共查询到20条相似文献，搜索用时 15 毫秒
1.
Long span ultra-high voltage （UHV） transmission lines have serious aeolian vibration problems. To control these vibrations, we improved the energy balance method in the following aspects： the wind power input, the conductor self-damping, and the damper dissipated power. Meanwhile, we built a theoretical mechanical model of β wire dampers and derived energy dissipation calculation formulae. This permits the vibration energy dissipated by β wire dampers can be considered in the energy balance method. Then, we developed a computer program based on the improved energy balance method using Matlab, and analyzed UHV long span ground wires of the Han River long span project in P. R. China. The results show that the combination of β wire dampers and Stockbridge dampers can reduce vibration of UHV long span transmission lines, which provides a reference for research and construction of UHV engineering projects. 相似文献
2.
The conventional fault analysis method based on symmetrical components supposes that the three-phase parameters of un-transposed transmission line are symmetrical in case of fault. The errors caused by the method with the symmetrical distributed parameter circuit model as the equivalent circuit of the un-transposed ultra high voltage (UHV) transmission line were studied under both normal operation and fault, and the corresponding problems arising were pointed out. By contrast with electromagnetic transient and power electronics (EMTPE) simulation results with the asymmetrical distributed parameter circuit model of un-transposed line, it is shown that the conventional method cannot show the existence of negative and zero sequences before fault happening and there are many errors on voltage and current after fault happening which are different with fault types. The error ranges of voltage and current are 2.13%-81.13% and -7.82%-86.15%, respectively. 相似文献
3.
Huang Jing-yun Ye Zhi-zhen Lu Huan-ming Zhao Bing-hui Wang Lei Que Duan-lin 《浙江大学学报(A卷英文版)》2000,1(4):427-430
An ultrahigh vacuum chemical vapor deposition (UHV/CVD) system with reflection high energy electron diffraction (RHEED) was
introduced. The Si epilayers and SiGe strained-layers on three-inch Si (100) substrates were grown in this UHV/CVD system.
The substrate temperature during growth was from 550°C to 780°C. The properties of epilayers were characterized by high-resolution
cross-sectional transmission electron microscopy (TEM), double crystal X-ray diffraction (DCXRD), and spreading resistance
(SPR). A B-doped SiGe epilayer with uniform resistivity distribution was grown.
Project supported by NSFC and Science Commission Program of Zhejiang Province of China. 相似文献
4.
王印峰 《河北能源职业技术学院学报》2014,(2):70-71
随着社会经济发展,高压电网的规模不断扩大,高压架空线路遭受雷击的现象时有发生,高压架空线路防雷保护十分必要。本文针对山区地形雷电侵害特点及危害,根据多年架空供电线路维护经验,介绍了两种山区地形高压架空线路的防雷保护措施。 相似文献
5.
6.
提出以计算机网络为基础的超高压输电线路的故障定位和录波系统，在结构上具有开放式的特点，可根据要求方便地接入扩建线路，并且高速网络数通讯使系统具有极好的实时性．文中重点论述了故障定位新方法，它不仅在线路故障定碍位的数学模型建立上考虑了超高压长距离线路的分布参数特性，并且在计算方法上计及故障线路两端故障电流的相位，经ＥＭＴＰ仿真及测试可证明所提出的综合方法对超高运长距离输电线路故障定位的精确性．论述了以计算机网络为基础的输电线故障定位和录波系统，给出了系统结构和主要特点，重点阐述了所提出的精确超高压长距离输电线故障定位的新方法。 相似文献
7.
针对常规推挽变换器中变压器的漏感会在开关管两端产生电压尖峰的问题,有源钳位推挽变换器可以有效地对此现象进行抑制。本文对推挽变换器的数学模型进行分析,使用二阶工程设计法整定有源钳位推挽变换器中的电压负反馈PI调节的参数值,并且通过仿真与实验的验证,确保有源钳位推挽变换器可以稳定高效地运行,同时消除了由变压器漏感引起的开关管两端电压尖峰。 相似文献
8.
9.
在电力数据采集终端中滤波器常用来滤除耦合在电力信号传输线路上的高频谐波、抑制干扰,以确保有效地采集电力线上的电压和电流信号,提高系统的采样精度．本文提出一种新的混合滤波方案,即采用二阶压控电压源低通滤波电路的硬件滤波和去极值平均魔波与维纳滤波相结合的数字滤波方案,采用硬件滤波滤除采集信号中的高频分量,通过软件滤波抑制低频分量中的干扰．实验结果表明,这种方案可行且能达到预期的效果． 相似文献
10.
该文对摩尔根电路作了一些改进,即滤波器的体积应尽可能小,以便电路迅速响应,在提高电路的灵敏度的同时,效率依然可保持很高。其次,列举了对小型滤波器试验进行分析所得出的数据。第三,这些分析表明,若一个电流可饱和换流器(SCT)设计适当的话,电路就可表现为一个自调节的恒压源。最后,给出了一个实例,即由某些简单的电路元件组成保护电路,可防止滤波器故障而导致负荷过电流和过电压。 相似文献
11.
为了解决我国西南山区高压输电线路覆冰问题,在总结和分析国内外现有除冰技术基础上,以强力除冰、有效防冰为目标,提出“除冰为主,除防结合”的新型除冰、防冰理念。应用模块化设计,对机器人整体架构、本体机构、除冰机构、防冻喷涂机构以及控制系统进行详细设计说明,对机器人关键零部件进行有限元分析。结果显示,该除冰方案结构设计合理,适用于西南地区高压线缆除冰、防冰工作。该机器人具有结构紧凑、重量轻、简单高效、实用性强等特点,为输电线路除冰、防冻提供了一种新思路,具有较好的社会效益和应用前景。 相似文献
12.
直流绝缘子串电位分布影响因素 总被引：3，自引：0，他引：3
对于直流绝缘子表面电位分布的解释，传统的解释为由于盐密的影响和电导的作用。通过大量的实验总结，认为起主要作用的是水的极化作用，其中不只是盐密电导的作用。从而提出关于湿闪问题新观点。比较好的解释了潮湿天气及盐密较低情况时直流绝缘子串在额定电压下就发生闪络的特殊现象。 相似文献
13.
14.
In this letter, we introduce a novel passive transmission line of negative refractive index (i.e., left-handedness) based on identical symmetrical lattice type structures [thus called "lattice type transmission line" (LT-TL)]. The dispersion characteristic and the transmission response of the proposed LT-TL are analyzed. While all the other left-handed passive transmission lines are of high pass, the present passive left-handed transmission line is of low pass. Compared with a conventional transmission line, the LT-TL has a phase shift of 180° in the entire wide pass-band. 相似文献
15.
In this letter, we introduce a novel passive transmission line of negative refractive index （i.e., left-handedness） based on identical symmetrical lattice type structures [thus called ＂lattice type transmission line＂ （LT-TL）]. The dispersion characteristic and the transmission response of the proposed LT-TL are analyzed. While all the other left-handed passive transmission lines are of high pass, the present passive left-handed transmission line is of low pass. Compared with a conventional transmission line, the LT-TL has a phase shift of 180° in the entire wide pass-band. 相似文献
16.
对于电力工程建设费用的非线性问题，基于灰色系统理论，提出了一种成本费甩顸测与时间成本优化决策的新方法。 相似文献
17.
本文设计了一种智能变压路灯节电控制系统,通过单片机控制单元变压器抽头的切换以控制负载上输出电压,达到节电控制要求,通过此方案可以做到节电30%左右,同时为了提高系统的使用寿命,设计了过压或欠压故障报警等模块。 相似文献
18.
The modern travelling wave based fault location principles for transmission lines are ana-lyzed. In order to apply the travelling wave principles to HVDC transmission lines, the special tech-nical problems are studied. Based on this, a fault locating system for HVDC transmission lines is developed. The system can support modern double ended and single ended travelling wave princi-ples simultaneously, and it is composed of three different parts: travelling wave data acquisition and processing system, communication network and PC based master station. In the system, the fault generated transients are induced from the ground leads of the over-voltage suppression ca-pacitors of an HVDC line through specially developed travelling wave couplers.The system was applied to 500 Kv Gezhouba-Nanqiao(Shanghai)HVDC transmission line in China. Some field op- eration experiences are summarized, showing that the system has very high reliability and accu- racy,and the maximum location error is about 3 km(not more than 0.3% of the total line length). Obviously, the application of the system is successful, and the fault location problem has finally been solved completely since the line operation. 相似文献
19.
基于虚拟仪器技术的分布式过电压在线监测系统 总被引：2，自引：0，他引：2
提出了一种基于虚拟仪器的分布式过电压在线监测系统.监测系统由数字测量仪器组成实现数据采集、分析处理、过电压诊断和报警等功能,其网络通信采用CORBA技术实现在异构环境下中心监控站和各个工控机之间的远程访问和监控.系统的仿真研究和现场测试均表明该系统能够基本实现电能质量各项指标的监测和分析功能,并具有实时性好,可靠性高,开发成本低等特点. 相似文献
20.
Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ... 相似文献