In this paper,subnanosecond-pulse and one-nanosecond-pulse generators are used to study the breakdowns in highly overvolted gaps in atmospheric pressure air.With different cathodes,we measured the applied voltage and ...In this paper,subnanosecond-pulse and one-nanosecond-pulse generators are used to study the breakdowns in highly overvolted gaps in atmospheric pressure air.With different cathodes,we measured the applied voltage and discharge current to investigate the dynamic characteristics in the subnanosecond breakdown during the generation of a supershort avalanche electron beam.Especially,characteristics of dynamic displacement current are presented in the current paper,which is detected between the ionization wave front and a plane anode.It is shown that during a subnanosecond voltage rise time,the amplitude of the dynamic displacement current can be higher than 4 kA.It is demonstrated that the breakdown in the air gap is assisted by ionization processes between the ionization wave front and a plane anode.展开更多
随着柔性直流(direct current,DC)异步互联工程相继推进,高水电占比高带来的超低频振荡问题威胁着电力系统频率的稳定。针对超低频振荡现象的发生,提出基于柔性直流输电即电压源换流器的高压直流输电(voltage source converter based hi...随着柔性直流(direct current,DC)异步互联工程相继推进,高水电占比高带来的超低频振荡问题威胁着电力系统频率的稳定。针对超低频振荡现象的发生,提出基于柔性直流输电即电压源换流器的高压直流输电(voltage source converter based high voltage direct current transmission,VSC-HVDC)系统的附加频率控制策略。首先,构建含水电、火电机组的频率响应模型,通过阻尼转矩分析揭示超低频振荡产生机理,明确各类调速器参数以及不同水电占比对系统超低频振荡发生的影响;随后,根据直流电容电压与交流系统频率耦合特性,对换流站参与抑制超低频振荡机理进行研究,提出换流站虚拟惯性与V_(DC)-f下垂的控制方式,并通过约束条件对虚拟惯性与下垂参数进行设计;最后,基于MATLAB/SIMULINK平台搭建含水电、火电机组的负荷频率控制模型,通过对比水轮机参数优化方法验证所提方法的有效性。展开更多
基金Project supported by Russian Foundation for Basic Research （12-08-91150-FOEH_a and 12-08-00105-a）, National Natural Science Foundation of China （51222701, 51207154, 51211120183）, and the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists （2012T1G0021）.
文摘In this paper,subnanosecond-pulse and one-nanosecond-pulse generators are used to study the breakdowns in highly overvolted gaps in atmospheric pressure air.With different cathodes,we measured the applied voltage and discharge current to investigate the dynamic characteristics in the subnanosecond breakdown during the generation of a supershort avalanche electron beam.Especially,characteristics of dynamic displacement current are presented in the current paper,which is detected between the ionization wave front and a plane anode.It is shown that during a subnanosecond voltage rise time,the amplitude of the dynamic displacement current can be higher than 4 kA.It is demonstrated that the breakdown in the air gap is assisted by ionization processes between the ionization wave front and a plane anode.
文摘随着柔性直流(direct current,DC)异步互联工程相继推进,高水电占比高带来的超低频振荡问题威胁着电力系统频率的稳定。针对超低频振荡现象的发生,提出基于柔性直流输电即电压源换流器的高压直流输电(voltage source converter based high voltage direct current transmission,VSC-HVDC)系统的附加频率控制策略。首先,构建含水电、火电机组的频率响应模型,通过阻尼转矩分析揭示超低频振荡产生机理,明确各类调速器参数以及不同水电占比对系统超低频振荡发生的影响;随后,根据直流电容电压与交流系统频率耦合特性,对换流站参与抑制超低频振荡机理进行研究,提出换流站虚拟惯性与V_(DC)-f下垂的控制方式,并通过约束条件对虚拟惯性与下垂参数进行设计;最后,基于MATLAB/SIMULINK平台搭建含水电、火电机组的负荷频率控制模型,通过对比水轮机参数优化方法验证所提方法的有效性。
