Fast Analysis of Power/Ground Networks via Circuit Reduction

This paper presents an efficient algorithm for reducing RLC power/ground network complexities by exploitation of the regularities in the power/ground networks. The new method first builds the equivalent models for many series RLC-current chains based on their Norton＇s form companion models in the original networks,and then the precondition conjugate gradient based iterative method is used to solve the reduced networks,which are symmetric positive definite. The solutions of the original networks are then back solved from those of the reduced networks.Experimental results show that the complexities of reduced networks are typically significantly smaller than those of the original circuits, which makes the new algorithm extremely fast. For instance, power/ground networks with more than one million branches can be solved in a few minutes on modern Sun workstations.

An Integrated Tool for Power/Ground Network Design, Optimization,and Verification for Cell Based VLSIs

A CAD tool based on a group of efficient algorithms to verify,design,and optimize power/ground networks for standard cell model is presented.Nonlinear programming techniques,branch and bound algorithms and incomplete Cholesky decomposition conjugate gradient method (ICCG) are the three main parts of our work.Users can choose nonlinear programming method or branch and bound algorithm to satisfy their different requirements of precision and speed.The experimental results prove that the algorithms can run very fast with lower wiring resources consumption.As a result,the CAD tool based on these algorithms is able to cope with large-scale circuits.

Analysis on the Irregular and Asymmetrical Power/Ground Structure by PEEC Modeling

In order to provide some reference for the design of the power/ground system, a complicated power/ground system in time and frequency domains was analyzed, which is based on PEEC (Partial Element Equivalent Circuit). According to the actual requirements, characteristics of some common power/ground structures in time and frequency domains, such as SSN (Simultaneous Switching Noise), are obtained for the future research. The results show the first resonance point is changed with the structure of the power/ground networks.

The Research of Voltage Sag and Power Frequency Overvoltage on 110kV Resistance Grounding System

This paper researches the voltage transfer characteristics when one-phase ground fault occurred in the resistance grounding system, by using the theory of the asymmetric variable characteristics and the sequence network analysis of the -11 transformer, and concludes the scope of voltage sag and swell and the degree of power frequency overvoltage and their influencing factors in the 110 kV resistance grounding system. Accordingly this paper puts forward the resistance choosing principle: the resistance grounding coefficient must be equal to or greater than 10. So it can not only wipe out the voltage sag and voltage swell but also make sure the overvoltage is limited to electrical equipment allowing range. The method mentioned above is verified by simulation results of a 110 kV power system in ATP.

The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line

After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.

Research on single hole heat transfer power of ground source heat pump system

In this paper,the single hole heat transfer power of the ground source heat pump system in Hengshui is compared with data gained from thermal response test.The results show that maximum monitoring data of heat transfer power per meter in summer is 97.1% of the test data,and the average value accounts for 81.8%.The per meter heat power data through on-site thermal response test can provide references for designing engineering project and optimizing ground source heat pump system as these data do not vary greatly from the actual monitoring data.

Powerformer继电保护系统研究动态

介绍了发电机保护技术的最新进展--适用于Powerformer的继电保护系统。对目前提出 的4种面向Powerformer的保护新功能设计进行了详细介绍。最后总结了Powerformer继电保护 现阶段的研究成果,指出了其中存在的问题,提出了后续研究的思路。

基于数字式柱上断路器的线损计量及接地检测功能研发

本研究致力于开发实现线损计量和高阻接地故障检测功能的新型数字式柱上断路器自动化成套设备,适用于10 kV架空线路。通过对高压电容取电单元、数字化高精度电子式传感器、低功耗模组化智能终端的研究,旨在提高设备的运行效率,提高设备的安全性能,是我国目前最大检测结果显示,该设备在金凤区丰登镇试点成功应用,具有测量线损的高精度功能和检测高阻接地故障5000Ω以上的能力。

Study on Lightning Protection Design of DCS in a Nuclear Power Plant

DCS （distributed control system） plays a decisive role in the overall operation of a nuclear power plant. If DCS fails, it will seriously affect the normal production of nuclear power plant, causing great losses. So it is very important to take perfect lightning protection measures on DCS of the nuclear power plant. In this paper, according to the actual situation of DCS in a nuclear power plant, by controlling lightning point, securely booting lightning into the ground network, improving low-resistance ground network, eliminating ground loops, determining the safety space, surge protection of power and signal, a set of complete lightning protection design scheme was systematically put forward. Some specific lightning protection measures were highlighted, such as the DCS grounding, equipotential bonds and shields, and some specific considerations were put forward. All of these could offer reference in the practical application.

内蒙古地区强震动台站背景噪声与数据质量分析

计算了内蒙古地区193个强震动台站2022年连续观测数据的加速度功率谱密度,通过绘制不同时空、不同加速度计、不同频段的功率谱密度和功率谱概率密度函数图及背景噪声速度均方根值分布图,评估了该区强震动台站的背景噪声变化特征,对出现的功率谱密度异常进行了具体分析,并针对强震动台站数据异常检测及处理提出了相应的建议。研究结果显示:不同加速度计、不同时空强震动台站的背景噪声功率谱密度昼夜差异主要体现在1 Hz以上频段,且不同区域的昼夜差异变化较大;QA-2g型、JS-A2型和TDA-33M型三种加速度计在2 s频点的背景噪声功率谱密度随区域和三分向变化较小;从强震动台站2 s频点背景噪声的监控能得到可靠的观测数据异常,数据异常主要由加速度计零点漂移大、加速度计故障、脉冲干扰、系统参数有误造成,建议优化站点观测环境,进一步规范仪器安装、调试及JOPENS系统的参数配置和审核。

自我决定理论视角下在线学习力模型构建——基于扎根理论的质性分析

在线学习已经成为重要的学习方式之一,与之相对应的在线学习力成为一个热点问题。通过收集S校7位大学生的在线讲座信息、对Y校8位优秀网络教育学生进行访谈获取的资料,以自我决定理论为指导,基于扎根理论的三级编码方法,利用NVivo12.0质性分析软件构建了动机—行为—绩效的在线学习力模型,具体包括学习动机、学习投入、学习技能、学习情绪和学习绩效5个维度。其中,学习动机由目标倾向和价值意义组成;学习投入由意识认知、行为努力和社交支撑构成;学习技能落实在学习策略、信息能力和综合能力3个方面;学习情绪具有积极心态和负面情绪2个类别;学习绩效则体现在学习业绩和学习满意度2个层面。从教育视角来看,提高在线学习力必须强化在线学习体验,加强教师的教学设计和教学干预,完善在线学习绩效评价等。

航天地面电源加速寿命试验研究

以某航天地面电源为研究对象,开展加速寿命试验研究。首先,介绍了加速寿命试验的特点、目的和优点;然后,阐述了加速试验的方法和流程;最后,对加速寿命试验的结果进行了分析。结果表明,与传统的可靠性试验相比,加速寿命试验可有效降低试验成本、提升试验效率,具有绝对优势。

“光储直柔”建筑配电系统应用研究

以某项目为例分析“光储直柔”在建筑物中的应用,并对“光储直柔”系统的应用场景、建筑直流配电系统的关注点及“光储直柔”系统关键设备进行阐述。

石墨烯/三聚磷酸铝水性导电防腐涂料的制备及性能研究

以石墨烯为导电填料,三聚磷酸铝为防腐填料,水性环氧树脂作为黏结骨料,配置得出了一种用在接地电极表面的导电防腐涂料。通过附着力、导电性以及耐蚀性测试,再结合土壤模拟浸泡试验,研究不同石墨烯与三聚磷酸配比对涂层导电与防腐性能的影响,结果表明当m(G)∶m(EP)=17%,m(ATP)∶m(EP)=1%时涂层表现出了优异的导电性与抗腐蚀性,可以满足电力接地网使用要求。

基于公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程模拟

【目的】生成拟合公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程代表性时程集合。【方法】首先,结合非平稳地震动过程的强度-频率调制函数和平稳地震动过程的Clough-Penzien功率谱模型,建立全非平稳地震动过程的演变功率谱模型;其次,依据相关规范确定演变功率谱模型参数取值;然后,根据全非平稳地震动过程模拟的谱表示方法,编写MATLAB程序,生成全非平稳地震动过程代表性时程集合,计算其均值反应谱和规范反应谱拟合误差,并进行迭代修正。【结果】依据公路与城市桥梁抗震设计规范给出了不同场地类别和设计地震分组的演变功率谱模型参数取值;生成的代表性时程集合具有全非平稳地震动的典型特征,其均值反应谱和规范反应谱整体拟合程度较好,平均相对误差均在5%以内。【结论】基于演变功率谱模型,通过编写全非平稳地震动过程模拟谱表示方法的MATLAB程序,可生成满足公路与城市桥梁抗震设计规范要求的全非平稳地震动过程代表性时程集合,其均值反应谱与规范反应谱拟合一致,验证了所给方法和MATLAB程序的有效性,可为桥梁结构抗震性能评估提供可靠的地震动输入。

A modified method for simulating non-stationary multi-point earthquake ground motion

A spectral-representation-based algorithm is proposed to simulate non-stationary and stochastic processes with evolutionary power,according to a prescribed non-stationary cross-spectral density matrix. Non-stationary multi-point seismic ground motions at different locations on the ground surface are generated for use in engineering applications. First,a modified iterative procedure is used to generate uniformly modulated non-stationary ground motion time histories which are compatible with the prescribed power spectrum. Then,ground motion time histories are modeled as a non-stationary stochastic process with amplitude and frequency modulation. The characteristic frequency and damping ratio of the Clough-Penzien acceleration spectrum are considered as a function of time in order to study the frequency time variation. Finally,two numerical examples are presented to validate the efficiency of the proposed method,and the results show that this method can be effectively applied to the dynamic seismic analysis of long and large scale structures.

浙江新材料科创高地支撑全球先进制造业基地建设的动力机制与实现路径

新材料是浙江省“315”科技创新体系三大科创高地之一,是支撑浙江建设全球先进制造业基地着重打造的4个世界级先进产业群之一。依据浙江省建设全球新材料先进制造业基地的目标与要求,构建由新材料科创高地为基本支撑,以“政、产、学、研、用”多元创新主体协同,以“制度、技术、人才、市场、资本”多要素协同为基本动力的新材料全球先进制造业基地建设动力机制模型,并据此提出加强新材料产业集群顶层设计、支持新材料产业研发创新、完善新材料产业集群价值网络、健全专精特新小巨人企业梯度培育机制的实现路径,为新形势下浙江新材料产业发展和新材料先进制造业基地建设提供借鉴。

站用10 kV系统中性点接地方式对避雷器地电位升安全限值的影响

随着电网容量变大和新型电力系统的发展,站用10 kV系统中性点接地方式发生改变,仍沿用系统中性点不接地方式下避雷器耐受接地网地电位(U_(GPR))升高的安全限值可能会导致避雷器在其他接地方式下出现安全事故。采用电磁暂态程序ATP-draw可以搭建不同中性点接地方式下U_(GPR)反击避雷器的模型,通过校核避雷器在U_(GPR)作用下动作过程中的吸收能量,得到了中性点接地方式对避雷器耐受U_(GPR)安全限值的影响规律:中性点不接地时,避雷器耐受U_(GPR)安全限值为10~23 kV,随线路对地电容变大而减小;中性点经消弧线圈接地时,U_(GPR)在消弧线圈和线路对地电容的串联回路中产生振荡,导致避雷器耐受U_(GPR)安全限值更低,安全限值主要由脱谐度与阻尼率决定,典型值为8~9.5 kV;中性点经电阻接地时,U_(GPR)大部分耦合至高压母线,使避雷器耐受U_(GPR)安全限值更高,并随线路对地电容和中性点电阻的增大而减小,大电阻接地工况下的典型值大于15 kV,小电阻接地工况下的典型值大于25 kV。

基于密集台阵的近场与远场地震动迟滞相干函数模型分析

迟滞相干性是表征地震动空间变化特性的一个重要指标,为研究近场与远场地震动的迟滞相干性的空间变化特性及其差异,基于美国UPSAR台阵记录的2004年Parkfield M_(w)6.0地震的近场记录,以及中国自贡台阵记录的2008年汶川M_(s)8.0地震的远场记录,分别分析了两个密集台阵近场和远场地震动的水平向和竖向相干函数随距离、频率的变化规律,对比了近场和远场地震动迟滞相干性的差异;将基于实际数据的迟滞相干性值与常用的三种相干模型进行拟合分析,揭示了不同相干模型的优势和局限性。结果表明:近场与远场地震动的相干性衰减速度有明显差异,在低频和近距离时,远场记录的相干性要明显大于近场记录;相干性随着距离和频率的衰减速度不同,相干函数模型需要对频率和距离项使用不同的参数描述;现有模型对近场和远场地震动的拟合效果差异较大,对远场记录的拟合效果要优于近场记录;三种模型对同一事件的拟合效果不同,多参数模型效果最好,双参数模型其次,单参数模型适用性较差。研究结果可为近场和远场区相干性模型的选用提供依据。