±500kV直流劣化绝缘子的检测方法研究

主要研究±500kV直流输电线路劣化绝缘子的带电检测方法.分析了应用分布电压测量法、声波测量法、红外测温法、电场检测法和憎水性分级法检测复合绝缘子时的效果,并指出在直流复合绝缘子异常发热测量、直流电场测量和憎水性测量等方面仍需深入研究.     

复合绝缘子积污特性及其灰色预测方法研究

复合绝缘子由于具有优异的憎水恢复和迁移性能,在防污闪方面发挥了巨大的作用,但在污秽、紫外辐射、放电、温湿度等现场复杂因素的长期作用下,复合绝缘子硅橡胶绝缘材料逐渐老化,而老化后的复合绝缘子积污性能却有待验证。因此,展开了老化复合绝缘子积污特性与预测研究。首先,以新型与老化、大伞与小伞型组合的4类绝缘子为样品,开展了10期自然积污试验。通过试验结果,分析了每一类复合绝缘子的积污特性,研究发现：运行了10年的老化复合绝缘子表面盐密大于新复合绝缘子,以大伞型复合绝缘子的第10期盐密为例,老化复合绝缘子表面污秽度比新复合绝缘子表面污秽度增加了0.022 9 mg/cm²,增加率为39.41%。此外,大伞型复合绝缘子表面污秽度大于小伞型复合绝缘子。最后根据灰色理论的原理,建立老化复合绝缘子积污预测模型,模型预测结果与试验结果吻合度较高。     

接触网绝缘子泄漏电流在线监测装置设计

为有效地预测接触网绝缘子污秽水平,提高接触网运行安全可靠性,设计了一种基于ARM的接触网绝缘子泄露电流在线监测装置。通过传感器采集泄露电流和环境湿度预测绝缘子污秽水平,从而判断绝缘子是否应该进行清洗。选取了FQBJ—25/8—760P复合绝缘子为研究对象,在饱和空气湿度下,利用在线监测装置进行人工污秽实验。利用实验数据拟合污秽水平与泄漏电流的关系曲线,为确定接触网绝缘子泄漏电流在线监测装置的预警值提供指导。基于污闪发展三区段思想,提出接触网绝缘子安全运行区、污秽清理区及危险区。     

基于同态滤波和遗传阈值的憎水性自动检测方法研究

首先采用基于同态滤波技术的局部直方图均衡化算法和自适应中值滤波算法消除复合绝缘子憎水性图像的高频噪声。其次,鉴于憎水性图像中水珠引起的反光和透明等干扰,采用最大类间方差作为目标函数和遗传算法作为阈值的优化算法,获取了良好的分割效果。最后,将最大水珠区域的图像的面积比、形状因子、伸长度、7个不变矩共10个特征参数输入BP神经网络,对7个憎水性等级进行判定,结果表明训练准确率和测试准确率分别高达94%和90%。     

基于图像形态特征的复合绝缘子憎水性图像分割算法的研究

对憎水性图像在图像处理中的图像分割环节进行研究。在图像分割处理过程中,因绝缘子等级HC1与其他等级图像的形态特征的不同,导致在实际处理图像时,同一算法不能适用于所有等级的图像。将HC1等级的图像同HC2-HC7等级的图像分开处理,分别采用不同的形态学操作,再利用改进的遗传算法进行图像分割,最终得到准确的图像分割效果图。为复合绝缘子憎水性等级的准确判断提供条件。     

绝缘子在偏心冲洗时有效冲洗面积的研究

带电水冲洗在绝缘子的清洗作业中得到了大量的运用,因此进行带电水冲洗的相关研究就显得十分必要。论文通过理论分析计算出颗粒脱附所需的临界速率,利用fluent对绝缘子在小水、中水、大水的冲洗方式下的偏心冲洗进行三维仿真计算,根据仿真所得到的绝缘子表面的剪切应力云图,对比绝缘子在不同压力、不同的水平偏转角以及不同冲洗方式下有效冲洗区域的大小,同时对比了在相同压力下有效面积与流量的比值,以此来比较水的利用率。结果表明:利用小水和中水的冲洗方式对绝缘子壁面进行冲洗时,随着喷嘴水平偏转角度的增大,有效冲洗面积先增大然后减小;且随着压力的增大,有效冲洗面积的随偏转角度变化的转折点更靠近小的水平偏转角度;而大水冲洗方式下有效冲洗面随着水平偏转角度的增大而持续减少。     

科氏流量计故障检测数据清洗方法研究

科里奥利质量流量计(简称科氏流量计)是一种直接式质量流量测量仪表，可以同时测量流体的质量流量、密度等参数。科氏流量计在使用过程中易出现挂壁故障，影响测量精度，因此，需要对挂壁故障进行定期检测。检测所采集的数据质量会影响科氏流量计挂壁故障检测的精度，针对此问题，必须对脏数据进行清洗，进一步提高科氏流量计挂壁故障检测的准确率，提出了一种基于强化学习的数据清洗算法。将数据与后端机器学习模型相结合，使用Q-Learning算法对数据清洗流程进行搜索，寻找能够使后端机器学习模型达到最佳性能的数据清洗策略。最后对科氏流量计挂壁实验数据进行清洗，对算法进行了验证，检测准确率达92%。实验结果表明，该算法在提高数据清洗效率的同时可以有效提高机器学习模型的性能，使挂壁故障检测准确率得到提高。     

高灵敏度绝缘子电晕放电检测系统研究

绝缘子是电力系统中非常重要的一类电气设备,由于电、热、机械力、污秽的积累等环境因素的作用会使其绝缘性能出现劣化和下降,可能使得绝缘子的表面形成放电,甚至会发生沿面闪络,危害了电力系统的安全;在此基础上提出基于日盲紫外线精确测试紫外线强度的方法,研制了基于日盲紫外线检测技术的绝缘子电晕放电检测装置,通过不同劣化程度和不同污秽条件的盘行悬式瓷绝缘子的实际测试,验证了该装置通过日盲紫外线强度的监测能够定性判断绝缘子的劣化程度和污秽程度,为输电线路绝缘子实时状态监测提供依据.     

芯片表面硅油粘污处理研究

针对芯片表面多余物粘污导致的稳定性和可靠性下降甚至器件失效的问题,对芯片表面典型的表面粘污多余物——硅油展开研究.选取两种型号粘污芯片作为案例,尝试设计一种用以去除芯片表面硅油粘污的清洗方法.使用特定型号UV膜固定芯片,配合有机溶剂异丙醇,使用超声波方法清洗.通过对比实验,确定出去污效果最佳时的超声波功率、频率及清洗时...     

基于3G和嵌入式技术的数据传输系统设计

针对GSM/GPRS网络的数据传输速度和容量的不足,提出了基于3G和嵌入式技术的复合绝缘子远程监控系统的数据传输系统设计。该方案采用OK6410ARM11作为控制器,AD3812_V2作为3G通讯模块。简要介绍了硬件设计、Linux系统制作、Qt移植,重点阐述了基于TCP/IP协议的无线数据传输的实现过程。该方案提高了数据传输的速度和可靠性。相比GSM/GPRS网络,系统有效提高了绝缘子憎水性检测的精度与效率。     

Water droplet properties on periodically structured superhydrophobic surfaces: a lattice Boltzmann approach to multiphase flows with high water/air density ratio

Surface roughness affects the contact angle (CA) due to the increased area of solid–liquid interface and due to the effect of sharp edges of rough surfaces. Roughness may also lead to another non-wetting regime, by forming a composite solid–liquid–air interface between the water and the textured surface; this composite interface exhibits strong water repellency due to the various pockets of air entrapped between the surface textures. The contact between water and a hydrophobic textured surface leads to one of these two regimes depending on the thermodynamics stability of the regimes. In this study, the projection method of lattice Boltzmann method is used to analyze the large density difference at the air and water interface. The method is applied to simulate two-phase flows with the density ratio of up to 1,000. A numerical model is presented to provide a relationship between roughness and CA, which is used to develop optimized texture topography and create a biomimetic superhydrophobic surface. The numerical models encompass the effects of contact area, solid–liquid–gas composite interface and shape edges. The models are reused to analyze different possible roughness distributions and to calculate the effect of the cross-sectional area of pillars, including rectangular, triangular, cross, and pyramidal pillars. The energy barrier is investigated to predict the position of the transition between the Cassie and Wenzel regime observed for each roughness parameter as well as a theoretical free surface energy model.     

Design, fabrication, and testing of micromachined silicone rubbermembrane valves

Technologies for fabricating silicone rubber membranes and integrating them with other processes on silicon wafers have been developed. Silicone rubber has been found to have exceptional mechanical properties including low modulus, high elongation, and good sealing. Thermopneumatically actuated, normally open, silicone rubber membrane valves with optimized components have been designed, fabricated, and tested. Suspended silicon nitride membrane heaters have been developed for low-power thermopneumatic actuation. Composite silicone rubber on Parylene valve membranes have been shown to have low permeability and modulus. Also, novel valve seats were designed to improve sealing in the presence of particles. The valves have been extensively characterized with respect to power consumption versus flow rate and transient response. Low power consumption, high flow rate, and high pressure have been demonstrated. For example, less than 40 mW is required to switch a 1-slpm nitrogen flow at 33 psi. Water requires dose to 100 mW due to the cooling effect of the liquid     

Instability of stagnation line icing

A high Reynolds number analysis is used to investigate the stability of an ice surface lying beneath a low Mach number stagnation-line air flow. The ice surface is covered by a thin water film, whose thickness is consistent with the water mass densities typically encountered in aircraft icing cloud conditions. A multiple scales stability analysis is used to show that the ice surface can become unstable near the stagnation line. The ice surface is found to admit strongly three-dimensional linear instabilities, and increasing the Mach number suppresses the instability.     

Lattice Boltzmann simulation of water and gas flow in porous gas diffusion layers in fuel cells reconstructed from micro-tomography

The porous gas diffusion layers (GDLs) are key components in hydrogen fuel cells. During their operation the cells produce water at the cathode, and to avoid flooding, the water has to be removed out of the cells. How to manage the water is therefore an important issue in fuel cell design. In this paper we investigated water flow in the GDLs using a combination of the lattice Boltzmann method and X-ray computed tomography at the micron scale. Water flow in the GDL depends on water–air surface tension and hydrophobicity. To correctly represent the water–gas surface tension, the formations of water droplets in air were simulated, and the water–gas surface tension was obtained by fitting the simulated results to the Young–Laplace formula. The hydrophobicity is represented by the water–gas-fabric contact angle. For a given water–gas surface tension the value of the contact angle was determined by simulating the formations of water droplets on a solid surface with different hydrophobicity. We then applied the model to simulate water intrusion into initially dry GDLs driven by a pressure gradient in attempts to understand the impact of hydrophobicity on water distribution in the GDLs. The structures of the GDL were acquired by X-ray micro-tomography at a resolution of 1.7 microns. The simulated results revealed that with an increase in hydrophobicity, water transport in GDLs changes from piston-flow to channelled flow.     

基于CFD的绝缘子水冲洗临界水平偏转角研究

利用流体仿真软件fluent对绝缘子冲洗过程中存在的非轴心射流工况进行仿真模拟,分析了水射流以不同水平偏转角对绝缘子进行冲洗时的压力大小以及作用范围;通过Matlab对相同射流压力以及喷管直径在不同水平偏转角时所得到的打击力进行曲线拟合,从而找到在该压力下的临界水平偏转角,对不同压力下临界水平偏转角的大小进行了对比,并利用Matlab的cftool对不同压力和不同喷口直径下的临界水平偏转角度进行了多项式拟合,根据该多项式可以计算出压力在1MPa~4MPa,喷口直径在3mm~8mm任一工况下的临界偏转角度。结果表明:临界偏转角度随着入口压力的增大而减小,其变化率随喷口直径的增大而增大;当入口压力大小相同时,临界偏转角度随喷口直径的增大而减小,为绝缘子的实际清洗工作提供了一定的理论参考。     

机电一体化茶青超声波清洗机的设计开发

介绍了一种基于PIC单片机控制的超声波茶青清洗设备，给出了系统及结构的设计、单片机控制电路和功率放大电路的设计，并较详细地阐述了几种换能器的性能比较和控制器的工作原理及结构，使其具有（超声波加气泡发生器）的恒功率清洗功能，满足了茶青表面杂质清洗及去除农残的要求。经试验证明：超声波清洗速度快、效果好、容易实现工业控制，能保持恒定输出功率，且可以方便地调节。     

一种太阳能光伏板智能吸储装置的研究及应用

随着现代社会对清洁能源的重视程度日益增加,光伏电站的建设速度与规模也日益增长。但光伏板暴露在露天环境中,在清洁过程中存在清洁难度大、消耗水量较大、清洁效果不理想等问题。为实现对露天光伏板的维护,该文设计制作了一种清扫光伏板的装置,其优点是功耗低、小巧灵活、稳定性好,使用无水清洁的方式,克服了光伏电站水资源匮乏、用水困难的问题。该文分两部分介绍该装置:清扫吸储装置的机械结构设计及控制方法的阐述;对实验后的结果进行建模分析,验证了该装置清洁效果的可靠性。