基于节点动静态指标的电网节点重要度的评估研究

随着智能电网技术的不断发展,对高可靠性的智能电网的精确评估提出了更高的要求。智能电网中重要节点的故障将会导致大规模停电,因此对智能电网中重要节点的评估是评估智能电网可靠性程度的重要体现。文中针对节点所处的局部环境、全局属性、网络拓扑结构以及节点所承载负荷等级等多个不同的动静态综合指标进行研究,以这些综合指标模型来评估节点在智能电网中的重要度,最后使用TOPSIS方法将动静态指标糅合,共同对智能电网节点重要度进行评估,并对IEEE-30节点进行了仿真验证。结果显示节点6的重要度较高,应对其重点保护。     

基于熵的复杂电网的脆弱性识别与评估

电力系统线路发生扰动时会出现潮流转移,电网中的一些脆弱对潮流转移很敏感并且对故障传播起着十分重要的作用,识别出电力系统中关键的线路和节点对于提高电网安全性抑制故障传播有重要意义。根据熵的基本理论,利用潮流熵反映系统的运行的不均一性。考虑线路的承载能力并且结合潮流转移和分布特性建立支路脆弱性模型,根据节点的网络结构和运行状态建立节点脆弱性模型。通过对IEEE39节点进行模拟计算,当节点的潮流分布熵越小时潮流分布越不均匀,节点越脆弱,支路潮流熵越大时,支路越稳定。通过与其他方法比较,本文结论得以验证。     

分散式风电接入配电网的电压稳定性研究

针对双馈式风电场接入配电网影响原系统电压稳定的问题。采用基于短路容量的电压稳定指标,分析配电网接入风场前后各节点电压和电压稳定指标的变化情况。采用12节点的35 kV标准放射型配电网,应用MATLAB中Simulink及其电力系统仿真工具箱（SimPowerSystems）建立了相应的仿真模型进行详尽的仿真研究。分析了不同风电渗透率以及接入位置对配电网电压的影响,给出了负荷点电压随风电渗透率的变化曲线;通过给定负荷母线短路容量和在线计算的保持电压稳定的最小短路容量来评估电网的电压稳定性。     

基于节点重要度和风险因素的保护定值失配点校核研究

为降低电网结构日渐复杂化后继电保护的运行风险,本文基于系统网络的拓扑结构、节点聚合程度和业务类型提出了复杂网络下重要节点的辨识方法。结合三标度层次分析方法计算出系统网络节点的两个权重指标,以此完成对系统网络关键节点的辨识。此外,利用Markov模型分析方法对失配点转移后的保护定值进行风险评估,以获取系统网络最低失配风险下的保护定值。通过仿真验证本文所提的方法能够综合体现系统网络各节点的重要程度,并合理配置保护失配点,为有效评估电力系统保护运行风险提供了较高的参考价值。     

基于耦合振子模型的含风电电力系统聚类同步

针对含风电的电力系统受到扰动后发生严重的系统同步问题,提出基于Kuramoto模型的网络耦合聚类同步方法。应用图论理论建立电力网络收缩模型,在此基础上建立基于Kuramoto耦合振子模型电力系统等值模型,并提出基于动态耦合强度的电力网络聚类算法,该方法在系统发生扰动后能够快速、准确地将系统内振子的同步状态进行聚类。通过含有风电场的39节点新英格兰系统进行验证,仿真结果表明,通过聚类后各机群分析可以更清晰地了解电网的同步状态,避免系统进一步崩溃。     

基于转移负荷法的城市电网合环

在电网分区运行的背景下,针对边界110kV站点的合解环问题,从电网开合环的潮流计算入手,分析影响合环潮流的因素,得出母线间电压相角差对合环潮流的影响最大;在此基础是,提出一种以限制合环潮流为目标,通过转移负荷的边界站点合环方案制定方法。并通过电力系统综合程序PSASP对用该方法制定的方案进行了仿真验证,仿真结果验证了该方法的有效性和实用性。     

负荷特性对电力系统低频振荡的影响

负荷作为电力系统的重要组成部分,其特性对互联电网低频振荡具有重要的影响。本文在研究了电力系统低频振荡基本分析方法和电力负荷基本特性的基础上,建立了考虑动态负荷特性的用于研究低频振荡的电力系统线性化模型,形成多机系统的状态矩阵。以4机2区系统为研究对象,采用模态方法分析系统状态矩阵的阻尼比等结果随系统负荷模型参数变化的变化轨迹,从而获得不同负荷特性对系统低频振荡的影响。     

基于改进栈式自编码算法的中期负荷预测研究

综合考虑影响电力系统中期负荷预测的各个因素并提高预测精度,提出了基于改进栈式自编码算法的中期负荷预测方法。利用ICA进行特征提取,筛选主导的影响因素并对数据进行归一化处理,结合模糊理论构建气温因素的隶属度关系,通过参数自适应微分进化算法对栈式自编码算法参数展开在线优化,进而匹配最佳基于改进栈式自编码算法的组合中期负荷预测模型,并展开案例分析。其结果表明：该改进算法通过影响因素筛选、参数选择与优化,能够有效避免参数选择的盲目性,将气温动态因素进行模糊化处理,能够进一步提高预测精度,其预测结果优于PSO-SVM算法,与实际结果更为接近,且稳定性好,为电力系统负荷预测提供了重要手段。     

基于复杂网络和风险理论的电力系统脆弱性评估

基于复杂网络理论利用小世界模型对大型电力系统进行拓扑建模,建立电力系统的连接矩阵,该矩阵含有小世界模型全部特征参数的信息。鉴于干扰因素对电网运行的影响最终都是通过电网的连通性来体现,于是引入电网整体连通性和通道损失率两个指标。干扰因素源于电网的结构特性和电气特性。故从这两方面对电网的脆弱性进行评估。在结构特性上,依次切除节点和线路,求出相应的电网整体连通性和通道损失率;在电气特性上,选取影响电网稳定运行的两个最主要的因素,即电压幅值和功角差,并建立其与电网连通性的关系,求出相应的电网整体连通性和通道损失率。取基于结构特性的通道损失率与基于电气特性的通道损失率的乘积作为电网脆弱性评估值。利用IEEE30节点系统进行仿真并对电网各线路和节点进行脆弱性排序,说明了该方法的合理性与有效性。     

城市电力规划负荷预测之我见

在城市电网规划工作中,电力负荷预测是电力系统规划的基础和重要组成部分,是合理确定城市电源电网规模和布局的基本依据。文章对城市电网电力负荷预测模型方法进行简单阐述,力负荷综合预测体系进行了详细分析研究,最后结合当地电网规划设计实例,详细分析了空间负荷预测法在城市电网规划设计中的应用。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its