瓷柱真空灭弧室的绝缘性能

本文着重介绍了瓷柱的绝缘性能和用瓷柱支撑电弧屏蔽罩对真空灭弧室绝缘性能的影响。     

真空灭弧室的几种主屏蔽罩电场仿真分析

<正>介绍了在电力系统一个重要元件——真空灭弧室的主屏蔽罩结构设计。随着真空灭弧室产品向小型化和低成本发展,主屏蔽罩的结构也发生相应变化。真空灭弧室作为真空断路器的核心元件,其质量性能好坏直接决定了真空断路器的使用性能表现。市场上,真空灭弧室典型结构组成如图1所示。主屏蔽罩作为真空灭弧室的关键零件之一,主要作用是当触头之间产生电弧时有大量金属蒸气和液滴向真空灭弧室四周喷溅,这些电弧生成     

基于ANSYS的40.5kV真空灭弧室电场分析

建立了电压等级为40.5 k V真空灭弧室的二维模型,利用有限元软件ANSYS计算并分析了该40.5 k V真空灭弧室在不同主屏蔽罩半径下的电场和电位分布,对比了不同主屏蔽罩半径下触头沿面的电场强度分布以及波纹管屏蔽罩与主屏蔽罩弯角之间的电场分布。结果表明:1主屏蔽罩半径越大,其电场强度越小,当半径大到一定程度时,电场强度不再随主屏蔽罩半径的变化而变化;2当主屏蔽罩半径为57 mm时,该40.5 k V真空灭弧室内部场强分布最为均匀。     

72.5kV真空灭弧室电位和电场分布研究

为分析72.5 kV真空灭弧室的电位分布和电场分布及其影响因素,建立了其轴对称有限元分析模型,计算了其电位分布和电场分布,研究了真空击穿的面积效应,并分析了主屏蔽罩的结构尺寸及多个屏蔽罩对真空灭弧室内部电场分布的影响。结果表明:真空灭弧室动静触头之间、触头和屏蔽罩之间的电位变化比较显著,灭弧室内部电场分布不均匀;随着触头间隙距离、触头半径及倒角部分曲率半径的增大,触头表面有效面积将增大,而灭弧室内部最大场强将有所减小;增大主屏蔽罩的半径和长度,可以使屏蔽罩两端的场强有所减小,在真空灭弧室内安装多个屏蔽罩,可以改善内部电场分布。计算结果可为高电压等级真空灭弧室的优化设计提供参考。     

真空灭弧室中屏蔽罩电位动态测试及分析

本文通过测量真空灭弧室中屏蔽罩电位与电弧电压和恢复电压关系的动态变化波形，探讨真空灭弧室在短路电流分断过程中，真空电弧的燃弧规律和弧后介质强度恢复规律。在试验结果的基础上，对真空灭弧室屏蔽罩电位与触头间电压的动态关系进行了数学推导，从理论上分析了屏蔽罩电位的变化规律，证实这是一种研究真空灭弧室性能的可行方法。     

高压真空灭弧室内部电场分布的影响因素

为了解高电压真空灭弧室内部的电场分布情况,建立了真空灭弧室的电场数学模型。应用电场数值分析方法和有限元软件详细计算不同屏蔽罩与触头尺寸对真空灭弧室内部电场分布影响的结果表明,因高电压真空灭弧室开距较大,触头间隙不再是场强集中的区域,在高压真空灭弧室小型化设计过程中,除考虑电极间的绝缘外,更需考虑电极与屏蔽罩之间的绝缘。合理设计屏蔽罩的尺寸、位置和触头的形状可有效改善灭弧室内部的电场分布,提高真空灭弧室的耐压能力,从而为国内72.5kV以上电压等级真空灭弧室的研制提供了理论依据。     

ZW-12/630型10 kV断路器非全相分闸的原因分析及处理

1 现场情况 在一次设备例行试验中发现,某户外10 kV真空断路器分闸后A相仍处于合闸导通状态. 该断路器为ZW-12/630型,配CT23A-D型弹簧操动机构,2002年3月完成现场安装调试后于同年8月投入运行. 2原因分析 2.1 真空灭弧室的结构及开闭原理 真空灭弧室主要包括静触头、动触头、波纹管、主屏蔽罩、波纹管屏蔽罩、均压屏蔽罩、屏蔽罩法兰、绝缘外壳等部件.正常情况下,自由状态时的真空灭弧室动、静触头是自然闭合的导通状态,只有借助外力(来自操动机构的操作动力)的作用才能完成动、静触头的开断.     

瓷柱式真空灭弧室的电场分析

计算和分析了瓷柱式真空灭弧室的内部电场,同时经冲击耐压试验证明:瓷柱被金属蒸气污染是造成此种结构灭弧室容易发生内击穿的原因。     

真空断路器灭弧室漏气原因分析和消除方法

1故障经过 某供电公司在进行预防性试验时发现1台真空灭弧室被击穿。该灭弧室为玻壳真空灭弧室，经外观检查发现灭弧室内屏蔽罩由铜黄色变为红褐色，说明真空灭弧室内已有空气进入，所以屏蔽罩被氧化而变色。     

真空灭弧室设置不同屏蔽罩的均压作用

本文阐述了均压屏蔽罩在高电压真空灭弧室中的应用及其重要性,介绍了各种不同屏蔽罩在高电压真空灭弧室内所起的均压作用,触头开距与屏蔽罩之间的配合以及触头和屏蔽罩形状的分析。     

Effect of annealing and polishing on flashover characteristics ofceramic in vacuum

Experiments were carried out to study the effects of surface polishing and annealing of ceramic specimens on the dielectric breakdown characteristics of their surfaces. It was found that when the samples were annealed at 1000°C, allowing the residual stresses in their surfaces to decrease, the breakdown voltage rose, whereas with the polished samples, reductions of residual stresses resulted in a slight rise of the breakdown voltage. Prior to dielectric breakdown, a surface glow was observed, due to luminescence from electron bombardment and insulator surface defects. The starting voltage of luminescence rose when residual stresses were reduced. It is suggested that the mechanical strain due to surface defects contributes to dielectric breakdowns on ceramic surfaces     

高压断路器用的新型并联陶瓷电容器

本文介绍一种新研制成功的断路器用并联陶瓷电容器。该电容器采用经过改进的顺电体瓷料组成,具有无油、可靠性高和介损小等特点,适用于35kV真空断路器和SF_6高压断路器作并联电容器。     

Analysis and Performance of a Fixed Filter-Thyristor Controlled Reactor (FF-TCR) Compensator

A fixed Filter-Thyristor Controlled Reactor (FF-TCR) type of compensator is proposed to improve the power factor of a single phase thyristor-controlled inductive load and it is shown that this compensator gives better power factor improvement than the more generally used FC-TCR type of compensator. Analysis is carried out for the exact equivalent circuit of an FF-TCR compensator containing two filter branches tuned to the third and the fifth harmonics respectively. It is shown that with an FF-TCR compensator the power factor improvement is much better when the source impedance is large. However, even with a small source impedance, a reasonable improvement in power factor is realised. It is further shown that even when the source impedance is large the distortion in the terminal voltage waveform is kept within reasonable limits. The analytical results are verified experimentally.     

Effect of temperature on the partial discharge initiation voltageof capacitors

The paper describes a novel test arrangement to characterize the temperature dependence of partial discharge (PD) inception voltage in capacitors. The test arrangement consist of a temperature chamber, HV supply and PD detection circuit. The corona free operation voltage is 0 to 3.8 kV, temperature range is -50 to 200°C. Different type of capacitor PD inception voltage were measured at different temperatures. It was found that most commercial capacitor PD was lower than the rated voltage and increased with the temperature. In contrast, the higher quality chip type ceramic capacitor PD was above the rated voltage and decreased with the temperature. The paper concludes that the prediction of capacitor performance requires the measurement of PD at different temperatures     

SF6气体绝缘高压直流设备内部绝缘子用新型陶瓷材料特性探索

陶瓷材料具有高导热性、高机械强度,在SF6绝缘高压直流电气设备内具有一定应用潜力。该文探索了一种新型陶瓷材料的电导特性、表面电荷特性、机械特性及耐酸蚀性,并与工程用环氧树脂/Al2O3复合材料进行了对比,研究发现:室温、低场下陶瓷体积电阻率为4.5×1015W×m,且其温度依赖性较环氧复合材料低;正、负极性直流电压下,陶瓷表面均积聚正极性表面电荷,且最大电荷密度仅为0.21pC/mm2,较环氧复合材料低54%;此外,陶瓷材料表现出了较优的机械与耐酸蚀特性。基于材料物化结构的电导机理模型及温度梯度下支柱绝缘子的电场计算结果,进一步验证了陶瓷所具备的优异特性与巨大潜力。研究成果为提升SF6绝缘高压直流电气设备沿面绝缘性能提供了一种新的思路,为新型陶瓷材料的工程应用提供了理论基础。     

Effects of load modeling in security constrained OPF studies

Results of computational experiments carried out on an adaptation of the AEP/IEEE 30 bus test system are reported. Some selected buses were modeled using an exponential type of load model. Three cases are considered. In the first case it is assumed that the specified load at modeled buses is obtained with unity voltage. In the second case it is assumed that the transformer taps have been adjusted to give all industrial-type consumers one per unit at the low-voltage panel when the high-side voltage corresponds to the standard optimal power flow (OPF) solution. The third case differs from the second in that the specified power demand is assumed to take place when the high-side voltages correspond to the intact case of the standard security constrained OPF solution. It is concluded that a decrease in fuel cost can be obtained in some instances when load models are incorporated in security constrained OPF studies during contingencies only. In situations where a decrease in fuel cost is obtained in this manner, the magnitude of decrease depends on the total percentage of load fed by fixed tap transformers and the sensitivity of these loads to modeling     

新型可加工陶瓷真空中冲击闪络特性的研究

为了克服氧化铝陶瓷存在加工难度及脆性大等缺点,研制成功了一种新型低熔点可加工微晶玻璃陶瓷,它具有良好的力学、热学和可加工性能,但需进一步了解其电气性能。因此,测量了这种新型陶瓷的介电特性;考察了其在真空中脉冲电压下的沿面耐电特性;对比分析了氧化铝陶瓷和可加工陶瓷的表面耐电性能及不同添加剂成分与不同比例的添加剂对可加工陶瓷表面耐电性能的影响。结果发现,这种可加工陶瓷符合电工陶瓷的标准,其表面耐电性能优于氧化铝陶瓷,可替代现有的陶瓷材料,并获得了较好的配方设计。     

分体式智能塑壳式断路器在低压成套开关设备中的应用

介绍了分体式智能塑壳断路器在低压开关柜中的应用及前景,将其一拖一产品用于低压抽出式开关柜的抽屉单元中或将一拖多（最多一拖八）等群组控制产品用于低压固定式或抽出式开关柜。采用一拖多产品时,在有上下级关联的系统中可实现区域选择性联锁和负载监控功能,大大提高系统的可靠性。分体式智能塑壳断路器的智能控制器安装在各种低压成套开关设备和配电装置的板面上,不但可增加多种功能和可通信,还可提高整体低压成套开关设备产品的安装、调试和使用。     

Modeling power supplies of LED lamps

In the paper, the model of the power supply of the LED lamp in the form dedicated for SPICE is proposed. The form of the worked out by the authors' model is presented, and the results of experimental verification of this model for the LED lamp of the type CLA25 are shown. The presented model is elaborated only for the power supply of LED lamps, in which the constant output voltage is stabilized. This model has the form of a subcircuit for SPICE, and it describes the influence of load resistance, amplitude of the input voltage, and the ambient temperature on both the input current and the output voltage. It is confirmed that the worked out model describes correctly both the waveform of the current received from the electroenergy network and the influence of the load current, the ambient temperature, and the supply voltage on the output voltage.     

纳秒脉冲表面滑闪放电的电气和光学特性

为了研究纳秒脉冲表面滑闪放电特性,本文采用一种新型三电极结构的激励器,通过纳秒脉冲叠加负直流的混合激励模式产生表面滑闪放电。实验研究了电压脉冲分量、电压直流分量及两者的差值对纳秒脉冲表面滑闪放电特性的影响。实验结果表明,当脉冲电压幅值固定时,直流电压幅值的改变对脉冲侧电流的影响较小,但对直流源侧电流却影响显著,直流源侧电流随直流电压幅值的增加而增加,发生表面滑闪放电后峰值和速度均增加。直流电压幅值越大,直流源侧电流出现时刻越早。当直流电压幅值固定时,脉冲侧电流和直流源侧电流均随着脉冲电压幅值的增加而增加。实验中存在一个电压阈值(脉冲分量和直流分量电压差值)使纳秒脉冲表面滑闪放电发生,该阈值为22k V。此时发生表面滑闪放电,瞬时功率峰值、单脉冲能量峰值和稳态能量均迅速增加。脉冲直流电压差值相同时,脉冲分量主导脉冲侧电流的大小,直流分量主导直流源侧电流的大小,脉冲分量所占比例的大小对功率和能量损耗的影响较大。此外,利用数码相机拍摄放电图像研究了纳秒脉冲表面滑闪放电的光学特性,放电图像表明,在电极间施加合理的脉冲电压和负直流电压均可产生表面滑闪放电,实现等离子体的拉伸效果,在阻挡介质表面获得大面积的等离子体。