Backflashover simulation of HV transmission lines with concentrated tower grounding

For high voltage (HV) transmission lines (TLs) the backflashover phenomenon can occur when lightning strikes a tower or a shield wire (SW). In this paper, the backflashover phenomenon of typical HV-TLs has been studied. The simulation code, based on ATP/EMTP program, accounts for both the discharge process between the arcing horns of insulator strings, by means of a leader progression model and the non-linear transient behaviour of tower grounding systems consisting of vertical rod(s). The lightning current ranges, causing back flash in a 161 kV-50 Hz single circuit line with two grounded SWs, have been investigated in detail. Numerical results of the investigations are in good agreement with actual behavior of the studied TL.     

自动转换开关合闸涌流对异步电动机负载的影响

针对电动机失电存在残余电压和异步电动机双电源开关转换时可能会产生较大的合闸涌流和过电压问题,通过Matlab仿真软件研究电动机负载电源转换的暂态特性,寻找备用电源合适的合闸时刻。对智能化自动转换开关（ATSE）控制器的设定具有一定的指导作用。     

基于正规形理论的多馈入交直流输电系统非线性模式分析

传统的特征根分析法不能揭示电力系统的非线性相关作用.正规形理论将非线性系统通过坐标变换,使得原系统与一个线性系统二阶或更高阶等价.将该方法应用到电力系统稳定分析中,既保留了小信号法的优点,又考虑了不同振荡模式间的非线性作用,适用于系统大扰动后的低频振荡特性分析.在对一双馈入交直流并联系统建立动态方程的基础上,运用正规形理论,分析了多馈入交直流系统低频振荡模式的非线性相关作用.结果显示,系统中各种模式是相互影响的,不同运行方式下影响程度也不相同,当系统重载且直流带调制方式下时,区间振荡模式与直流调制模式间的非线性作用最强.时域仿真验证了这一结果.     

云广±800 kV特高压直流输电线路耐雷性能研究

国内外运行经验表明,雷击是造成输电线路跳闸的主要原因。基于杆塔的多波阻抗模型和基于先导发展的雷电屏蔽模型,分析了云广±800 kV特高压直流输电线路的反击、绕击耐雷性能及其影响因素。结果表明：随着杆塔高度的降低,冲击接地电阻的减小,线路反击性能增强;随着保护角的减小,地面倾角的减小,海拔的降低,线路雷电屏蔽性能增强;引起特高压输电线路雷击故障的主要因素是雷电绕击,建议特高压输电线路采用负保护角运行。     

Rheological behavior of multi-sized SiC inks containing polyelectrolyte complexes specifically for direct ink writing

In order to simultaneously improve both the solid loading and rheological behavior of ceramic ink during direct ink writing (DIW) process, the polyelectrolyte complexes have been used as rheological modifiers. Based on the Funk-Dinger function, the maximum solid loading of multi-sized SiC ink reached 63 vol%. The viscoelasticity of SiC inks with different [COOH]:[NH_x] molar ratios was investigated and the mechanism of polyionic chains on rheology was analyzed. When the [COOH]:[NH_x] molar ratio was 1:0.1, the SiC ink exhibited excellent thixotropic behavior and formability. The effect of particle size on rheological behavior of SiC ink was investigated to clarify the correlation between polyelectrolyte complexes and multi-sized SiC.     

±500kV双回进线的高压直流换流站雷电侵入波防护(英文)

In order to obtain reasonable schemes of arrester in converter stations, the arrester scheme of "Xiluodu-Guangdong HVDC ± 500 kV double circuit transmission" project against lighting induced overvoltage, which was designed according to the main principle of lightning protection in converter station, is discussed. A calculation of the lighting induced overvoltage in Zhaotong converter station un- der various operation modes is performed with ATP-EMTP software, then the surge arrester configuration of the converter station is decided, and the arrester protection schemes of smoothing reactor and neutral line are studied. It is concluded that additional protection is necessary because of the relatively large gap between protected disconnecting switch and arrester of metallic return transfer bus. Plus, the smoothing reactor (SR) arrester near the valve hall could be removed to improve the scheme’s economic performance.     

Adult-child 3D backward face aging model (3D B-FAM)

Face aging has been widely considered in many studies regarding all the potential applications. However, the de-aging known as the rejuvenation or backward modeling has recently received more attention. Previous studies mainly focused on rejuvenating faces from aged adults into young adults using two-dimensional (2D) models. In this work, we propose an extension of a previous 2D adult-child B-FAM into 3D model. This model allows a digital face appearance rejuvenation within a range of [75–3] years old. To evaluate the performances of the proposed approach, first, we proposed two performance evaluation modes, namely: Generic Perception Based and Biometric Verification Mode. Then, the performances have been evaluated over our own 3D database, called Face Time-Machine database constructed using 75 females and 70 males, leading to 500 textured surface meshes. Finally, results show that they are perceptually satisfying and system performance increases by using the faces obtained from our model.     

Hybridization of g-C3N4 quantum dots with 1D branched TiO2 fiber for efficient visible light-driven photocatalytic hydrogen generation

The hybrid 1D branched TiO₂ loaded with g-C₃N₄ QDs was successfully fabricated that plays a significant role in photocatalysis. The 1D branched TiO₂ prepared by electrospinning followed by alkali-hydrothermal process, and g-C₃N₄ QDs were grafted over it by a chemical vapor deposition method. The composite display enhancement in photocatalytic hydrogen evolution is about 10.57 mmol. g⁻¹.h⁻¹ in comparison to the g-C₃N₄ sample that only produces 0.32 mmol. g⁻¹.h⁻¹ while the HBTiO₂ sample evolved a negligible amount of hydrogen under visible light. The composite sample shows quantum efficiency for HER at 420 nm light is 18.6% that is much higher than the other two samples. The specific surface area of the composite sample is 92.39 m²g^-1 that is about 13 times more than bulk g-C₃N_4. The bandgap of HBTiO₂/g-C₃N₄ QDs, g-C₃N₄, and HBTiO₂ samples calculated as 2.71 eV, 2.67eV, and 3.24eV, respectively. The TRPL spectra imply that the duration of the lifetime of composite becomes longer which effectually overwhelm the electron-hole recombination. The 1D branched TiO₂ fiber reduces the charge recombination by fast transfer of electron while g-C₃N₄ QDs facilitate the visible light absorption by improving the optical properties. The formation of the type II heterostructure system remarkably promotes the separation and transfer of electron holes and facilitates the photo-reduction reaction.     

基于组合型算法的风电并网地区电压闪变参数识别

针对矩形波调制下的闪变信号模型,提出优化能量算子以改善闪变包络提取精准度。将最大旁瓣衰减速率（MSLD）截断窗作为原始母窗,通过卷积运算构造频谱性能突出的MSLD自卷积窗（MSLD-SCW）函数。基于谱线插值原理推导出2阶 SCW函数的参数修正公式,据此实现闪变幅值与频率参数的处理与识别。与对照组算法的仿真结果表明,研究组在单频调制、多频调制、含有整数次谐波与次/超同步分量、基频波动及含高斯噪声等工况下,均保持较高的两大闪变包络参数识别准确性。最后,将组合优化算法应用于新疆某地区实际电网闪变参数识别,验证其工程实用性。