Testing Research about Characteristic Parameters of the Grounding Device at 750 kV Substation of Riyue Mountain,Qinghai

750 kV substation of Riyue Mountain, Qinghai is a substation that annual average thunderstorm days are the maximum at the same volt- age level and altitude in the wodd. We detailedly described testing methods and steps of 6 characteristic parameters for grounding device of 750 kV substation by using 8000S comprehensive test system, and scientifically judged overall performance of the grounding device. Moreover, we espe- cially emphasized key and difficult points in testing process, providing reference for the majority of grounding test workers.

Mathematical Modelling for Assessing Integrity of Power Systems Grounding Devices

This paper presents the development of a new technique to monitor the operating conditions of a grounding device of high voltage apparatus and systems without any diggings and forced outages. The model is based on the evaluation of the magnetic field distribution along the current-carrying horizontal element when it has been deteriorated or broken. A mathematical model which can be used to analyze and evaluate the integrity of the grounding device has been developed. Computer simulation studies were conducted to validate the effectiveness of the proposed model.

A GROUND SIMULATION-INSPECTION SYSTEM FOR AVIONIC DEVICES

The paper discusses the system function, structure of hardware and software of the ground simulating testing system for airborne electronic devices; an example of a practical simulation and inspection system is given. The system connects different kinds of microcomputers as DIMENSION 68000. SDK86, TP80T to form a distributed simulation and inspection network through an 8-terminal optic fiber communication net. The system can imitate the signal of the radar of a motional object and the ARINC429 signal of the navigation subsystem and atmosphere subsystem. It can be directly connected to the airborne electronic devices, receiving and processing real-time data from the airborne electronic devices, storing the data, fulfilling error analysis, drawing curves of the motive objects, printing tables of various test parameters. The system is easy to operate with perfect functions. The technique index accomplished and appraisal of the system are also given.

Analysis of the integrated test and evaluation methods of tidal current energy generating devices in the offshore testing site

Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.

Research on the Optimized Network Configuration of DC Blocking Device

HVDC transmission system has considerable impact on the surrounding power transformers when the system is running in the unipolar ground mode, which will cause the DC magnetic biasing phenomenon on transformers. This problem would be more serious, after commission and operation of UHVDC transmission system in China. According to the Guangdong power grid under the influence of DC magnetic bias seriously, but little research about the using of blocking device, this paper proposed an optimization scheme about the usage of blocking device combination. Firstly, the subject studied the method of suppressing transformer neutral point DC depending on analysis the mechanism of magnetic biasing, and then found out the changes of power grid after using the capacitance blocking device which is popular used by Guangdong power grid. The particle swarm optimization (PSO) has been used to find a better way to suppress the DC in power grid, and combined with NSGA to solve the mixed integer programming problem. The final data validation of this method is valuable in engineering application.

Grounding Systems for Power Supply Facilities

The goal of this work is creation of optimal grounding model at the substation 10/0.4 kV of the urban power distribution network. The electric current can pose a major threat to the man’s life and health. In addition to pose a threat for health, the rise of the short circuit, as a consequence of insulation faults, poses a threat to retirement of electric systems and fire risks. The reliable grounding system design has significant implications for protection of human being as well as for electrical facility protection. The set objective was performed on the base of analytical and software-based methods. Analytical method gives a qualitative indication at each step in analysis. It also allows evaluating the values effect on the result, but the method is not susceptible of tolerable accuracy, that is why analytical method serves as initial approximation in differentiating. Specified estimation can be performed in such software package as MATLAB or ETAP. Software-based estimation is based on the finite element method (FEM), the main advantage of which is the ability to create different forms of grounding and allows obtaining distribution graphs of the step potential on the earth’s surface and touch potential. The calculation results in comparison of analytical and software-based methods taking into account the grounding optimization. There are conclusions on the most effective ground network.

基于仿生机构学落地红枣聚拢装置的设计与试验

针对南疆地区目前落地红枣无法聚集、人工捡拾效率低、机械化程度不高等问题,在分析枣树种植模式及红枣物料特性的基础上,采用仿人手臂聚集红枣的方法设计了一种快速聚拢装置,并确定了各零部件的结构参数。利用三维建模软件SolidWorks与运动学仿真软件ADAMS,对聚拢装置进行了建模与运动学仿真,结果表明:红枣在聚集过程中,接触的速度都是从小到大再到小,没有急剧的突变现象,对红枣的损害程度较小,符合设计工作要求。以红枣聚集率为响应指标,以前进速度、曲柄转速、滚筒转速为影响因素,设计了正交组合试验,建立了各因素对聚集率指标二次多项式回归模型,并分析了各因素对聚集率的影响规律。通过多重响应方法中的主目标函数法对其参数进行了优化,获得了影响红枣聚集率的最佳参数,即前进速度为0.37 m/s、曲柄转速为58 r/min、滚筒转速为32 r/min,此时红枣聚集率为88.65%。研究结果可为后续落地红枣聚拢装置的改进和研发提供参考。

Performance Analysis of Corroded Grounding Devices with an Accurate Corrosion Model

Grounding devices are significant to the operation of the power transmission line and power equipment.The soil and leakage current can easily cause the corrosion of carbon steel grounding devices,resulting in power accidents.Therefore,most carbon steel grounding devices in service are already corroded,and the accurate calculation of grounding parameters for corroded grounding devices is important.However,most existing methods for calculating the grounding parameters of corroded grounding devices usually have the following disadvantages:1)They only consider whether the grounding devices are broken or not,and cannot analyze the grounding parameters of grounding devices with different corrosion degrees;2)They assume that the corroded grounding device is a conductor with a smaller diameter,and ignore the impact of the corrosion product layer,resulting in calculation errors.To solve the above problems,this paper establishes an accurate corrosion model for grounding devices based on the volume expansion coefficient of corrosion products.The grounding parameters calculation method for corroded grounding devices is proposed based on the boundary element method(BEM)and Galerkin’s method.Then the grounding performance of tower grounding grids with different corrosion degrees in different soils(uniform and layered)is analyzed.Finally,some features of grounding parameters of corroded grounding devices are given.This study can accurately calculate the grounding parameters of the corroded grounding devices and has far-reaching engineering significance for the safety of power equipment.

排岩机履带行走装置接地比压分布规律研究

针对目前接地比压分布不均匀问题,本文以排岩机为例,建立了履带行走装置接地比压计算数学模型。基于Solidworks、MATLAB软件,对排岩机重心空间坐标值与其受料臂旋转角度、排料臂上仰角度及车体回转支承旋转角度进行了拟合。进一步通过ANSYS Workbench仿真软件,证明了所建接地比压计算模型的正确性。研究分析了接地比压随受料臂旋转角度、排料臂上仰角度、排岩机车体回转支承旋转角度的变化趋势。这里研究成果可为各种履带行走设备整机的设计及其工作地基的处理提供一定的参考。

配电网中性点柔性接地装置四象限运行机理与控制方法

针对现有配电网柔性接地装置在进行接地故障处置时,易因网侧能量倒灌而导致直流侧电压失稳,甚至直流电容击穿的问题,分析注入电流与中性点电压间相角差随系统参数的变化规律,揭示系统参数变化对柔性接地装置输出有功功率、能量流向的影响机理,阐明造成系统能量倒灌的内在原因。在此基础上,提出一种具备四象限运行功能的柔性接地装置拓扑结构,在整流侧采用电压型三相半桥可控整流拓扑,并经配电变压器接入电网,能够维持能量在装置内双向流通,提升直流侧电压稳定性,同时实现直流侧供电自给。进一步提出基于四象限运行柔性接地装置的多目标复合控制方法,通过dq旋转坐标系下整流双环控制实现装置整流网侧单位功率因数运行及直流侧电压稳定,并由逆变侧控制对中性点电压进行快速精准调控。在PSIM(power simulation)仿真环境与10 kV真型配电网实验场中模拟各种运行和故障工况,对所提装置运行机理和控制方法进行验证,仿真与实验结果表明四象限运行柔性接地装置能有效解决现有柔性接地装置在网侧能量倒灌条件下直流侧电压失稳的问题,提升装置的运行和调控性能,实现接地故障快速安全可靠处置。

土壤冻结时考虑导体传热的 接地装置散流失效模型

西藏地区新能源送出走廊不可避免的会途经极寒冻土地区,接地装置面临着冻结失效的风险。以往的研究中,接地装置散流性能计算前提是将冻土考虑成静态水平分层结构,忽略接地装置与杆塔相连时整体的散热效应对土壤冻结结构的影响,导致实际运行中接地装置散流性能分析不准确。因此,该文首先建立考虑接地导体传热的土壤水热场耦合模型,计算得到杆塔散热条件下土壤的冻结结构;然后,在此冻结结构下构造接地装置冲击散流失效模型;最后,利用该模型与传统模型对比,探究接地导体的半径、长度和土壤初始温度等因素对接地装置散流性能的影响。研究表明,由于接地导体具有良好的导热性能,其所接触的土壤易形成局部冻结,与传统模型相比,-10℃低气温下相同接地装置失效时刻提前约18 d;若低温持续时间相同,半径6 mm的单根垂直接地导体达到3.3 m就不会失效,而传统模型下则是1.6 m,相差约2倍。此外,减小接地导体半径或降低接地导体导热系数均可减缓局部冻结。

“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。

突发公共卫生事件背景下医疗器械供应链脆弱性研究

突发公共卫生事件使医疗器械供应链表现出较强的脆弱性,有必要对脆弱性影响因素进行判断和评估。本文采用扎根理论与问卷调查相结合的方法对医疗器械供应链的脆弱性指标进行识别和筛选,基于2020年医疗器械的相关数据,采用组合赋权法对脆弱性指标赋权,运用云模型方法进行供应链脆弱性评价。评价结果显示,突发公共卫生事件等级是影响医疗器械供应链脆弱性的首要因素,医疗器械短期需求激增是造成供应链脆弱性增加的重要原因,事件冲击使供应链节点间的协同运作失调。因此,需要对突发公共卫生事件切实做好动态监控和管理工作,控制事件影响的时空范围,对需求变异需要建立必要的应急储备,并提高产能储备,建立动态柔性的应急供应链体系,增强供应链协调性。

一种面向空间增材制造的微重力环境地面模拟试验方法

空间增材制造能够将产品全部或部分脱离传统地面制造模式,实现在轨制造或原位制造大型构件。然而,高真空、微重力等复杂特殊的环境使得空间增材制造与地面制造差异很大。为了确保空间增材制造设备的可用性和可靠性,需要在地面环境条件下对微重力环境进行有效模拟。为此,设计一种微重力场的增材制造地面环境模拟试验装置,并开展微重力环境试验研究,对空间增材制造成形工艺过程进行实际模拟与验证。

风速可调的地空一体化风力灭火遥控机结构设计与性能分析

风力灭火遥控机作为地面灭火装备的一种创新形式,具备机动性强、远程操作、快速响应等特点,能够在复杂的火情环境中灵活作业,大大提高了灭火效率和安全性。为探讨风力灭火遥控机在应对森林和草原地表火灾地空一体化监测系统中的角色与作用,对风力灭火遥控机进行结构设计,分析旋转开合结构的安装位置和开口大小对出口风速的影响。利用Fluent软件对风力灭火筒进行流体仿真,结合Design Expert软件对仿真数据进行处理,建立了位置S和开口大小d对出口平均风速和出口最大风速的响应曲面和二次模型。结果表明,安装位置和开口大小均为出口风速的重要影响因素,当风筒入口风速设定为70 m/s、旋转开合结构开口大小为30 mm且安装在位置5处时,出口平均风速和出口最大风速达到最大,分别为97.7551 m/s和290.001 m/s。相较于开口大小,安装位置对出口平均风速和出口最大风速的影响更大,且安装位置越靠近风筒出口处风力灭火机的灭火性能越好。

面向航空风洞地面效应模拟的高速移动带地板装置的设计

研究飞行器在运行过程中的地面效应对其研制具有重要意义。目前国内广泛采用固定地板模拟技术,而黏性附面层的存在导致风洞模拟试验与真实情况严重不符。为此,研制了一种4.0 m×3.4 m的大幅面高速移动带地板模拟装置。采用单电机驱动的主从动辊带动移动带,使其上表面的线速度与风洞来流速度一致,从而消除附面层,准确模拟地面效应。提出了大长径比主从动辊分段加工方法,并采用过盈装配连接方式实现外筒与芯轴的连接,避免了常规焊接手段引起的热变形,显著减小了移动带在高速运行下的不平衡量;设计了快速伺服纠偏系统,使移动带偏移量保持在5 mm以内,并结合分布式控制系统,实现了移动带地板装置各系统的稳定运行;在地面测试中,移动带线速度可稳定在54 m/s左右,速度误差为0.25%左右,且移动带整体振动量抑制在0.1 mm左右。所研制的移动带地板装置成为国内最大的地面效应模拟装备之一,在风洞地面效应模拟与测试中具有广阔的应用前景。

无碰撞磁场重联地面实验平台的研制与建设

中国科学技术大学无碰撞磁场重联实验平台(KRX)是以揭示无碰撞磁场重联的触发机制、对无碰撞磁场重联电子扩散区的结构及相关等离子体波动进行深入细致研究为目标而建设的大型等离子体装置,是开展空间环境基本物理过程地面实验模拟的综合性平台.装置主体为直线位形,真空室直径3 m,由多段拼接而成,整体呈胶囊型,内部采用2 m×1 m全球最大氧化物阴极源产生均匀的背景等离子体.装置外部环绕10组导向场磁线圈,内部由上下两块平行电流板通同向脉冲电流构建重联磁场位形,脉冲电源采用“H”桥结构实现了可控的变速率重联驱动.在装置四周共开设200多个真空窗口,能够通过探针阵列及太赫兹偏振干涉仪、激光诱导荧光等先进光学诊断系统对磁场重联过程开展全域、主动、高精度的测量.该平台是最新一代磁场重联实验平台,其重联区域尺寸达到10倍离子惯性长度,伦德奎斯特数S有望达到105,为开展无碰撞磁场重联实验创造了良好条件,能够对磁场重联过程开展多尺度、全面细致的研究,是卫星观测和数值模拟研究重要补充.目前,实验平台已完成基础建设以及诊断等关键组件的研制,并在小型装置预研结果的基础上完善了针对多尺度、多磁岛合并、三维磁场重联等热点问题的研究方案.

多设备环境下Z世代对公共数字文化移动服务平台使用意愿影响因素的扎根分析

面向国家文化数字化战略,本文将探究Z世代在多设备环境下使用公共数字文化移动服务平台的使用意愿机制,旨在促进我国数字文化的全面发展。以个人发展与数字化时代紧密结合的Z世代为研究对象,以故宫博物院为公共数字文化移动服务平台为代表,从用户视角出发,运用扎根理论分析方法构建影响机制模型。Z世代作为数字化时代的核心群体,对多设备多类型的公共数字文化移动服务平台拥有出色的适应性。针对这一特定人群的研究,不仅有助于推动我国文化的现代化进程,还能为公共数字文化移动服务平台提供定向的优化策略,进一步加强Z世代的文化认同感。

Economic Analysis of using Above Ground Gas Storage Devices for Compressed Air Energy Storage System

Above ground gas storage devices for compressed air energy storage(CAES) have three types:air storage tanks,gas cylinders,and gas storage pipelines.A cost model of these gas storage devices is established on the basis of whole life cycle cost(LCC) analysis.The optimum parameters of the three types are determined by calculating the theoretical metallic raw material consumption of these three devices and considering the difficulties in manufacture and the influence of gas storage device number.The LCCs of the three types are comprehensively analyzed and compared.The result reveal that the cost of the gas storage pipeline type is lower than that of the other two types.This study may serve as a reference for designing large-scale CAES systems.

手机直连卫星技术发展综述

为满足下一代移动通信空、天、地一体全球无缝覆盖,随时随地安全可靠人、机、物无限连接的需求,星地一体融合组网技术成为第6代移动通信技术(6th-Generation Mobile Communication Technology,6G)潜在关键技术之一。其中,如何实现手机直接通过卫星进行通信成为产、学、研界关注的焦点。探讨了手机直连卫星面临的挑战及不同模式,介绍了相关商业项目进展,总结了目前需关注的问题,并为我国手机直连卫星产业的发展提出了相关启示建议。