Characterization of a 3-Phase a.c. Free Burning Arc Plasma

A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed neutral point. This gives rise to a rich and complex phenomenology related to instabilities and arc motion since the arcs are ＂burning＂ freely in the gas flow between the three electrodes. This paper is dedicated to the analysis of the behavior of such a system under typical conditions using argon and nitrogen as plasma gases. A classification of are configuration, arc commutating, arc interaction, arc motion and arc instabilities are discussed based on ultra high-speed cine camera analysis. A simple model describing the time evolution of the system is also presented and compared with the experimental measurements. The results show that an adequate control could allow the improvement of the overall system.

Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low- voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines.

Characteristic Analysis of AC Plasma Arc in Water

An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma are was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 kW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 V to 1300 V, the arc voltage is from 40 V to 100 V, the arc current is from 2 A to 7 A, and the zero rest period is from 1 ms to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.

Effect of Injection Position on In-Flight Melting Behavior of Granular Alkali-Free Glass Raw Material in 12-Phase AC Arc Plasma

An innovative in-flight glass melting technology with a multi-phase AC arc plasma was developed to save energy and reduce emissions for the glass industry. The effect of the injection position on the in-flight melting behavior of granulated powders was investigated. Results show that the injection position has a strong effect on the melting behavior of alkali-free glass raw material. With the increase in injection distance, the vitrification, decomposition, and particle shrinkage of initial powders are improved. Longer injection distance causes much energy to transfer to particles due to a longer residence time of powder in the high temperature zone. The high vitrification and decomposition degrees indicate that the new in-flight melting technology with 12-phase AC arc can substantially reduce the melting and refining time for glass production.

ARC报告说低功率AC驱动器市场将增长

低功率AC驱动器市场正从2009年严重的全球经济衰退中恢复过来，2010年出现反弹。根据ARC咨询集团的一项新研究，新兴经济体在2010年主导了经济的增长，它们还处于预期内的重要市场。低功率AC驱动器市场也将在对能源效率及环境的日益关注的刺激下开始增长。世界主要经济体已经接受了这个事实，即能源的有效利用对全球经济增长和繁荣是必要的。

Quick Surface Treatment of AZ31B by AC Micro-arc Oxidation

In order to explore an effective way to shorten treatment time and enhance the quality of treatment coating, AC micro-arc oxidation was conducted to treat the surface of AZ31 B deformation magnesium alloy in KF＋KOH treatment solution. The infl uences of micro-arc oxidation parameters such as concentration of KF, concentration of KOH, output voltage of booster, temperature of treatment solution, and treatment time on treatment coating thickness were raveled out under different conditions. The structure and composition of treatment coating were determined, the growth mechanism of treatment coating was discussed, and the quick surface treatment technology for compact treatment coating with maximum thickness was developed. The experimental results show that： A maximum 33 μm-thick compact treatment coating, consisting of MgF2 and MgO mainly, can be formed on AZ31 B in 112 s under the conditions of 1 132 g/L KF, 382 g/L KOH, 66 V for output voltage of booster and 34 ℃ of treatment solution which were optimized by a genetic algorithm from the model established by artifi cial neural networks. There are no ＂crater-shaped＂ pores in this treatment coating as the heat shock resulting from the smooth variation of AC sinusoidal voltage is far smaller than that of the rigidly varied DC or pulse current. The treatment time is only one sixth of that adopted in the other surface treatment technology at best, principally for the reason that the coating can always grow irrespective of the electric potential of AZ31 B. This investigation lays a fi rm foundation for the extensive application of magnesium alloy.

AC／DCRP交替MIG焊接方法的研究

介绍ＡＣ／ＤＣＲＰ交替ＭＩＧ焊接方法。它可以显著改善交流ＭＩＧ焊的焊缝成形，同时克服直流ＭＩＧ焊的电弧磁偏吹。利用这种方法还可进一步开发熔深控制功能。

基于ACS-DBN的电弧增材制造焊道尺寸预测

焊道重叠是电弧增材制造(Wire and Arc Additive Manufacturing,WAAM)技术的本质,合适的工艺参数选择对于控制焊道几何形状,提升成型零件的尺寸精度具有重要的意义,为此提出一种基于自适应布谷鸟搜索(Adaptive Cuckoo Search,ACS)算法优化的深度信念网络(Deep Beilef Network,DBN)预测模型ACS-DBN,在给定喷嘴高度、焊接电流、焊接速度、送丝速度这4个工艺参数的基础上预测焊道的熔宽和余高;基于实验法确定最优的隐层层数和隐元数量,构建基于ASC-DBN的WAAM焊道尺寸预测模型;利用仿真实验验证ACS-DBN预测模型的性能,与已有模型对比,结果表明,ACS-DBN模型能有效的映射WAAM焊道尺寸和焊接工艺参数之间的复杂非线关系,控制焊道尺寸的相对误差在6%以内,相对于其他预测模型具有更高的准确性和稳定性。

110～240VAC交流数字信号输入接口电路分析与软件实现

主要是针对110～240 VAC交流信号逻辑输入转化为MCU能识别的逻辑信号,提出一种新的方法,包括:阻容采样,稳压限幅、光电隔离,软件状态机实现。详细介绍此方法实现的原理,着重是对阻容采样和软件状态机的实现方法进行详细的分析。这种方法具有功耗低,抗干扰能力强,可靠性高的特点,符合标准IEC61131-2中的规定,应用广泛。

Catalytic technology for water treatment by micro arc oxidation on Ti-AI alloy

The feasibility of the formation of a liquid plasma catalysis system through micro arc oxidation（MAO） under AC power with titanium-aluminum alloy electrodes was investigated.In the decolorization of organic dyeing wastewater simulated with Rhodamine B,Ti-Al alloy electrodes were superior over Ti electrodes and Al electrodes.The optimal molar percentage of Ti in alloy electrodes was 70%and the optimal decolorization rate was up to 88.9%if the additive suitable for Al was added into the solution to be treated.The decolorization rates were the same in the case of the alloy-alloy electrodes and alloy-Al electrodes.The proportion of the effects of plasma,TiO2 catalyzer during MAO and H2O2 after MAO in decolorization has been obtained.With the catalysis of TiO2 formed on the electrodes,the reaction rate was improved by a maximum of 95%and the decolorization rate was improved by a maximum of 71.6%.Based on the spectral analysis,the plasma catalysis mechanism has been studied.

Sr,Nd,Pb and trace element systematics of the New Caledonia harzburgites:Tracking source depletion and contamination processes in a SSZ setting

The New Caledonia ophiolite(Peridotite Nappe)consists primarily of harzburgites,locally overlain by mafic-ultramafic cumulates,and minor spinel and plagioclase lherzolites.In this study,a comprehensive geochemical data set(major and trace element,Sr-Nd-Pb isotopes)has been obtained on a new set of fresh harzburgites in order to track the processes recorded by this mantle section and its evolution.The studied harzburgites are low-strain tectonites showing porphyroclastic textures,locally grading into protomylonitic textures.They exhibit a refractory nature,as attested by the notable absence of primary clinopyroxene,very high Fo content of olivine(91-93 mol.%),high Mg#of orthopyroxene(0.91-0.93)and high Cr#of spinel(0.44-0.71).The harzburgites are characterised by remarkably low REE concentrations(<0.1 chondritic values)and display"U-shaped"profiles,with steeply sloping HREE(DyN/YbN=0.07-0.16)and fractionated LREE-MREE segments(LaN/SmN=2.1-8.3),in the range of modern fore-arc peridotites.Geochemical modelling shows that the HREE composition of the harzburgites can be reproduced by multi-stage melting including a first phase of melt depletion in dry conditions(15%fractional melting),followed by hydrous melting in a subduction zone setting(up to 15%-18%).However,melting models fail to explain the enrichments observed for some FME(i.e.Ba,Sr,Pb),LREE-MREE and Zr-Hf.These enrichments,coupled with the frequent occurrence of thin,undeformed films of Al2 O3,and CaO-poor orthopyroxene(Al2O3=0.88-1.53 wt.%,CaO=0.31-0.56 wt.%)and clinopyroxene with low Na2 O(0.03-0.16 wt.%),Al2 O3(0.66-1.35 wt.%)and TiO2(0.04-0.10 wt.%)contents,point to FME addition during fluid-assisted melting followed by late stage metasomatism most likely operated by subductionrelated melts with a depleted trace element signature.Nd isotopic ratios range from unradiogenic to radiogenic(-0.80<εNdi≤+13.32)and negatively correlate with Sr isotopes(0.70257≤87Sr/86Sr≤0.70770).Pb isotopes cover a wide range,trending from DMM toward enriched,sediment-like,compositions.We interpret the geochemical signature displayed by the New Caledonia harzburgites as reflecting the evolution of a highly depleted fore-arc mantle wedge variably modified by different fluid and melt inputs during Eocene subduction.

Coupling model of AC filter branch in SF6 circuit breaker during the break process

In this paper, a coupling model of the AC filter branch circuit with the arc plasma in the circuit breaker was built to investigate the arcing process considering the harmonic current. The comparisons among the current at power frequency(50 Hz), power frequency combining the 11 th harmonic and power frequency combining the 24 th harmonic show that the high-order harmonic current would lead to higher decreasing rate of current before current-zero period. In addition, the influence of arc on the amplitude of high-order harmonic current is not negligible. Thus, the coupling of arc with AC filter branch circuit is quite necessary in the numerical modeling of the circuit breaker in the AC filter branch at the high voltage direct current converter station.

Distribution of Partial Arc Propagation Path on Insulator and Its Discrimination Method

Pollution flashover is one of themajor insulation accidents that can occur inmodern power systems.If the local arc is not sufficiently elongated by the creepage distance,the flashover performance of the insulator will decrease.The insulator structure and equivalent salt deposition density(ESDD)are the main factors affecting the arc path and length.To investigate the forms of arc paths under different insulator structures and their influence on flashover characteristics,a platformfor recording arc paths is established.This study presents amethod to identify the pattern and distribution of insulator arc paths based on the effect of initial arc on electric field distribution.The results show that there are two main types of local arc paths between umbrellas—the cling-surface arc and the air-jump arc.Moreover,the air-jump arc includes two types—the bridging arc and the gap arc.With the increase in umbrella spacing and ESDD,the probability of arc propagation along the surface increases.The use of the creepage distance can be improved by changing the creepage coefficient to increase the distance between umbrellas.This method has over 90%accuracy.This study is of great significance for improving insulator structure and reducing pollution flashover accidents.

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。

基于触头燃弧损耗的动车组交流接触器剩余电寿命预测

动车组交流接触器的性能状态与列车运行安全密切相关。针对动车组交流接触器在三相不均匀燃弧损耗工况下,特征参数变化趋势与电寿命趋势的复杂映射关系问题,提出一种基于触头燃弧损耗的电寿命预测方法。首先,基于触点的燃弧机理,分析了导致三相触头之间燃弧损耗差异的原因,并在此基础上进行了随机燃弧损耗和定相燃弧损耗2种模式下的电寿命试验。然后,提取电寿命试验过程中的接触器特征参数,利用Spearman等级相关系数方法计算各特征参数与累积燃弧损耗之间的相关性,以此筛选出相关性强的特征参数构成状态识别的特征参数组。接着通过多元线性回归的方法对特征参数组进行融合,得到表征燃弧损耗状态的指标,对比指标曲线与实际寿命曲线发现试验样本存在初始燃弧损耗量的问题。之后建立基于相似性的接触器剩余燃弧损耗量预测模型,在评估环节引入能将初始燃弧损耗量的不确定性问题转化为时延问题的时延参数,通过交叉验证的方法选定最优时延参数,并建立综合评价指标对模型进行评估。最后,利用试验样本对预测模型进行了验证,并以定相燃弧损耗样本为例通过接触器电寿命映射模型对剩余电寿命进行了计算。结果表明,所提出的方法能够成功地定量评价接触器在三相不均匀燃弧损耗情况下的剩余电寿命,且能够直观表现剩余寿命的变化过程,预测误差仅为0.9%~12.1%。

基于FSC和TCSC混合复用的交直流混联线路潜供电弧特性

为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(fixed series compensation,FSC)和可控串补(thyristor controlled series compensation,TCSC)混合复用抑制潜供电弧的方法。此外,为满足线路对高补偿度的需求,设计FSC和TCSC混合复用串补度最佳配置方案。结果表明,交直流混联线路采用串补度40%的双平台分散布置方式,潜供电流与恢复电压幅值达到最小,燃弧时间最短。高补偿度串补线路TCSC采用串补度10%、20%的配置方案更利于熄弧,提高重合闸成功率。

基于混合无功功率补偿的交直流混联线路潜供电弧抑制措施

随着电压等级提高、输送功率增大,系统无功功率变化更加频繁,不利于熄弧,输电线路安全稳定运行受到严重威胁。基于交直流混合无功补偿线路研究了混合无功补偿装置(hybrid reactive power compensation,HRPC)补偿度对潜供电流与恢复电压影响,分析分级可控高抗与小电抗联动控制的措施对潜供电弧抑制效果,提出一种改进型旁路断路器时序控制策略。结果表明,串补度20%、补偿度70%及小电抗700 mH时,潜供电流与恢复电压幅值最小,抑制效果最佳。此外,采用潜供电弧熄灭后旁路断路器断开的控制策略能够进一步加快熄弧速率,提高单相重合闸成功率。研究成果为HRPC在远距离大容量混联线路中应用提供理论依据和技术支撑。

交流及脉冲GTAW铝合金焊接电弧温度及其形态数值模拟研究

控制钨极氩弧焊接(GTAW)的焊接电弧温度、形态等特性是制定其焊接工艺、提高其焊接质量与效率的措施之一。采用数值模拟研究方法,研究了6061铝合金GTAW焊接过程钨极氩弧温度及其形态,对交流及脉冲钨极氩弧温度及其形态进行了比较与分析,阐述了随焊接电流变化钨极氩弧温度及其形态变化规律。研究结果表明,在交流钨极氩弧焊接电流方向变化时焊接电弧将熄弧,其温度下降;焊接电弧形态基本保持钟罩型,其高温区域发生变化;在交流钨极氩弧达到稳定状态时,正接焊接电弧温度较反接的高,焊接电弧高温区域距工件更近,焊接电弧径向尺寸较反接的大;脉冲电流钨极氩弧焊接过程不会熄弧;从峰值到基值焊接电流过渡过程中,焊接电弧沿径向收缩,相反,焊接电弧沿径向扩张,其形态似“腰鼓”状;脉冲基值电流焊接电弧温度较峰值电流的小。

基于电气特性-物理参数耦合的交流电弧炉模型

现有电弧炉模型主要关注电弧内部与外部特性的联系,割裂了电弧内部微观下电气与物理的耦合影响,难以体现电弧的电热物理本质,导致仿真精度有所欠缺。针对上述问题,该文提出一种改进的新型交流电弧炉模型。首先,在电子连续性方程的基础上,构建电弧的电气特性模型;其次,根据弧柱磁压缩力平衡方程和瞬时能量平衡方程分别构建电弧的压强、温度等物理参数模型,推导得到电弧内部的电气特性与物理参数之间的耦合机理,得到两者的耦合模型;然后,基于电弧炉变压器二次侧额定电流和最大电弧温度之间的关系,利用麻雀搜索算法对电弧温度曲线进行辨识,确定物理模型的各个参数;最后,依据50 t、55 t炼钢交流电弧炉的现场实测数据,在Matlab/Simulink平台上搭建模型并验证模型的正确性。仿真结果表明,所提模型更符合交流电弧炉实际运行过程中的物理本质,能更精确地反映其谐波、电压波动特性。

跷板开关交流电弧特性的实验研究

交流电弧特性曲线是评价开关分断能力的重要依据。通过测试跷板开关分断过程的触点电压和触点电流波形,分析了磁吹对交流电弧特性的影响,并确认了跷板开关存在机械开断和电流过零2种熄弧原理。所得结论对于提高跷板开关分断交流负载能力具有参考价值。