摘要：低压微网中,各并联逆变器之间的连接线路因长度、损耗等不同导致各逆变器并联线路阻抗存在明显差异,在常规下垂控制下,各并联逆变器间有功功率存在无法均分的问题。针对上述问题,提出了一种基于虚拟阻抗的自适应控制策略。首先,以逆变器功率传输特性与阻性下垂控制方程为基础,分析并联逆变器在线路呈阻性时有功功率分配不均的原因;其次,在传统定值虚拟阻抗基础上,通过引入并联逆变器的输出功率差构造虚拟阻抗,自适应地补偿线路阻抗差异,在不获取本地线路阻抗参数的情况下实现功率均分;最后,在MATLAB/Simulink仿真平台上建立逆变器并联系统的仿真模型,进行验证和分析。结果表明,所提方法能有效实现逆变器间有功和无功功率的均匀分配,且适用于本地负载不同的情形。基于自适应虚拟阻抗的控制策略改善了并联逆变器间功率的均分水平,可为低压微网中并联逆变器功率控制的优化设计提供参考。

摘要：MoS_2 samples with controllable morphologies and structures were synthesized using surfactantassisted hydrothermal *** effects of surfactants（PEG,PVP,P123,SDS,AOT,and CTAB）on the morphologies and structures of MoS_2 samples were *** results revealed that spherical,bulk-like,and flower-like MoS_2 particles assembled by NH4~＋-intercalated MoS_2 nano-sheets were *** morphologies of the MoS_2 samples and their structures（including the slab length and the number of stacked layers） of MoS_2 nano-sheets in these samples could be controlled by adjusting the ***-dispersed spherical MoS_2 particles could be synthesized with PEG via the creation of MoS_2 nano-sheets with slab lengths shorter than 15 nm and fewer than six stacked *** formation mechanisms of these MoS_2 samples created via surfactant-assisted hydrothermal processes are ***,the catalytic activities of MoS_2 samples for anthracene hydrogenation were evaluated in a slurry-bed *** catalyst synthesized with the surfactant PEG exhibited the highest catalytic hydrogenation *** with the other catalysts,it had a smaller particle size,mono-dispersed spherical morphology,shorter slab length,and fewer stacked layers;these were all beneficial to exposing its active *** work provides an efficient approach to synthesize transition metal sulfides with controllable morphologies and structures.

摘要：根据肇庆学院的办学定位和社会对生物科学专业人才的需求情况,结合生物科学专业自身的特点和发展趋势,提出了一套新的实验课程体系.新体系将生物科学专业实验课程分为基础操作实验,形态观察实验,验证性实验及综合性、设计性实验4大类型,并将实验室按实验类型进行重新调整.