漏电保护器误跳闸现象分析

应用漏电保护器的工作原理分析了实践中遇到的两个由于接线错误导致漏电保护器跳闸现象。加深了对零序电流互感器和漏电保护器的理解;介绍了在实际接线中应该注意那些问题,以避免此类现象的出现。     

三相不平衡对剩余电流保护器误动的影响分析

剩余电流保护器是低压系统保障人身以及设备安全的重要设备，但是谐波、三相不平衡等因素会导致剩余电流保护器发生频繁误动，甚至使其无法投入使用。针对低压配电网三相不平衡系统，综合考虑三相线路阻抗、漏阻抗及负载的不平衡情况，建立了三相不平衡系统漏电流仿真模型，然后在多种不平衡程度及负荷水平下，对系统的漏电流进行了仿真分析。结果表明，在三相线路阻抗或漏阻抗不平衡下，系统的漏电流很小；在三相负荷不平衡的情况下，系统的漏电流较大，且负荷水平及负荷不平衡度越高，漏电流越大。因此，负荷水平及负荷不平衡度是剩余电流保护器频繁误动原因之一。     

微机保护测量电流回路的故障分析及改进方法

针对实际工程应用中,由于电流回路的接线错误造成微机保护的功能不能实现或者测量错误,提出基于微机保护和测量仪表的电流回路接线错误自动识别及自适应电流回路接线方法。     

基于机器学习的用户侧异常数据诊断研究

考虑到大数据用户侧数据可能出现的异常情况，提出了以机器学习为支撑的异常数据诊断分析框架。本文首先基于用户侧数据分类，建立了包含用电特征、情境特征、环境特征和台区特征的数据模型。然后，从单个用户数据异常和台区数据异常角度详细分析用户侧数据异常的原因，据此建立数据异常故障模式和数据异常特征之间的关系以及用户侧异常数据分析框架。针对最为关键的电能数据异常诊断难题，提出负荷回归分析预测、基于神经网络的负荷预测、聚类分析和基于投影方法四种无监督学习在线异常检测方法，并通过算例对比分析了四种方法有效性和准确性。     

基于电气特性分析的台区拓扑变化辨识方法

低压台区拓扑关系识别是支撑配电网智能化、数字化的关键基础.当前台区相序识别多从静态识别角度研究,缺少拓扑变化识别方法,就此提出了基于电气特性分析的台区拓扑变化辨识方法.对台区每天的用电数据设置滑动窗口,首先判断每一帧滑动窗口的电流数据的拟合偏差是否超过阈值;然后在拓扑变动较大的情况下直接启动拓扑计算程序,对台区用户重新计算相序拓扑关系,而在拓扑发生小变动的场景下,启动拓扑变动辨识程序,进一步分析了拓扑变动的电气特性并提出辨识方法;最后通过算例表明所提方法可以有效发现并辨识出相序拓扑变化的用户.     

低压电网智能化远程控制系统在山区农村台区的应用

传统的低压台区的总漏电保护器还处于人工管理的落后状态,往往是某一用户的漏电故障造成整个台区大面积停电,抢修队伍有时须夜间奔波十几公里山路赶去排除故障,人工合闸送电,造成停电时间长,用户满意度下降的局面,对抢修人员的人身安全也非常不利。使用了低压电网智能化远程控制系统后,解决了传统总漏电保护器频繁跳闸,复电时间长,配电抢修工作人员频繁出动,疲于奔波的局面,提高了台区供电可靠性的同时又增加了客户的满意度,可谓一举多得。     

TA回路接线错误原因及对策分析

新建或改扩建变电站投运前,模拟负荷通流试验无法正常进行。鉴于此,根据电流互感器接线方式和二次回路要求,在施工现场寻找电流互感器二次回路接线错误原因,制订相应对策,以尽量减少电流互感器二次回路的人为接线错误,确保电流互感器二次回路接线正确。     

浅谈剩余电流动作继电器的原理及应用

剩余电流动作继电器,作为主保护或者后备保护应用在低压配电系统中,主要对于消除对人体的伤害或火灾的隐患起着重要的作用,正确使用剩余电流动作继电器和对其原理的了解,对保障电气系统安全可靠运行具有重大意义。对于TT系统,采用剩余电流动作继电器对接地故障进行保护;而在TN系统中,速断和漏电保护已满足对接地故障保护的灵敏度要求。     

智能低压配网巡检仪的设计与应用

在低压供电系统中,由于电网设施薄弱、家用电器老化及人为用电陋习等原因,低压供电线路漏电故障经常发生,不但造成了能源浪费,而且会导致用电设备损坏,甚至会发生人体触电、引发电器火灾,危害到人们的生命和财产安全。现设计一种智能低压配网巡检仪,能实时监测线路中的漏电流大小,具备漏电流数据记录、漏电流报警阈值设置等功能;当监测到漏电流超限时能主动上报到用户APP,用户也可查询当前、历史漏电流大小;该装置同时具备定位功能,可导航用户到达故障点,及时排查出故障线路,高效便捷。     

基于广域信息处理的井下选择性漏电保护技术

针对煤矿低压电网系统常见的漏电故障及当前漏电保护系统存在的问题,首先分析了漏电事故发生时各支路中零序电压、零序电流等电信号的参数特征,然后对基于广域信息处理的漏电保护系统的工作原理、区域层级划分方法以及漏电保护流程等进行了研究。在此基础上,提出了基于广域信息处理的故障识别和故障区域定位方法,由此可提高煤矿生产的稳定性,降低漏电事故影响范围,给企业带来较大的经济效益。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...