Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line (GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters (rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a>90 kV RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m⁻¹ and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.     

电容式电压互感器内电缆绝缘层击穿分析

电缆在实际运行中会受到电磁场、热能、机械振动及水分等因素影响,导致外绝缘性能下降,进而在中间变压器内部发生放电现象。为保证电气设备安全运行,基于电缆主绝缘材料的老化机理,通过开展绝缘电阻试验、介质损耗试验、绝缘材质分析、结构检查及分析等,找到电容式电压互感器电缆绝缘层击穿的原因并提出有效的预防措施,提升电缆绝缘材质的绝缘性能。     

500 kV输电线路OPGW引下线弧光放电原因分析及防范措施研究

为分析500 kV输电线路光纤复合架空引下线对龙门架空气间隙击穿放电原因,结合空气间隙击穿原理,通过对放电点、接地网导通性及线路覆冰情况排查,发现光纤复合架空引下线覆冰,导致光纤复合架空引下线与龙门架之间的空气间隙不足,故障短路电流使光纤复合架空引下线产生高电压并对龙门架构架放电。最后提出新建工程引下光缆与杆塔或构架本体间距不小于50 mm,改造工程线夹之间新增长度不小于50 mm,电弧放电后应检查接地网完整性等防范措施。     

平行耦合带通滤波器的分析与设计

微波电路中,平行耦合带通滤波器应用极为广泛。基于提高带通性能、缩短设计周期的目的,文章采用奇偶模分析与ADS(AdvancedDesignSystem)仿真相结合的方法,设计出一个中心频率为2.51GHz,相对带宽为10%的平行耦合微带线带通滤波器,各参数均满足设计要求。最终结果证明,此方法设计周期短、可靠性高。