考虑电流指令跟踪能力的PQ控制逆变型分布式电源故障模型

从逆变型分布式电源(IIDG)的数学模型、控制原理和参数设计角度出发,分析不同参数、故障前工况和故障严重程度条件下变流器电流对其指令的跟踪情景,进而提出一种考虑变流器电流指令跟踪能力的IIDG对称故障模型。该模型根据变流器电流能否准确跟踪指令将IIDG等值为压控电流源和压控电压源这2个阶段,可更加准确地反映对称故障期间IIDG的控制特性。与现有方法及电磁暂态仿真软件计算结果的对比分析表明,所提方法在简化计算的同时具备更高的计算精度。     

电流互感器二次负载校验软件开发

针对电流互感器10%误差下的二次负载阻抗校验,介绍10%误差曲线的现场测试及二次负载校核方法,并在此基础上开发电流互感器二次负载校验软件,实现电流互感器二次负载校验的自动化。应用实例表明,该软件计算结果真实、可靠,实用性强。     

山东电网日内电力平衡动态评估系统

随着外电入鲁比重的不断提高,加之风电等新能源发电规模的不断扩大,给山东电网的电力平衡带来新的问题。分析影响电力平衡的各种因素,并通过综合能量管理系统(EMS)、电网调度生产管理系统(OMS)和日前计划系统信息,构建了主要包含日内计算旋转备用、电力平衡影响偏差、新能源接纳能力等指标的日内电力平衡动态评估系统,该系统能够为调度人员提供电力平衡情况的动态参考,为日内电网出力平衡调度提供重要的决策依据。     

A comparison of partially acetylated nanocellulose,nanocrystalline cellulose,and nanoclay as fillers for high‐performance polylactide nanocomposites

Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (Cloisite^TM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257.     

阻燃聚丙烯的研究进展

基于聚丙烯的热分解机理,依照材料设计的思路,总结并概括出阻燃聚丙烯的开发已从最开始的单纯的配比添加向深层次的材料设计转变的研究方向。重点概括并论述了当前阻燃聚丙烯材料的开发设计思路,并举例分析了三种层面上的阻燃聚丙烯的国内外的研发进展及其不足。     

PA6/SMA/N-PMI共混物的制备及其性能研究

采用熔融共混法制备了尼龙6/苯乙烯-马来酸酐共聚物/N-苯基马来酰亚胺共混物(PA6/SMA/N-PMI),并利用DSC、TGA及力学性能测试等手段研究了SMA用量对PA6/SMA/N-PMI共混物熔融结晶行为、热学性能以及力学性能的影响。结果表明,共混物的最大分解温度较纯PA6有较大提高;SMA用量的增加,共混物的结晶温度、结晶度以及熔融焓均先降低再升高;当SMA用量为5份时,共混物的弯曲强度、弯曲模量以及热变形温度均达到最大值,分别为113.8、3 053 MPa及61.3℃,较纯PA6分别提高了25.1%、28.0%及19.0%;拉伸强度在SMA用量为7.5份时达到最大值81.4 MPa,较纯PA6提高了17.1%。     

嘧菌酯的新合成方法

报道了一种广谱高效杀菌剂嘧菌酯的新合成方法,首先以2-氯苯甲腈与4,6-二羟基嘧啶为原料催化合成4-羟基-6-（2-氰基苯氧基）嘧啶,氯化得到4-氯-6-（2-氰基苯氧基）嘧啶.将4-氯-6-（2-氰基苯氧基）嘧啶与（E）-2-（2-羟基苯基）-3-甲氧基丙烯酸甲酯耦合,生成（E）-2-（2-（6-（2-氰基苯氧基）嘧啶-4-基氧）苯基）-3-甲氧基丙烯酸甲酯（嘧菌酯）.3步总收率为79.8％（以2-氯苯甲腈计）,原药质量分数为97％.     

基于3DMax技术的胡杨茎生长模拟

植物生长模拟研究,是利用计算机技术以可视化的形式描述植物的生长状态。本研究在综合国内外相关研究成果的基础上,以南疆胡杨茎为研究对象,通过对胡杨茎的生长因子及结构形态的研究,提出一种基于三维结构的胡杨茎生长模型,并运用3DMax技术建模,实现胡杨茎的生长形态的可视化。本研究能促进人们对胡杨生长过程的理解和感知,为分析胡杨结构功能关系、调控生长模式等提供重要参考。     

Identification of rational approximate models inH∞ using generalized orthonormal basis

Robust identification with FIR models fails to be successful when the number of coefficients to be estimated becomes large, caused by lightly damped modes of the plant or poles very close to the unit circle. The paper presents a two-stage algorithm to obtain a low-order approximate model in frequency domain in a generalized orthonormal basis with guaranteed H^∞ error bound for deterministic linear time-invariant stable systems, the first stage being an L^∞ rational approximation and the second nonlinear step being an H ^∞ rational approximation     

Evolutionary multiobjective optimization for base station transmitter placement with frequency assignment

We propose a new solution to the problem of positioning base station transmitters of a mobile phone network and assigning frequencies to the transmitters, both in an optimal way. Since an exact solution cannot be expected to run in polynomial time for all interesting versions of this problem (they are all NP-hard), our algorithm follows a heuristic approach based on the evolutionary paradigm. For this evolution to be efficient, i.e., goal-oriented and sufficiently random at the same time, problem-specific knowledge is embedded in the operators. The problem requires both the minimization of the cost and of the channel interference. We examine and compare two standard multiobjective techniques and a new algorithm - the steady-state evolutionary algorithm with Pareto tournaments. One major finding of the empirical investigation is a strong influence of the choice of the multiobjective selection method on the utility of the problem-specific recombination leading to a significant difference in the solution quality.