Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds...Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.展开更多
光伏系统逆变器启动时,最大功率点跟踪(maximum power point tracking,MPPT)等内部控制算法会引起电流瞬态变化,从而干扰直流串联电弧故障诊断装置对故障特征的正确识别,造成误动作。为此,针对逆变器启动情况下电弧故障检测装置易出现...光伏系统逆变器启动时,最大功率点跟踪(maximum power point tracking,MPPT)等内部控制算法会引起电流瞬态变化,从而干扰直流串联电弧故障诊断装置对故障特征的正确识别,造成误动作。为此,针对逆变器启动情况下电弧故障检测装置易出现误动作的问题,提出一种基于无量纲特征量和灰色关联度的故障检测方法。首先分析了电弧故障RLC等效振荡模型,得出电弧电流信号在频域具有较宽的频带;然后分别对逆变器工况与电弧故障实测电流的频域特性进行了对比,发现正常工况与故障在1~20 kHz和40~60 kHz范围内的频谱在波峰陡峭度、所处位置等方面存在差别,使用峭度、偏度、峰值因子、冲击因子、裕度因子、波形因子等提取频谱特征,计算灰色关联度并进行故障识别;最后,分别使用模拟平台和实际光伏系统进行了试验验证。结果表明,所提方法可有效避免逆变器启动造成的干扰,提高故障识别的准确度。展开更多
为了更好利用叠加式双阻尼振荡模型(ABDOM,Accumulative Bi-Damped Os-cillation Model)来描述、预测和评估真实软件缺陷发现时序过程,在提出理想软件缺陷发现时序过程范型(ISPSDD,Ideal Sequential Process of Software Defects Discov...为了更好利用叠加式双阻尼振荡模型(ABDOM,Accumulative Bi-Damped Os-cillation Model)来描述、预测和评估真实软件缺陷发现时序过程,在提出理想软件缺陷发现时序过程范型(ISPSDD,Ideal Sequential Process of Software Defects Discovery)的基础上,对AB-DOM中软件缺陷发现阻尼a和软件缺陷发现周期阻尼b的规范化进行了进一步讨论,提出了软件缺陷发现时序过程质量评价指数Q,给出了其典型取值和相关意义,并将其引入ABDOM,最终得到了经过参数规范化和离散化改进后的ABDOM-Qd,并利用一个真实的工程实践项目数据对ABDOM-Qd进行了验证.展开更多
基金supported by Major Projects of Shanxi Province (202101030201001)。
文摘Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.
文摘光伏系统逆变器启动时,最大功率点跟踪(maximum power point tracking,MPPT)等内部控制算法会引起电流瞬态变化,从而干扰直流串联电弧故障诊断装置对故障特征的正确识别,造成误动作。为此,针对逆变器启动情况下电弧故障检测装置易出现误动作的问题,提出一种基于无量纲特征量和灰色关联度的故障检测方法。首先分析了电弧故障RLC等效振荡模型,得出电弧电流信号在频域具有较宽的频带;然后分别对逆变器工况与电弧故障实测电流的频域特性进行了对比,发现正常工况与故障在1~20 kHz和40~60 kHz范围内的频谱在波峰陡峭度、所处位置等方面存在差别,使用峭度、偏度、峰值因子、冲击因子、裕度因子、波形因子等提取频谱特征,计算灰色关联度并进行故障识别;最后,分别使用模拟平台和实际光伏系统进行了试验验证。结果表明,所提方法可有效避免逆变器启动造成的干扰,提高故障识别的准确度。
文摘为了更好利用叠加式双阻尼振荡模型(ABDOM,Accumulative Bi-Damped Os-cillation Model)来描述、预测和评估真实软件缺陷发现时序过程,在提出理想软件缺陷发现时序过程范型(ISPSDD,Ideal Sequential Process of Software Defects Discovery)的基础上,对AB-DOM中软件缺陷发现阻尼a和软件缺陷发现周期阻尼b的规范化进行了进一步讨论,提出了软件缺陷发现时序过程质量评价指数Q,给出了其典型取值和相关意义,并将其引入ABDOM,最终得到了经过参数规范化和离散化改进后的ABDOM-Qd,并利用一个真实的工程实践项目数据对ABDOM-Qd进行了验证.
