基于三电平光伏并网逆变器控制系统的研究与实践

设计了一种基于三电平的光伏并网逆变器,实现空间矢量控制策略、最大功率点跟踪、防孤岛检测等功能。提出了基于同步PI内环和直流电压外环的双闭环控制系统。实验证明：该装置具有较好的实时性、实用性和可靠性。     

Nitrogen air lasing induced by multiple filaments array

Air lasing emission by launching intense ultrafast laser pulses in atmosphere has recently attracted increasing interest in the ultrafast laser science and atmospheric science fields, especially for remote sensing techniques. We demonstrated the fluorescence emissions at 337 nm, 357 nm and 391 nm induced by multiple filaments using four kinds of step phase plates. Our results have indicated that the fluorescence signal has been amplified as it propagates along the filament through amplified spontaneous emission (ASE), and the fluorescence intensity is also enhanced in the backward direction via multiple filaments. Furthermore, the gain coefficient through ASE is increased with the number of filaments.