局部放电产生原因及分析

对电力变压器局部放电产生原因进行了分析．并提出了一些具体的处理方法。     

电力变压器局部放电检测方法探讨

首先介绍了电力变压器局部放电产生的典型结构，然后重点分析了电力变压器局部放电的电检测方法和非电检测方法。     

110kV电力变压器局部放电试验及实例分析

首先介绍了110 kV电力变压器局部放电试验的方法、试验电源及其容量的选择、试验接线,进而指出了局部放电试验的干扰及抑制措施,最后以实例说明了局部放电试验在电力变压器绝缘缺陷检测中的广阔应用前景。     

树脂绝缘干式变压器局部放电的测量与判别

介绍了树脂绝缘干式变压器局部放电产生的原因及类型，局部放电量测量系统的建立，以及局部放电类型和位置的简单判别方法。     

树脂绝缘干式电力变压器的局部放电及测量

分析树脂绝缘干式电力变压器局部放电的产生原理和局部放电测量。     

电力变压器局部放电超宽带射频定位研究

采用超宽带射频定位检测技术,并结合变压器结构的特点以及局部放电产生的超宽带电磁波信号在变压器内的传播特性对变压器局部放电进行定位研究。     

高电压环氧树脂浇注电力变压器局放分析与改善

为提高高电压环氧树脂浇注电力变压器在长期运行时的可靠性,通过对影响变压器长期运行可靠性的绝缘介质局部放电产生原理进行分析,以及对不同结构多种产品的局部放电进行测试、分析,提出了产生局部放电的主要原因,阐述了改善的方法和应用效果。     

特高压换流变压器局部放电故障现场定位诊断实例

简要介绍了变压器局部放电故障处理方法,针对两台油色谱分析中乙炔气体超标的±800 kV换流变压器,采用局部放电超声定位检测的方法,准确确定了放电点位置,在随后的内检过程中发现了明显的放电痕迹,验证了超声定位的准确性。该故障定位方法有助于提高变压器维修效率,缩短维修工期。     

智能化电力变压器局部放电超声定位仪

东南大学研制成功电力变压器局部放电超声定位仪。该仪器由微机和传感器等部分组成,属超高压变压器机电一体化产品。在微机控制下,能自动测出绝缘局部放电故障,并可加以定位,能对５００ＰＣ（微微库仑）放电量的局部放电故障（２００ｍｍ的空间球）进行定位。监测精度高,使用方便,实现带电在线检测,无损检测不影响用电,可对２２０ｋＶ或２２０ｋＶ以上电力变压器（容量）的超国家标准的局部放电故障进行超声检测、定位,还可加以变换对大型发电机、电力电缆等局部放电故障进行检测。定位。智能化电力变压器局部放电超声定位仪@李相…     

变压器局部放电超高频在线检测

变压器安全运行对电厂至关重要,对其局部放电在线检测一直是研究的重点。超高频检测法具有强抗电磁干扰能力、频带高、高灵敏度等优点,目前已经广泛被应用。文中重点介绍了变压器局部放电超高频在线检测的原理、超高频局部放电检测系统的构成及各环节的功能,通过举例,从不同角度分析了在线检测信号放电。     

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...