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.

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.

Fault Line Selection Method Considering Grounding Fault Angle for Distribution Network

In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.

Protection of Zero-Sequence Power Variation in Mountain Wind Farm Collector Lines Based on Multi-Mode Grounding

The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.

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.

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。

“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。

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。

多光谱TDICCD航天相机快视一体化地面检测系统设计与实现

针对多光谱时间延迟积分电荷耦合器件(Time Delay Integration Charge Coupled Devices,TDICCD)航天相机的产品研发,提出快视一体化地面检测系统的设计方案,并依托项目实现该设计方案。设计包括主机系统搭建、CXP(CoaXPress)高带宽数传采集卡、测控采集卡、图采测控上位机、光电参数测试、非均匀性校正以及刷新芯片重注等实现。采用一体化设计,所有软硬件全部集成于地检主机系统,方便携带和使用。采用模块化设计方法,使用通用的主机接口,实现多种采集卡在不同主机系统之间交叉使用;使用通用的数据传输接口、RS-422传输接口,使得采集卡不仅适用于本相机的接口协议,也能在修改现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)代码后适用于其他相机。经验证,该地面检测系统能有效完成多光谱TDICCD航天相机的功能测试、光电参数性能测试的要求,为项目顺利进行提供有力保障。

开放式停车泊位地锁锁车装置的结构设计改进

开放式停车泊位智能收费管理系统的泊位地锁主要包括车牌识别装置、车辆检测地磁感应器、锁车装置等组成部分,其中起挡车作用的锁车装置的结构设计直接影响到系统工作的可靠性和耐久性。通过对锁车装置的结构设计不断改进,使其功能不断完善,故障率不断降低,维护保养更加便捷。

采用螺旋状接地模块的接地装置自动化控制

针对接地装置当中电流泄露不足,跨步电压较大以及装设接地装置时间过长的问题,该文提出结合螺旋状接地模块的接地装置自动化控制模型。通过中央控制单元对接地装置进行自动化控制,并结合气动筒调节接地装置的长度;同时通过将螺旋状接地模块代替传统接地模块的接地装置,以提高接地电流的引流以及泄流的水平。经过实验验证,该办法能够使跨步电压降低,同时降低接地装置控制成本。通过工作人员的接地装置装设对比,该文设计接地装置装设简单,极大提高了接地装置的装设效率。

基于可穿戴式步行引导仪的可视化步行训练对帕金森病冻结步态患者步行能力的影响

目的:探讨基于可穿戴式步行引导仪的可视化步行训练对帕金森病冻结步态患者步行能力的影响。方法:选取23例帕金森病冻结步态患者为试验组,同时选取20例性别、年龄等匹配的健康者为对照组。试验组给予利用可穿戴式步行引导仪的可视化步行训练,20min/次,2次/日,训练1周。利用Vicon三维步态分析系统收集试验组训练前后和对照组时空参数、非优势侧及优势侧运动学参数、非优势侧及优势侧地面反作用力参数(包括前-后侧峰值、内-外侧峰值及纵向第一峰值)。结果:(1)训练后,试验组患者步速及双侧步长均明显增加,步频、双支撑期明显减小,与训练前相比,差异均有显著性意义(P<0.05);训练后,试验组患者优势侧步长、步频及双支撑期与对照组比较,差异均无显著性意义(P>0.05)。(2)训练后,试验组患者双侧髋关节着地角度、踝背屈及跖屈最大角度及下肢关节活动范围均明显增加,膝关节着地角度减小,踝关节第一峰值出现的阶段延迟,与训练前相比,差异均有显著性意义(P<0.05);训练后,试验组患者双侧(膝关节着地角度、踝背屈最大角度、踝关节第一峰值出现阶段、下肢关节活动范围)和优势侧(髋关节着地角度、踝跖屈最大角度)与对照组比较,差异均无显著性意义(P>0.05)。(3)干预后,试验组患者双侧地面反作用力前-后侧峰值及纵向第一峰值明显提高,地面反作用力内-外侧峰值明显下降,差异均有显著性意义(P<0.05)。与对照组相比,非优势侧后侧峰值、内侧峰值及优势侧各项参数均无显著性差异(P>0.05)。结论:基于可穿戴式步行引导仪的可视化步行训练可有效提高帕金森病冻结步态患者步行平衡稳定性及步伐连贯性。

新型手抛式输电线路接地线的研究

为适应超特高压输电线的快速发展和检修工作的需要,解决输电耐张塔内转角挂接困难的问题,结合现场工作实际,设计出一种手抛式接地线。对比传统已有的2种接地工具的弊端,提出新型接地线夹结构,通过机械设计连接,在接地线夹领域首次实现单方向受力双段控制线夹完成接地线的远距离抛挂及拆除。通过现场实地1∶1输电塔挂拆试验,顺利完成挂接,经过安全检测后已量产。根据电力生产需要,利用上述机械线夹结构思想,变更相应线夹尺寸、配置不同长度和截面接地铜线,将能应用于多种电压等级的输电线路接地。

航天发射场接地系统模式分析

针对中国各航天发射场地面设施接地系统工程设计与火箭、航天器等地面测试设备的接地要求多年来一直存在模式不统一的问题,结合各航天发射场接地系统多年运行经验,在火箭、航天器等技术调研及现场测试的基础上,对航天发射场接地系统模式进行了深入的技术研究,统一中国航天发射场地面设施接地系统的模式,从根源上解决了困扰多年的发射场接地系统模式不统一的问题。排除其在火箭、航天器测试发射工作中的故障,可进一步提高中国航天发射场接地系统的技术水平。