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针对目前输电线路施工缺乏吊臂机械结构与输电线路电气安全距离的实时监测手段,施工过程中靠看护人员肉眼难以准确识别安全距离的问题,研究输电线路识别测距和预警相关技术,解决输电线路防机械碰线实时监测手段缺失的问题。提出了以电场感应、回波反射、视觉识别等多物理量传感为手段,多传感数据同步测量、互为补充,建立了顾及运动状态参数及抗差估计思想的滤波解算方法,根据机械运动状态估计量,实时预测距离变化趋势。解决了输电线路导线目标小、周围电磁环境复杂、测量传感器与输电线相对运动引起的导线难以识别和测量的难题,实现了机械吊臂与输电线路安全距离的精确测量。 相似文献
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目前提出的高海拔直流输电线路损耗检测方法对电晕损耗的预测能力较弱.针对现有问题,引入电晕预测技术,提出了一种新的高海拔直流输电线路损耗检测方法.确定高海拔直流输电线路电压变化规律,分析不同结构参数下的输电线路海拔高度和线路间距,进而计算输电线路表面最大电场强度.确定电压参数后,针对高海拔地区特点,提出输电线路损耗检测公... 相似文献
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为了提高智能化光纤复合架空线路态势感知的实时性,将人工神经网络方法应用于光纤沿线应变解调,确定了神经网络的结构。编程实现了基于洛伦兹模型的最小二乘谱拟合方法和神经网络方法,采用不同信噪比和布里渊频移的布里渊谱训练神经网络,将它们应用于某光纤复合架空线路沿线光纤应变的测量,从不同角度比较了两种方法的计算结果。计算结果表明,神经网络方法能有效获得光纤沿线的布里渊频移进而获得应变,具有与谱拟合方法相似的准确性,但应变解调时间仅约为谱拟合方法的1/20000。研究结果为提高智能光纤复合架空线路态势感知的实时性提供了参考。 相似文献
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利用无人机进行输电线路巡检是近几年国内外研究的热点技术之一,其优点是在无需拉闸断电的情况下,即可对输电线路进行检测,对其故障进行判别。根据输电线路设备的特征,应用图像处理与模式识别技术,提出了一种识别绝缘子、防震锤和输电塔的方法。该方法先采用中值滤波、膨胀和腐蚀等方法对灰度化后的航拍图像进行预处理,然后提取预处理后图像的小波特征值,最后采用AP(Affinity Propagation)聚类方法对目标图像进行分类与识别。实验结果表明,所提出的方法能够有效的识别绝缘子、防震锤和输电塔等目标,具有较好的鲁棒性和准确性。 相似文献
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输电线路雷击故障的准确识别对于防雷设计的改进及线路安全运行具有重要的意义,但输电线路故障时的电流信号为典型的非平稳信号,且电流信号的采集还存在众多的干扰。针对输电线路雷击故障识别困难的现状,将具有良好局部时频性能的小波多尺度变换应用于输电线路雷击故障识别中,通过对故障暂态电流的小波多尺度变换提取出波形畸变率和尺度6与尺度1细节系数能量比值,并以这两个特征量作为故障识别的判据,通过不同噪声干扰强度下的故障识别对比分析验证了文中方法的有效性和优越性。 相似文献
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In a standard Schiffman phase shifter a coupled section and a uniform transmission line are used to give a differential phase shift. In order to achieve larger bandwidth it is necessary to use tight coupled sections which are difficult to realize. It is shown how different configurations of coupled lines or parallel connected coupled lines can be used together with a uniform transmission line, other coupled lines, or parallel connected coupled lines in order to obtain a differential phase shifter with loose coupled lines and the same performance as for the standard case. The measurements confirm the calculated results, leading to a more realizable structure 相似文献
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非平行微带线是印刷电路板(PCB)上不可避免的互连结构。针对PCB 上非平行微带线间的串扰问题,用平行微带线近似非平行微带线,把平行耦合微带线间的串扰抵消方法应用到非平行耦合微带线中,提出了利用耦合传输线信道传输矩阵方法来进行远端串扰抵消,在对非平行耦合传输线信道传输矩阵进行特征值分解的基础上构建串扰抵消电路。仿真了非平行微带线间夹角分别为q=3°、5°、10°时的串扰,结果表明,该方法可以有效改善非平行微带线上信号眼图的质量,串扰抵消效果良好。 相似文献
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Seong-Sik Myoung Yongshik Lee Jong-Gwan Yook 《Microwave Theory and Techniques》2007,55(7):1531-1538
This paper proposes a bandwidth-compensation method for miniaturized filters based on short-ended parallel coupled lines. Capacitive loading of such coupled lines is a relatively simple means of reducing the line lengths. In this study, a method is developed that predicts exactly the degree of reduction in the fractional bandwidth due to miniaturization. Using this method, the fractional bandwidth of the prototype coupled line filter can be adjusted, enabling miniaturized filters to maintain the targeted fractional bandwidth. The proposed bandwidth-compensation method applies for any type of filters with coupled lines realized with various transmission lines, with uniform or nonuniform line lengths. Experimental results are also presented that verify the validity of the method. 相似文献
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We have developed an accurate method for measuring the complex propagation constant and characteristic impedance of transmission lines embedded in multilayer printed circuit boards. It is based on mathematical error-removal schemes using two different length transmission lines and an advanced via-hole structure that minimizes coupling. Consequently, associated errors, due to discontinuities and interference can be effectively eliminated, and the frequency dependencies of the transmission line parameters can be clarified in wide frequency bandwidths. We verified the validity of this method in frequency ranges up to at least 18 GHz, by comparing the determined values with the theory derived from transverse electromagnetic (TEM) approximations. 相似文献
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《Microwave Theory and Techniques》2005,53(8):2587-2593
This paper proposes a new structure for a tunable impedance transformer. The proposed transformer consists of a quarter-wavelength transmission line with variable characteristic impedance. The operating principle of the variable characteristic impedance is based on the use of parallel combinations of multiple transmission lines and by controlling the line connection with RF switches. Multiple switches are inserted at the in/out terminals of each transmission line. Since a parallel microstrip transmission line has a unique structure that involves a partially removed ground plane under the conductor line, it is possible to realize a high characteristic impedance line with a wide linewidth. 相似文献
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A current decomposition method is proposed for the analysis of field coupling to mass wires near complex structures. The foremost attribute of the method is the decomposition of the current on each wire into push-pull and push-push mode currents. The former refers to the perturbation current accounting for the interactions among the wires within the bundle, whereas the latter represents the interactions between the mass wire bundle and the surrounding structure. Multiconductor transmission line theory is employed to compute the push-pull mode current by using one of the wires in the bundle as the return/reference conductor. Current induced on a test wire located along the reference line is used to compute the push-push mode. For this analysis, we employed the method of moments for the electromagnetic analysis of surrounding structure and simulation program with integrated circuit emphasis (SPICE)-like simulators for the analysis of a circuit model of the transmission lines extracted via the partial element equivalent circuit method. Several validation examples (including transmission lines inside an automobile) are presented. It is also shown that the traditional transmission line theory based on quasi-static analysis fails with increasing complexity of the surrounding structure. 相似文献
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提出了一种用传输线在微带交叉滤波器和腔体交叉滤波器中实现交叉耦合极性改变的新方法。在微带交叉耦合滤波器中运用180°电长度的传输线实现源与非相邻谐振器的耦合,可使交叉耦合极性由容性变为感性。在腔体交叉耦合滤波器中,使用180°左右电长度的传输线,可使传输零点从阻带高端移动到阻带低端。讨论了不同电长度的传输线对交叉耦合的影响,通过调节传输线的电长度,控制传输零点的位置,提高滤波器的带外抑制。这种改变耦合极性的方法,可以用同一耦合方式获得任意位置的传输零点,给滤波器设计提供了更大的自由度。 相似文献
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为准确检测遥感图像中机场跑道区域,提出一种基于长线状特征的跑道识别方法。利用跑道在图像中的高对比度和整体的长直线特征,提取出潜在的跑道中心线。沿中心线各线点的法向扩展出有效边缘,并去除其中的小连通区域。对有效边缘进行Hough变换,提取满足机场约束条件的平行直线对。针对跑道建设标准中两端入口标志的高灰度值特点,沿提取所得平行线对的法向进行投影并搜索求出跑道两端。在混凝土跑道和沥青跑道上的检测效果表明,此方法能够有效去除复杂背景且具有较高的检测准确性。 相似文献
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随着多导体传输线内各导体之间间距的减小, 导体之间的近邻效应对传输线的分布参数和传输特性的影响越来越大.为此, 我们针对三种典型的传输线结构, 分别建立了基于矢势有限元方法分析的多导体传输线的模型, 并分析了近邻效应对磁通密度和分布电感的影响.利用提出的方法计算了同轴传输线的单位长度分布电感, 并将它与采用解析方法得到的结果进行比较来证明该方法的正确性.计算双线传输线在不同间距时的单位长度电感, 与理论分析得到的结果相比较验证了导线间距越小, 近邻效应对单位长度电感的影响越大.最后, 计算考虑了近邻效应的耦合微带线的电感矩阵, 并将它与其他不考虑近邻效应的方法得到的结果相比较, 说明近邻效应对传输线电感矩阵的影响. 相似文献