In electric power systems, Microwave Relay stations are employed to exchange information using electromagnetic radio waves to control the systems. Some Microwave Relay stations are built on tops of mountains, which causes a high incidence of lightning strikes to Microwave towers, and the lightning strikes may result in disturbances of Microwave radio equipment. To protect Microwave radio equipment from lightning, it is required to analyze surge phenomena in Microwave Relay stations and evaluate the effectiveness of lightning protection methodologies. Nowadays, the finite-difference time-domain (FDTD) method to solve Maxwell's equations directly, has been widely and successfully applied to the surge analysis of three-dimensional structures and grounding structures. In this study, setting up a reduced-scale Microwave Relay station model with a Microwave tower of 10 m height, we calculate the distribution of lightning impulse currents in the model and compare the calculated results with measured ones for validation. Secondly, we calculate the magnetic fields inside the Microwave Relay station in the case of direct lightning strikes to the Microwave tower to study the effect of the layout of the Microwave Relay station and the effectiveness of the reinforcing bars used for grounding.
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Overview of the three-dimensional FDTD-based surge simulation code VSTL REV
2016 Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC), 2016Co-Authors: Akiyoshi TatematsuAbstract:The prediction of surge phenomena is required for designing effective lightning protection methodologies, and circuit-theory-based simulation techniques, which assume the transverse electromagnetic (TEM) mode, have traditionally been widely employed for lightning surge analysis. Recently, the finite-difference time-domain (FDTD) method, which is one of the full-wave numerical approaches, has become an effective tool for analyzing surge phenomena in three-dimensional structures and grounding structures thanks to the development of several techniques useful for FDTD-based surge simulations. In this study, we review a three-dimensional FDTD-based surge simulation code developed by CRIEPI, its acceleration using the general-purpose computing on graphics processing units (GPGPU) technique, and its application to surge simulations in a Microwave Relay station.
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Lightning Surge Analysis of a Microwave Relay Station Using the FDTD Method
IEEE Transactions on Electromagnetic Compatibility, 2015Co-Authors: Akiyoshi Tatematsu, Kenichi Yamazaki, Hirokazu MatsumotoAbstract:Microwave Relay stations are key components in controlling power grids and maintaining their stability, but lightning strikes to the stations may cause faults, malfunctions, or even physical damage to Microwave radio equipment. To protect equipment from lightning, it is necessary to predict surge phenomena in a Microwave Relay station, and design effective lightning protection methodologies. Recently, numerical electromagnetic field computation methods to solve Maxwell's equations have entered widespread use for analyzing surge phenomena in 3-D structures such as buildings and towers and in grounding structures such as grounding grids. In this paper, we apply the finite-difference time-domain (FDTD) method to the surge analysis of a Microwave Relay station. First, to validate the applicability of the FDTD method, we set up a reduced-scale model of a Microwave Relay station. Using this model, we measured the distribution of the currents flowing through the station and compared the measured results with those simulated by the FDTD method. Second, through FDTD-based surge simulations, we analyzed the effects of the reinforcing bars of a building, the route of the ground wire of a waveguide, and the layout of a deep earth electrode on the lightning current distribution.
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Applying FDTD Simulation to Lightning Surge Route Analysis in Microwave Relay Stations
Journal of International Council on Electrical Engineering, 2011Co-Authors: Hiroki Kono, Masahiko Fujino, Makoto Yokoyama, Kaname Yonezawa, Yuichi Takahashi, Chiaki Isokawa, Akiyoshi TatematsuAbstract:Microwave multiple radio Relay stations are often built on mountains, and the stations are susceptible to damage from lightning. Therefore, it is important to take adequate lightning protection measures to ensure that communication devices are not damaged by any lightning surge current that penetrates from a lightning rod fitted on such stations. In most cases, the penetration route of the lightning surge current is uncertain, and it is difficult to specifically evaluate the effectiveness of measures against lightning. We calculated the branch aspect of lightning surge current in actual Microwave Relay stations using the finite difference time domain (FDTD) method, which is one way to numerically analyze electromagnetic fields, to directly solve Maxwell's equations. By comparing the calculated results with measured results obtained by injecting a pulse current into a Microwave Relay station, we verified that the current peak value of the calculated results corresponded with the measured results well, both when a steel tower was located on the ground and when it was located on the roof of a Microwave Relay station. We confirmed that the FDTD method can be used to understand the branch current of lightning surges and to study lightning protection measures at Microwave Relay stations.
Zhang Xiao-yan - One of the best experts on this subject based on the ideXlab platform.
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Design of photovoltaic monitoring system based on data mining technique
Chinese Journal of Power Sources, 2013Co-Authors: Zhang Xiao-yanAbstract:Photovoltaic technology is an advanced dynamoelectric technology which can optimize the energy composing.At present,photovoltaic plant system is an important method to supply electricity for lots of farmers in rural area and the Microwave Relay station,For the problem of operation of photovoltaic plant in remote area,it is particularly important to implement remote monitoring of photovoltaic power plants.A photovoltaic monitoring system based on data mining technique was designed.The hardware of the system realized real-time testing by DSP,and the software had various functions,only monitoring the status of system.For a large amount of data of photovoltaic power generation system,it provided the basis for day-to-day management decisions of the photovoltaic power generation using the data mining.
Thomas E. Murphy - One of the best experts on this subject based on the ideXlab platform.
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A Simple, Linearized, Phase-Modulated Analog Optical Transmission System
IEEE Photonics Technology Letters, 2007Co-Authors: Bryan M. Haas, Thomas E. MurphyAbstract:We describe and experimentally demonstrate a new technique to suppress third-order intermodulation distortion (IMD) in a coherent phase-modulated RF optical link. The anisotropic electrooptic coefficient of lithium niobate is exploited to simultaneously modulate orthogonally polarized fields. These fields are then combined to eliminate the third-order distortion. This technique uses a single phase modulator, requiring no external bias or control, for a highly linear photonic Microwave Relay. The resulting suboctave dynamic range is limited by fifth-order IMD instead of third-order IMD
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Suppression of Intermodulation Distortion in Phase-Modulated Analog Photonic Links
2006 International Topical Meeting on Microwave Photonics, 2006Co-Authors: Bryan Haas, Thomas E. MurphyAbstract:We describe and experimentally demonstrate a technique to suppress the dominant in-band analog distortion in an RF photonic link. The anisotropic electrooptic coefficient of lithium niobate is exploited to modulate orthogonally polarized fields. These fields are then combined to null the third-order distortion. This technique uses a single phase modulator, requiring no external bias or control, for a highly linear photonic Microwave Relay. The link is limited by fifth-order intermodulation distortion (IMD) instead of third-order IMD. For many scenarios the added complexity of heterodyne optical detection may be an appropriate cost to gain simplicity at the remote end
Kyoungwhoan Suh - One of the best experts on this subject based on the ideXlab platform.
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a protection ratio related with composite fade margin for detailed frequency coordination of Microwave Relay system networks
ITC-CSCC :International Technical Conference on Circuits Systems Computers and Communications, 2007Co-Authors: Kyoungwhoan SuhAbstract:In this paper, the derivation of protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the Microwave Relay system network. Simulated results for co-channel protection ratio are illustrated over an actual system. The proposed method provides some merits in computing protection ratio in view of an easy extension and practical applications by considering more detailed and various system parameters.
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a protection ratio with composite fade margin for detailed frequency coordination in Microwave Relay system network
Journal of electromagnetic engineering and science, 2007Co-Authors: Kyoungwhoan SuhAbstract:In this paper, the formulation of the protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the Microwave Relay system network, and computed results for co-channel and adjacent channel protection ratios are illustrated over an actual system with 6.2 ㎓. It is shown that the protection ratio to assure a quality of service can be expressed in terms of the composite fade margin, noise-to-interference ratio, net filter discrimination, and system parameters. In addition, the net filter discrimination, depending upon the transmitter spectrum mask and the overall receiver filter characteristic, has been examined to investigate the effect of the adjacent channel protection ratio caused by the adjacent channel interference. Regarding simulated results for 6.2 ㎓, 60 km, 64-QAM, and N/I=6 ㏈ at the bit error rate of 10??, composite fade margin and co-channel protection ratio yield 25.14 and 50.3 ㏈, respectively. Also, the net filter discrimination of 26.5 ㏈ and the adjacent channel protection ratio of 23.8 ㏈ are obtained at the first adjacent channel of 30 ㎒. The proposed method provides some merits in view of a comprehensive and practical application with more detailed and various system parameters needed to access the criteria for making the proper frequency coordination.
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derivation of protection ratio and its calculation for Microwave Relay system based upon composite fade margin and availability
The Journal of Korean Institute of Electromagnetic Engineering and Science, 2007Co-Authors: Kyoungwhoan Suh, Joohwan LeeAbstract:In this paper, the derivation of protection ratio is newly proposed for the detailed planning of frequency coordination in Microwave Relay networks, and computed results for protection ratio of co-channel and adjacent channel are illustrated over the actual system and its frequency. It is shown that the suggested method based upon availability prediction can be expressed in terms of composite fade margin, interference-to-noise ratio(I/N), net filter discrimination, and system parameters. According to results, for 6.7 GHz, 60 km, 64-QAM, and I/N
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a derivation of comprehensive protection ratio and its applications for Microwave Relay system networks
Journal of electromagnetic engineering and science, 2006Co-Authors: Kyoungwhoan SuhAbstract:This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current Microwave frequency band of 6.7 ㎓ including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 ㏈, respectively, for 64-QAM and 60 km at BER 10??. It is shown that the net filter discrimination with 40 ㎒ channel bandwidth provides 28.9 ㏈ at the first adjacent channel, which yields 46.3 ㏈ of adjacent channel protection ratio. In addition, the protection ratio of 38 ㎓ radio Relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.
Hirokazu Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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FDTD-based lightning surge simulation of a Microwave Relay station
2016 33rd International Conference on Lightning Protection (ICLP), 2016Co-Authors: Akiyoshi Tatematsu, Kenichi Yamazaki, Hirokazu MatsumotoAbstract:In electric power systems, Microwave Relay stations are employed to exchange information using electromagnetic radio waves to control the systems. Some Microwave Relay stations are built on tops of mountains, which causes a high incidence of lightning strikes to Microwave towers, and the lightning strikes may result in disturbances of Microwave radio equipment. To protect Microwave radio equipment from lightning, it is required to analyze surge phenomena in Microwave Relay stations and evaluate the effectiveness of lightning protection methodologies. Nowadays, the finite-difference time-domain (FDTD) method to solve Maxwell's equations directly, has been widely and successfully applied to the surge analysis of three-dimensional structures and grounding structures. In this study, setting up a reduced-scale Microwave Relay station model with a Microwave tower of 10 m height, we calculate the distribution of lightning impulse currents in the model and compare the calculated results with measured ones for validation. Secondly, we calculate the magnetic fields inside the Microwave Relay station in the case of direct lightning strikes to the Microwave tower to study the effect of the layout of the Microwave Relay station and the effectiveness of the reinforcing bars used for grounding.
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Lightning Surge Analysis of a Microwave Relay Station Using the FDTD Method
IEEE Transactions on Electromagnetic Compatibility, 2015Co-Authors: Akiyoshi Tatematsu, Kenichi Yamazaki, Hirokazu MatsumotoAbstract:Microwave Relay stations are key components in controlling power grids and maintaining their stability, but lightning strikes to the stations may cause faults, malfunctions, or even physical damage to Microwave radio equipment. To protect equipment from lightning, it is necessary to predict surge phenomena in a Microwave Relay station, and design effective lightning protection methodologies. Recently, numerical electromagnetic field computation methods to solve Maxwell's equations have entered widespread use for analyzing surge phenomena in 3-D structures such as buildings and towers and in grounding structures such as grounding grids. In this paper, we apply the finite-difference time-domain (FDTD) method to the surge analysis of a Microwave Relay station. First, to validate the applicability of the FDTD method, we set up a reduced-scale model of a Microwave Relay station. Using this model, we measured the distribution of the currents flowing through the station and compared the measured results with those simulated by the FDTD method. Second, through FDTD-based surge simulations, we analyzed the effects of the reinforcing bars of a building, the route of the ground wire of a waveguide, and the layout of a deep earth electrode on the lightning current distribution.