SF6/N2混合气体绝缘特性实验研究

通过安托万方程和拉乌尔定律,研究了不同混合方案下SF6/N2混合气体的液化温度,结合混合气体全球变暖潜能值(GWP)研究结果,分析混合气体的理化特性.文中搭建混合气体绝缘特性试验平台,测试不同混合方案下SF6/N2混合气体的工频击穿电压和直流击穿电压,分析了混合气体中SF6含量对混合气体绝缘性能和理化性能的影响规律.研...     

SF6/N2混合气体的工频击穿特性研究

通过理论分析对SF_6/N_2混合气体的工频击穿特性进行了研究,得出SF_6/N_2混合气体中SF_6气体的最优比例是20%～30%,同时在其他条件不变的情况下将混合气体压力提高至1.4倍即可具备与纯SF_6气体相同的工频击穿电压。试验结果也验证了分析结论的正确性,表明SF_6/N_2混合气体代替纯SF_6气体作为绝缘介质是完全可行的。     

N2/SF6混合气体在气体绝缘管道电缆中的应用

本文论述了N2/SF6混合气体的优点及其应用于气体绝缘管道电缆(GIC)的可能性,认为N2/SF6的混合气体应用于GIC具有重要的社会和经济意义。     

基于SF6混合气体绝缘性能的设备补气策略研究

随着电力需求的增长和环境保护要求的提高,SF6气体的使用逐渐受到限制.SF6混合气体在一定程度上减少了SF6气体用量,目前已经在电气设备中应用.文中针对SF6混合气体在220 kV气体绝缘组合电器(GIS)中发生泄漏引起的绝缘变化展开研究,通过改变微量的气压值和混合比,探究混合气体的绝缘性能变化,分析气压、混合比因素对工频击穿电压的影响规律,获取各气压下各比例混合气体的绝缘强度曲线图,从而得到保证设备安全稳定运行的补气策略.研究发现,混合气体击穿电压的变化规律呈现出随着压强和混合比的提高,非线性程度增大的特点,并且得到了设备安全运行的混合比和气压的边界值.文中的研究可以为SF6/N2混合气体绝缘设备提供运维规程和技术标准,同时为制定混合气体的检测技术标准奠定基础.     

SF6/N2混合气体综合检测技术研究

为应对全球温室效应,减少电力设备中温室气体SF6的使用量,提出了SF6混合气体的研究方案。目前SF6混合气体是短期内有效减少SF6气体在电力设备中使用量的方法之一。初步研究表明,SF6/N2混合气体具有较强的电气绝缘性能,使得SF6/N2混合气体具有极好的应用前景,因此做好对SF6/N2混合气体的电气设备,特别是GIS的监督和管理变得非常重要。基于此,研发了一款集SF6/N2混合气体混气比、湿度及分解产物检测为一体的检测仪器,并介绍了SF6/N2混合气体检测技术的原理及试验情况。     

550kV SF_6/N_2充气母线绝缘性能研究

由于SF6气体的温室效应,减少SF6气体的使用具有深远的社会意义,用SF6/N2混合气体取代纯SF6气体作为高压电器设备的绝缘介质是减少使用SF6气体的有效措施。介绍了SF6/N2混合气体的优点。从气体放电理论出发,对不同比例SF6/N2混合气体的绝缘性能进行了分析,结果表明:SF6体积分数仅为20%的SF6/N2混合气体击穿强度为相同气体压力纯SF6的70%左右;若SF6体积分数为20%的SF6/N2混合气体的击穿强度要达到纯SF6气体的击穿强度,其总压力应为纯SF6气体的1.4倍。新东北电气集团高压开关有限公司研制的采用20%SF6和80%N2混合气体绝缘,总压为0.6 MPa的550 kV SF6/N2混合气体母线在机械工业高压电器产品质量检测中心(沈阳)顺利通过了绝缘型式试验,且其雷电冲击耐受水平高达1 842.5 kV。因此,用SF6/N2混合气体作为550 kV母线的绝缘介质是切实可行的。     

SF6／N2和SF6／CO2的绝缘特性及其比较

介绍在Ｅ／Ｐ值为２６．３～９４．０ＫＶ／ｍｍＭＰａ的范围内采用稳态汤逊法（ＳＳＴ）测量ＳＦ６／Ｎ２和ＳＦ６／ＣＯ２的电离系数α和吸附参数η，求出了各混合比下的ＳＦ６／Ｎ２，ＳＦ６／ＣＯ２的临界耐电强度值（Ｅ／Ｐ）ｌｉｍ，并分析了两种混合气体的绝缘特性。     

N_2/SF_6混合气体的绝缘特性

为了探讨 N_2/SF_6混合气体代替纯SF_6气体作为气体绝缘输电管道绝缘介质的可行性,通过对低含量SF_6混合气体在不同混合比和压力下的工频及操作冲击耐电强度试验,分析了混合气体的绝缘特性。研究结果表明:在不改变现有输电管道结构和尺寸的情况下,可适当增加低含量SF_6混合气体的压强来保证输电管道的绝缘强度。     

550kV SF_6/N_2充气母线绝缘性能研究

由于SF6气体的温室效应,减少SF6气体的使用具有深远的社会意义,用SF6/N2混合气体取代纯SF6气体作为高压电器设备的绝缘介质是减少使用SF6气体的有效措施。介绍了SF6/N2混合气体的优点。从气体放电理论出发,对不同比例SF6/N2混合气体的绝缘性能进行了分析,结果表明:SF6体积分数仅为20%的SF6/N2混合气体击穿强度为相同气体压力纯SF6的70%左右;若SF6体积分数为20%的SF6/N2混合气体的击穿强度要达到纯SF6气体的击穿强度,其总压力应为纯SF6气体的1.4倍。新东北电气集团高压开关有限公司研制的采用20%SF6和80%N2混合气体绝缘,总压为0.6 MPa的550 kV SF6/N2混合气体母线在机械工业高压电器产品质量检测中心(沈阳)顺利通过了绝缘型式试验,且其雷电冲击耐受水平高达1 842.5 kV。因此,用SF6/N2混合气体作为550 kV母线的绝缘介质是切实可行的。     

SF_6—CO_2混合气体的绝缘强度

研究表明,虽然SF_6—CO_2混合气体在均匀电场中的击穿强度稍逊于同样混合比的SF_6—N_2混合气体,但在不均匀电场中的击穿强度、特别是在雷电冲击电压下的击穿强度,却优于SF_6—N_2.此外,SF_6—CO_2在气膜复合绝缘中的局部放电特性也优于SF_6—N_2混合气体.     

V-t characteristics of SF6 gas during lightning surges

The waveform of a standard lightning impulse differs greatly from those of actual lightning surges acting on GIS. This raises the problem of the equivalence of the standard lightning impulse. This report describes the effect of voltage waveforms on insulating performance in an SF₆ gas gap subjected to fast oscillating impulse voltages simulating actual lightning surges, and the evaluation of V-t characteristics by applying the equal area criterion. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(4): 1–11, 1997     

Insulation characteristics of SF6 gas for nonstandard impulse voltage polarity reversal pulse waveforms

Evaluation of insulation strength for lightning surge that actually enters into substations is important in estimating insulation reliability of gas‐insulated equipment. The standard lightning impulse voltage (1.2/50 µs) is used for factory tests. However, the actual lightning surge waveforms in substations are complex and are usually superimposed with various oscillations. Insulation characteristics of SF₆ gas as a function of such complex voltages have not been sufficiently clarified. This paper deals with gap breakdown characteristics in SF₆ gas under submicrosecond pulses. Breakdown voltages are lower under a polarity reversal condition than under a monopolarity condition. The cause of this difference is discussed while observing discharge propagation using an image converter camera. The electrode size effect is also discussed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 18–25, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10246     

SF_6/N_2混合气体电击穿特性仿真及实验

通过求解两项近似Boltzmann方程,得到SF_6/N_2的放电参数,并将该参数引入流体模型。结合有限元法和通量校正传输法对SF_6/N_2的流注放电过程进行循环迭代求解,计算其击穿电压。以均匀电场中压强0.1~0.6MPa、间隙5mm为例进行数值模拟,通过气体放电实验对计算结果进行验证。根据计算及实验结果得到不同混合比、压强下SF_6/N_2的协同效应系数,分析采用上述计算方法研究混合气体协同效应的准确性。为更全面地反映混合气体应用条件,进一步开展压强低于0.1MPa的SF_6/N_2击穿特性实验研究。研究表明:随着电子崩不断向前发展,放电间隙的空间电子数密度快速增长,SF_6放电过程中的空间电子数密度增长速度低于SF_6/N_2。0.1MPa下20%SF_6/80%N_2放电5ns时的电子数密度峰值达到4.6×1014m~(-3),而SF_6中该值仅为3.7×1012m~(-3)。当气压为0.1~0.6MPa时,SF_6/N_2击穿电压计算值与实测值的最大误差为9.23%,协同效应系数计算值随压强、混合比的变化趋势与实验结果相符,误差均值为5%。0.02~0.08MPa下SF_6/N2击穿电压、协同效应系数随压强、混合比的变化趋势与0.1~0.6MPa下的基本相同。     

Problems of the application of N2/SF6 mixtures to gas‐insulated bus

In designing a gas‐insulated bus (GIB) using N₂/SF₆ mixtures, there are many application problems, such as the mixture pressure needed in order to maintain the required dielectric and heat transfer performance. Problems of recycling SF₆ are also essential in applying N₂/SF₆ mixtures. This paper presents the minimum breakdown field strength at lightning impulse and the temperature rise of the conductor and enclosure as measured for N₂/SF₆ mixtures. Considering the dielectric and heat transfer properties, we clarify the problems of application of mixtures to a GIB and discuss the appropriate mixture ratio of SF₆ in designing a GIB comparable to the present dimensions. In addition, the lowest limit of SF₆ content in a liquefied recovering method is theoretically estimated for reference in practical SF₆ recovery from mixtures. It is important for design to consider both breakdown phenomena, including the area effect of electrode, and the heat transfer properties of mixtures. © 2001 Scripta Technica, Electr Eng Jpn, 137(4): 25–31, 2001     

Insulation properties of a CO2/N2 50% SF6 gas mixture in a nonuniform field

This paper describes partial discharge (PD) inception and breakdown voltage characteristics of a CO₂/N₂/SF₆ gas mixture in a nonuniform field. These voltage characteristics were investigated with ac high voltage by changing the mixture rate of each gas of CO₂, N₂, and SF₆ gas and the gas pressure from 0.1 MPa to 0.6 MPa. It was found that adding a small amount of CO₂ gas into a N₂/SF₆ mixture causes a drastic increase in the breakdown voltage. For instance, when the mixture rate of SF₆ in N₂/SF₆ gas mixture is 50%, with the addition of 1% CO₂ the maximum breakdown voltage becomes 1.31 and 1.15 times higher than that of a 50% N₂/50% SF₆ gas mixture and pure SF₆ gas, respectively. Moreover, those voltage characteristics of a CO₂/N₂/SF₆ gas mixture were also investigated by changing the electric field utilization factor as well as by applying positive and negative standard lightning impulse voltages in order to discuss the corona stabilization effect, which seems to be one reason for the drastic increase in the breakdown voltage. These results and breakdown mechanism of the CO₂/N₂/SF₆ gas mixture are discussed on the basis of the corona stabilization effect and the dissociation energies of the component gases by observing PD light images, PD light intensities through a blue and red filter, and PD current waveforms. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(3): 34–43, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10019     

基于分形理论的SF_6/N_2混合气体放电仿真

为了研究SF_6/N_2混合气体电介质击穿现象,利用编写的Matlab程序对放电通道发展过程进行数值模拟,并结合分形几何原理计算放电树枝的分形维数。基于分形理论,建立了考虑空间电荷分布和引入物理时间的棒-板分形放电仿真模型,通过有限元方法(FEM)计算空间电场,并首次结合通量校正传输(FCT)法求解带电粒子连续性方程,研究了不同发展概率指数、不同放电阈值和SF_6含量变化下分形放电特性。结果表明:概率指数越大,SF_6含量越高,则分形维数越小,放电树枝分叉也越少;体积含量50%/50%的SF_6/N_2混合气体放电分形维数D=1.219 2,整个放电过程流注发展平均速度为1.15Mm/s,并得到了不同时刻空间电荷及轴向电场与电子浓度的分布。     

SF6组合电器运行中水分超标原因分析

在SF6组合电器（GIS）的运行过程中,SF6气体中的微量水分含量的多少直接影响到GIS设备的安全可靠运行。通过对现场运行过程的分析,找出GIS组合电器气室中SF6微量水分超标的原因,提出了处理方法和预防措施。分析表明,通过早期检测,采取预防措施,可最大限度控制GIS设备内部SF6气体中的水分,降低设备损伤速度。     

Creeping flashover characteristics in (N2/SF6) gas mixture under pulse voltage

The effect of a barrier between a needle electrode and a plane one in an (N₂/SF₆) gas mixture on creeping flashover was investigated using a microsecond pulse voltage. The SF₆ gas content was varied from 0% to 100%, and the gas pressure from 0.1 MPa to 0.3 MPa. The flashover voltage increased with increasing SF₆ gas content for a positive needle electrode. For a negative needle electrode, excepting the total pressure of 0.1 MPa, at which similar flashover characteristics were obtained to the positive case, a considerable decrease in flashover voltage was found in the case of a mixture of a few percent SF₆ in (N₂/SF₆) gas mixture at elevated total pressures. The corona behavior on the barrier in (N₂/SF₆) gas mixture was investigated by means of a high‐speed digital framing camera. © 2000 Scripta Technica, Electr Eng Jpn, 131(1): 1–9, 2000