为掌握接地模块在雷电冲击电流下对接地体的降阻效果,指导防雷接地的优化设计和改造,在不同土壤环境和冲击电流幅值下,对接地模块的非金属包围层,及接地模块安装数量和位置对水平接地体冲击特性的影响进行了对比试验研究.结果表明,接地模块的降阻效果在小幅值冲击电流下更显著,在火花放电效应极其强烈的高土壤电阻率和大幅值电流下,接地模块与其极芯导体的冲击特性曲线几乎一致,围绕在极芯周围的非金属包围层降阻材料作用被淹没.在同样条件下,圆形接地模块的降阻效果优于方形和梅花形.水平射线上的接地模块,宜优先布置在首端注流点,其次为靠近射线末端,布置数量更多时,宜均匀分布在射线上.为提高技术经济性,接地模块的布置间距不宜过小;当达到饱和数量时继续并联加密接地模块对降阻作用不明显,可以通过串联加长模块的方式进一步减小冲击接地阻抗.

介绍了目前国家电网公司小电流接地方式的情况,针对该方式下单相接地故障的特点和存在的问题,阐述了快速隔离故障的必要性.对目前应用中不同的故障处理方法进行了论述,主要包括人工“拉闸试停”寻找故障线路、利用故障选线装置和故障指示器选线以及基于馈线自动化系统的故障处理技术.分析了上述几种方法的特点、技术发展现状和存在的问题,并结合实际应用效果,提出了相应的改进建议,指出馈线自动化系统是未来配电网故障处理的发展方向.

分析了电容器噪声产生机理,利用10 kV电能质量谐波源试验平台,开展工频基波叠加不同畸变率谐波电压条件下并联电容器的噪声试验研究,得出不同次谐波时电容器噪声变化曲线,分析谐波对10 kV并联电容器的影响程度,针对典型条件下电容器噪声频谱进行分析。试验结果表明,基波叠加谐波的激励信号作用下,电容器噪声频率主要集中于基波二倍频率、h+1次谐波频率、h-1次谐波频率和2h次谐波频率特征频率上。

为研究电容式电压互感器(CVT)因主电路工作在工频谐振造成其频率特性发生畸变而导致谐波测量结果失真问题,在仿真谐振型和速饱和型两种类型CVT的频率特性曲线基础上,通过电能质量扰动装置,进行110 k V两种型号CVT的谐波测量误差试验。试验验证了仿真模型的正确性且杂散电容也是影响CVT频率特性的原因之一。试验结果表明:通过CVT测量谐波幅值和相位存在很大的误差,某些频率下幅值最大可能达到实际值的2倍以上,最小仅为实际值的30%左右,相位也出现在某些频率下120°突变的问题;不同厂家不同型号的CVT之间的误差特性不同,而同厂家同型号CVT的谐波测量误差特性基本一致。最后针对现场大量应用CVT进行谐波测量的问题提出了应用电容式分压器测量、通过接地回路电流测量、采用带谐波测量功能的特种CVT测量以及对测量结果进行修正等改进意见。

为研究杆塔接地装置的冲击特性,准确掌握其雷电响应,设计了冲击大电流试验系统.在分析冲击电流发生器原理的基础上,计算放电回路的电气参数,并提出分布式冲击大电流试验系统.该系统由4台十字型对称分布的电流发生器组成,可在负载4 Ω的情况下产生峰值100 kA、波形为8/20 μs的标准雷电流.并选择典型的杆塔接地装置检验了该试验系统的试验能力.试验结果表明:在单级电容充电电压为185 kV情况下,产生波形7.64/18.45 μs、峰值100.358 kA的冲击电流,设计方案是有效可行的;接地装置的冲击接地电阻随着冲击电流幅值增大而减小.

Aiming at the deficiency of electric vehicles,this paper introduces a portable solar charger design and implementation, the charger is based on a UC2843 Boost converter,it collects electrical energy from solar panels, through the Boost converter,it can realize to charge the electric vehicle batteries on continuous.The Boost control circuit is simple and reliable,low cost,less peripheral elements.The experimental results show that the charger is convenient and practical,which can effectively extend the electric vehicle mileage,increase the life of the electric vehicle battery,it has a broad application prospect.

This paper describes design and implementation of a direct lightning current measuring apparatus for transmission lines.This apparatus can be used to measure the direct lightning current amplitude,polarity,and thunder-strike time.The measuring apparatus,adopting the high-performance ARM7 processor LPC2103 as its core,can simultaneously measure two channels of lightning current.Flexible data transmission mode and reliable system power supply design are applied with low cost and wide application.

In order to study the lightning impulse characteristics of grounding devices, the research on spark effect and inductance effect is taken as the principal line of this paper. Plus the feature of soil discharge, the high frequency response of grounding devices and the change regulation of soil electrical parameters are explored. Furthermore, three transient modeling methods which adopts circuit theory, electromagnetic field theory and dynamic modeling respectively are compared. The development of impulse characteristic tests of grounding devices is also commented. Through summary and analysis of the researches, several important and imperative technical problems needed to be solved and their elementary solutions are presented. The discharge form of soil and the size of discharge area could be approached by collecting soil discharge image by adopting X--ray films or high speed imagers. It is necessary to determine the critical breakdown field--strength and the residual soil resistivity of discharge area which are used in the transient modeling. The spark effect influenced range and the frequency dependence of the spark effect and the inductance effect need to be discriminated. It is suggested to analyze the frequency characteristics of the extensive grounding bodies, the complex structure grounding devices and the grounding devices by adopting the distributed parameters model, the concentrated parameters model and the electromagnetic model respectively. The impulse characteristics of grounding devices which are excited by the impulse current with high amplitude and short front time could be gained by adopting the high voltage and capacity impulse current test systems, and then be used in the field measurement of the impulse grounding resistance.

This article introduces the basic principle and configuration of lightning location system and its application in Jiangxi power system.The lightning short message model based on Short Message Service technology,realizes the function by cell phone short message to inquire lightning information,enhances the efficiency of searching lightning in Jiangxi power system,and achieves good result;in actual demand of Jiangxi power system,the lightning parameter statistic model was built on ArcGIS Engine platform,offered a way to the lightning research,based on this model,this article explored the law of lightning activities in Jiangxi power grid.

In order to draw and study the cloud-to-ground flash density map,the monitoring lightning data in 2004-2006 of Zhejiang Lightning Location System is selected as study samples,and the method--Grid Method for drawing high resolution cloud-to-ground flash density map using vast automatic monitoring data is presented. Based on flash density value of each grid,Jenk's Natural Breaks classification method is adopted to determine the natural arrangement of these values into five classes,eventually formed the cloud-to-ground flash density map of Zhejiang with 1km resolution with five grades. Through the terrain of Zhejiang Province,it's found that the cloud-to-ground flash density spatial distribution is closely relevant with the character of terrain and monsoon. By comparing Zhejiang power grid lightning-stroke fault points in 2004～2006 with the flash density ranks,the conclusion that the lightning-stroke fault number is positively correlated with the lightning ranks is gotten,which show off the effectiveness of the cloud-to-ground flash density map.

The paper presents some transmission methods used for data acquiring in lightning location and detection system such as audio modulating, power system networks, Internet and satellite communication. The protocol of communication applied for each method and its application in lightning location and detection system in power industry of the country are introduced. The transmission procedure of each method, its characteristics and the choosing criteria are stated. The coverage scope, location accuracy and detecting efficiency are improved by choosing detecting site through multi-approaches to meet the system requirements.

利用ASP+Java+数据库技术构建了雷电信息网站,以B/S(浏览器服务器)方式实现了雷电定位数据的图形化共享.使用户可通过浏览器访问网站的应用雷电数据,实时显示雷电趋势及查询线路雷击故障杆塔.

为解决电力企业在雷电定位系统应用中出现的海量信息处理、传输网络复杂及可靠性高的要求,提出了分层次的分布式雷电信息系统模型,该系统采用COM+技术、数据库技术、网络技术和GIS技术,利用雷电定位系统和雷电信息处理系统可实现实时动态雷电信息和雷电分析.通过COM组件的开发与应用,解决了大型复杂软件系统开发中的团队协作、系统的可扩展性和可维护性等问题.