基于Bayes推断的交流接触器剩余电寿命预测

针对交流接触器可靠性开展研究,首先分析交流接触器的电弧侵蚀机理,建立了计及电弧电压及电弧重燃影响的电弧侵蚀模型,根据该模型仿真得到的交流接触器性能退化特征参量变化过程与交流接触器的实际退化规律一致。分析不同工况下性能退化数据特征,提出了不同工况下先验信息的等效折算方法,解决了不同工况下的先验信息利用问题。建立了基于Bayes推断的交流接触器剩余电寿命预测模型,提高了剩余电寿命预测精度,实现了利用不同工况下性能退化数据对交流接触器进行剩余电寿命预测。在AC-4、AC-3两种工况下进行了交流接触器电寿命仿真分析及实验分析,相对误差均小于5.5%,验证了方法的准确性。

交流接触器剩余电寿命智能预测方法的研究

由于在许多重要的行业中均广泛采用了交流接触器,其运行状态的优劣将直接影响电力系统的可靠性、自适应能力和工业生产的安全性。通过对BP神经网络进行改进,以达到对交流接触器剩余电寿命的精确预测。首先,根据现场的生产资料,确定BP神经网络输入,然后利用萤火虫算法求解最优化的权重和阀值,最终得到交流接触器的剩余电寿命。通过MATLAB模拟试验,证明用此方法优化后的BP神经网络具有比传统BP神经网络更低的错误率和更精确的优点,对实际生产中的接触器剩余电寿命预测问题有较好的指导意义。

时间谱电阻率法中的剩余电磁效应研究

根据频谱激电(SIP)法或复电阻率(CR)法中研究剩余电磁(REM)效应的思想,通过分析时间谱电阻率(TSR)法中场的基本特征,在TSR法中建立了与SIP(或CR)法中参数φmax φ0max相类似的参数———Emax E0,用来描述TSR法中的REM效应。通过对一维可极化大地模型的REM效应的理论计算,验证了用Emax E0表示的REM异常可用来形象地反映地电断面电阻率的高低。

变应力条件下低压断路器剩余电寿命预测

低压断路器开断过程中电弧对触头的侵蚀是引起触头系统失效的主要原因,实际服役过程中低压断路器承受的电流应力是不断变化的,电流应力不同电弧侵蚀程度也不同。该文研究触头质量损失和燃弧特征量(电弧电量、焦耳积分和燃弧能量)的关系,根据不同的电弧侵蚀机理划分电流范围,利用分段函数描述电弧侵蚀因子与电流应力的关系,建立不同电流范围内电弧侵蚀因子数学模型;利用分段函数描述平均触头质量损失率与电流应力的关系,建立不同电流范围内平均触头质量损失率数学模型;根据不同的现场信息,提出3种变应力条件下低压断路器的剩余电寿命预测方法;通过不同电流应力下电寿命试验来模拟低压断路器触头系统的性能变化,由先验信息确定预测模型参数,并对同批次低压断路器进行变应力条件下电寿命验证试验,证明剩余电寿命预测模型的准确性,为低压断路器可靠性评估提供理论基础。

投切电抗器/电容器用断路器剩余电寿命预警系统

量化剩余电寿命是断路器寿命评价的关键。在研究断路器开断过程和电弧能量累积加权法的基础上,研究断路器剩余电寿命预警系统拓扑结构,深入讨论了采集单元的硬件原理和工作逻辑、合并单元通信方式、上位机软件功能和系统运行流程。研发了投切电抗器/电容器用断路器剩余电寿命预警系统,并部署在某110 k V变电站,不仅能记录断路器开断电流的波形,还能根据剩余电寿命阈值发出告警提示,预测剩余电寿命发展趋势,为断路器管理维护提供辅助决策。

电磁继电器剩余电寿命智能预测研究

针对以往继电器剩余电寿命实际预测方法存在的不足,建立一种用于电磁继电器剩余电寿命预测的BP神经网络模型,该模型采取继电器的吸合时间和超程时间作为输入量,继电器剩余电寿命作为输出量,通过粒子群-蛙跳算法优化网络结构初始参数,利用改进BP算法训练BP神经网络,并加以测试验证。实验结果表明,经过粒子群-蛙跳算法优化的BP神经网络模型能快速、准确地实现电磁继电器剩余电寿命预测。

基于马尔科夫链理论的电动汽车充电负荷度量研究

电动汽车充电负荷度量是电动汽车充电配置规划的重要依据,但现行方法的度量精度较低,度量结果的置信水平较低,MPE较高,无法达到预期的度量效果,因此,提出基于马尔科夫链理论的电动汽车充电负荷度量研究。利用马尔科夫链理论对电动汽车充电和出行过程进行表达,描述汽车剩余荷电状态转移过程,并根据不同时间段的荷电状态转移过程分析电动汽车充电负荷需求,度量电动汽车充电负荷,实现基于马尔科夫链理论的电动汽车充电负荷度量。经证明,该设计方法度量结果的置信水平在96%以上,MPE不超过1%,可以实现对电动汽车充电负荷的精准度量。

绝缘电阻的测量及影响绝缘电阻的主要因素

文章介绍了绝缘电阻测量方法 ,并详细地分析了影响电气设备绝缘电阻测量结果的几个主要因素 。

采用太阳能的电气化铁路

萨克森瑞士的Kimitzschtal米轨铁路是欧洲第一条采用太阳能的电气化铁路。这条用于旅游业的铁路在联邦研究技术部长的帮助下获得了一个带有756块太阳能板的光电设备,该756块太阳能板布置在面积为325m^2的屋顶上,功率达40kW,每年根据气候的不同约能生产3万kWh的电能。该铁路由此可获得其耗能的40％,机车车辆及铁路装备没能利用的剩余电能可送入商业电网。

Development of Management Systems for Electric Vehicle Battery Series

A kind of management system for electric vehicle (EV) battery series was developed. The system can predict residual capacity for EV battery series and mileages. The system can determine if it is necessary for the battery series to be charged. The system can determine which battery is necessary to be updated for the reason of damage or aging. The system can display the total voltage of battery series, extreme voltage and temperature of every battery in the series. The system can display the accumulative discharge for every battery in the series. The system can alarm when both total or extreme voltage is at low level, or temperature of a battery in the series is at high level. The system provided with a microprocessor as key part can collect and record signal of charging and discharging current, total voltage, extreme voltage and temperature for every battery. The mathematical model of residual capacity for EV lead acid batteries was discussed in details. The system operates well in the laboratory and meets the requirement.

Battery Management System with State ofCharge Indicator for Electric Vehicles

Aim To research and develop a battery management system(BMS)with the state of charge(SOC)indicator for electric vehicles (EVs).Methods On the basis of analyzing the electro-chemical characteristics of lead-acid. battery, the state of charge indicator for lead-acid battery was developed by means of an algorithm based on combination of ampere-hour, Peukert's equation and open-voltage method with the compensation of temperature,aging,self- discharging,etc..Results The BMS based on this method can attain an accurate surplus capa- city whose error is less than 5% in static experiments.It is proved by experiments that the BMS is reliable and can give the driver an accurate surplus capacity,precisely monitor the individual battery modules as the same time,even detect and warn the problems early,and so on. Conclusion A BMS can make the energy of the storage batteries used efficiently, develop the batteries cycle life,and increase the driving distance of EVs.

Effects of Oxygen Vacancy on the Adsorption of Formaldehyde on Rutile TiO2（110） Surface

Oxygen vacancy （Ov） has significant influence on physical and chemical properties of TiO2 systems, especially on surface catalytic processes. In this work, we investigate the effects of Ov on the adsorption of formaldehyde （HCHO） on TiO2（110） surfaces through first- principles calculations. With the existence of Ov, we find the spatial distribution of surface excess charge can change the relative stability of various adsorption configurations. In this case, the bidentate adsorption at five-coordinated Ti （Tisc） can be less stable than the monodentate adsorption. And HCHO adsorbed in Ov becomes the most stable structure. These results are in good agreement with experimental observations, which reconcile the long-standing deviation between the theoretical prediction and experimental results. This work brings insights into how the excess charge affects the molecule adsorption on metal oxide surface.

Numerical study of the tides and residual currents in the Qiongzhou Strait

Based on the three-dimensional ECOM model,the tide,tide-induced residual current,wind-driven and density currents in the Beibu (Tonkin) Gulf and Qiongzhou Strait are diagnostically computed in fine grid.The tides and tidal currents in the Beibu Gulf and Qiongzhou Strait are well reproduced.The model results show that the semidiurnal tidal wave propagates eastward from the Beibu Gulf through Qiongzhou Strait,while diurnal tidal waves enter the strait from both the eastern and western sides and interact on the southeast coast of the strait.The formation processes of the residual currents in Qiongzhou Strait in summer (August) and winter (January) are mainly discussed.It is shown that the total residual currents (coupling effect of wind,tide and density) in the strait are westward in both summer and winter.The water volume transported from the east to west into the Beibu Gulf is 0.026 Sv in summer and 0.116 Sv in winter.Numerical experiments indicate that the dominant factor affecting the residual currents in the strait is not the wind stress but the tidal rectification.The westward tide-induced residual current,driven by the tidal rectification,is rather strong in the strait with water volume transport of 0.063 Sv.The wind in summer only reduces the westward tide-induced residual current to a certain extent,and the wind in winter approximately doubles the westward tide-induced residual current through the strait.The density current contributes little to the total residual current in both summer and winter.

A model study of residual oil distribution jointly using crosswell and borehole-surface electric potential methods

Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide enough range but its resolution is limited, particularly for reservoirs with complex oil and water distribution or complicated structure. In this study, we attempt to accurately locate the 3-D reservoir water and oil distribution by combining borehole-surface and crosswell electric potentials. First, the distributions of oil and water in both vertical and horizontal directions are detected by the borehole-surface and erosswell electric potential methods, respectively, and then the measured crosswell potential result is used to calibrate the measured borehole-surface electric potential data to improve vertical resolution so that the residual oil distribution is determined in a lower half-space with three dimensions. The evaluation of residual oil distribution is obtained by investigation of differences between the simulation results of the reservoir with and without water flooding. The finite difference numerical simulation results prove that the spatial residual oil distribution can be effectively determined by combining the crosswell and borehole-surface electric potentials.

Bottom Currents Observed in and Around a Submarine Valley on the Continental Slope of the Northern South China Sea

Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observations reveal that bottom currents are strongly influenced by the topography, being along valley axis or isobaths. Power density spectrum analysis shows that all the currents have significant peaks at diurnal and semi-diurnal frequencies. Diurnal energy is dominant at the open slope site, which is consistent with many previous studies. However, at the site inside the valley the semi-diurnal energy dominates, although the distance between the two sites of observation is quite small （11 kin） compared to a typical horizontal first-mode internal tide wavelength （200 km）. We found this phenomenon is caused by the focusing of internal waves of certain frequencies in the valley. The inertial peak is found only at the open slope site in the first deployment but missing at the inside valley site and the rest of the de- ployments. Monthly averaged residual currents reveal that the near-bottom currents on the slope flow southwestward throughout the year except in August and September, 2013, from which we speculate that this is a result of the interaction between a mesoscale eddy and the canyon/sag topography. Currents inside the valley within about 10mab basically flow along slope and in the layers above the 10mab the currents are northwestward, that is, from the deep ocean to the shelf. The monthly mean current vectors manifest an Ek- man layer-like vertical structure at both sites, which rotate counter-clockwise looking from above.

Observed residual currents off the Changjiang (Yangtze) River mouth in wintertime of 1959 and 1982

Data taken in the two large-scale ocean investigations in China in winter 1959 and 1982 are used to analyze the residual current off the Changjiang (Yangtze) River mouth in this paper. The current in wintertime off the river mouth consist of the Changjiang runoff, wind-driven current, coastal current, density-driven current and Taiwan Warm Current (TWC). The TWC occurs in wintertime off the mouth. The surface TWC reaches only to the east side of Dinghai, then turns southeastward. The bottom TWC can flow to the area off the Changjiang mouth along west slop of the submerged river valley (SRV) and to the area off the Subei coast. The simulated currents by 3D model are basically consistent with the observed currents, although the model was run with climatological forces and the observations was done in episodic time manner.

Observed residual currents off the Changjiang (Yangtze) River mouth in summertime of 1959 and 1982

Data taken in two large scale ocean observations in China in summer 1959 and 1982 were used to analyze the residual current off the Changjiang (Yangtze) River mouth. The currents at surface off the mouth in July 1959 and 1982 flow northeastward and eastward due to the river discharge, the current speed was larger in1982 than in 1959. All the bottom currents flow landward due to baroclinic effect. The surface current was controlled by the river runoff and the Taiwan Warm Current (TWC). A return current at surface off the mouth was observed in September 1959. In general, the bottom currents were controlled by the TWC in most study area in addition to the runoff near the mouth. Although driven by 3-D model with the monthly averaged forces (river discharge, wind stress, baroclinic effect, open boundary water volume flux and tidal mixing) in August, the simulated circulations were basically consistent with the observed ones with episodic time manner.

Life prediction of Ni-Cd battery based on linearWiener process

Predicting the life of Ni-Cd battery for electric multiple units(EMU)can not only improve the safety and reliability of battery,but also reduce the operating costs of EMU.For this reason,a life prediction method based on linear Wiener process is proposed,which is suitable for both monotonic and non-monotonic degraded systems with accurate results.Firstly,a unary linear Wiener degradation model is established,and the parameters of the model are estimated by using the expectation-maximization algorithm(EM).With the established model,the remaining useful life(RUL)of Ni Cd battery and its distribution are obtained.Then based on the unary Wiener process degradation model,the correlation between capacity and energy is analyzed through Copula function to build a binary linear Wiener degradation model,where its parameters are estimated using Markov Chain Monte Carlo(MCMC)method.Finally,according to the binary Wiener process model,the battery RUL and its distribution are acquired.The experimental results show that the binary linear Wiener degradation model based on capacity and energy possesses higher accuracy than the unary linear wiener process degradation model.

Residual current compensation for single-phase grounding fault in coal mine power network

The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.

Evolution of Surface Cold Patches in the North Yellow Sea Based on Satellite SST Data

Ten years （from 2005 to 2014） of satellite sea surface temperature （SST） data from the Advanced Very High Resolution Radiometer （AVHRR） are analyzed to reveal the monthly changes in surface cold patches （SCPs） in the main areas of the Northern Yellow Sea （NYS）. The Canny edge detection algorithm is used to identify the edges of the patches. The monthly changes are de- scribed in terms of location, temperature and area. The inter-annual variations, including changes in the location and area of the SCPs from 2010 to 2014, are briefly discussed. The formation mechanisms of the SCPs in different periods are systematically analyzed using both in situ data and numerical simulation. The results show that from May to October, the location and area of the SCPs re- main stable, with a north-south orientation. The SCPs altogether cover about I° of longitude （124°E-125°E） in width and 2° of lati- tude （37.5°N-39.5°N） in length. In November, the SCP separates from the Jangsan Cape and forms a closed, isolated, and approxi- mately circular cold patch in the central NYS. From May to October, the upweUing that leads to the formation of the SCP is mainly triggered by the headland residual current, wind field, climbing movement of the current and secondary circulation at the tide front. In November, cyclonic circulation in the NYS is primarily responsible for generating the upwelling that leads to the formation of the closed and isolated SCE