共查询到19条相似文献,搜索用时 140 毫秒
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500kV断路器并联电容外绝缘击穿几率的分析 总被引:1,自引:0,他引:1
为正确估计较高幅值操作过电压在实际系统运行中发生的概率和可能的危害,更合理地配置设备绝缘水平和限制保护措施,针对某500kV线路在解环操作过程中发生的三相断路器并联电容外绝缘击穿的事故现象,等值模拟了该系统的运行方式,建立了输电线路bergeron分布参数数学模型,对事件发生的全过程进行了计算和统计分析,从而得出在被操作线路末端出现一相断口击穿的概率较低,但一旦发生单相断口击穿,就极易在其它两相上形成较高幅值的过电压,导致三相断口同时击穿的结论。并针对该现象提出严格断路器断口耐压水平控制和加装断路器断口击穿继电保护功能等防范措施。 相似文献
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电容器组投切断路器触头烧蚀劣化后会改变合闸预击穿时间,这不仅会影响选相合闸效果,同时也说明预击穿电弧持续时间可作为衡量触头烧蚀状态的指标之一。建立了126 kV SF6断路器灭弧室内合闸预击穿过程电—流体耦合仿真模型,研究了触头劣化过程中合闸预击穿特性,并提出了预击穿时间带电检测方法。结果表明:合闸过程中场强最大点总是出现在静弧触头表面;灭弧室内SF6气体密度几乎保持不变;110 kV电压等级相电压下,触头预击穿电弧持续时间随烧蚀程度变化的试验值与仿真值吻合良好。从电场畸变角度解释了随着触头的表面烧蚀劣化程度增大对应预击穿时间的变化规律,结果可为断路器选相合闸策略和触头状态评估提供理论指导。 相似文献
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苑舜 《辽宁电机工程学报》1996,(2):34-38
在FA4-550型SF6断路器切合58km空载线路试验中发生多次预击穿(也称预击穿自熄弧现象)。这一现象在以和主切合空载长线(175km,301km)试验中均未发生过,本文从SF6击穿机理、SF6断路器的动作特性及波的传播过程计算对其进行分析和研究。 相似文献
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《高压电器》2013,(10):88-93
笔者旨在通过试验研究126 kV单断口真空断路器在全电压关合过程中出现的一种新现象,即关合过程中自电压跌落至大电流引入期间,出现预击穿电弧自熄灭、触头间隙多次击穿且电流引入时间呈波动性大现象。采用合成试验方法与直接试验方法分别对126 kV真空断路器进行全电压关合试验,OP2(a)和T100(a)。采用合成回路试验方法进行试验时,采用了两种关合装置。试验结果表明:采用合成试验回路进行全电压关合试验时,关合装置的时延远远大于300μs,不能满足IEC 62271-100—2008标准对高压合成关合试验的要求,且关合过程中触头间隙发生多次预击穿现象;采用直接试验回路进行全电压关合试验时,触头间隙同样会发生多次预击穿现象,且电流引入时间具有不稳定性(200800μs),这是高压真空断路器本身特性决定的。 相似文献
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《高压电器》2016,(3):1-6
12 kV真空断路器投切并联电抗器时可能会产生合闸预击穿现象,形成危险的过电压。为探明合闸预击穿产生过电压的情况和改进现有合闸仿真模型。笔者在运行电网上对一种型号的12 kV真空断路器合闸并联电抗器进行了一系列的现场试验研究,并对合闸预击穿暂态过程和现象进行了分析。结果显示:该型号真空断路器的合闸预击穿率高达50%,且合闸预击穿相对地过电压均可超过4.0 p.u.。统计得到其合闸操作不同期特性、预击穿暂态过程中断口间介质动态绝缘强度恢复曲线和高频电流熄弧特性,并在ATP-EMTP中搭建真空断路器合闸预击穿MODEL控制模型。考虑电缆三相间的寄生参数,对该型号真空断路器合闸并联电抗器进行三相仿真计算,与试验结果对比分析显示,仿真结果与试验结果基本一致。 相似文献
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从微观的角度分析外施横向磁场下直流真空断路器弧后金属蒸汽击穿过程。首先,建立了可以描述直流真空断路器弧后金属蒸汽击穿过程的粒子模拟-蒙特卡洛碰撞仿真模型,确定了弧后金属蒸汽击穿判据;其次对比了不同横向磁场强度下弧后金属蒸汽击穿的发展过程,分析外施横磁强度对弧后金属蒸汽击穿的作用;最后,分析了外施横向磁场强度对弧后金属蒸汽击穿时刻的影响。研究结果表明:场致发射提供了金属蒸汽击穿的初始电子,是诱发金属蒸汽击穿的“种子”,电子崩的出现意味着金属蒸汽击穿的发生;横向磁场会降低真空间隙内的电子数和铜离子数,这是因为间隙内的电子和铜离子会在横磁的作用下横向扩散;横向磁场越大,金属蒸汽击穿速度越慢,当外施磁场由0 mT增加至2 000 mT时,击穿时刻由1.913×10-7 s增加至2.72×10-7 s。本文的研究结果有助于理解外施横磁下直流真空开断的弧后金属蒸汽击穿过程,可为低压直流真空断路器的开发提供理论依据。 相似文献
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提高断路器限流特性的研究 总被引:1,自引:1,他引:0
背后击穿现象降低了断路器限流特性,采用改善气流流动通道的方法是减少背后击穿现象的有效途径.本文介绍了对灭弧栅进行改进以改善气流流动通道,减少背后击穿现象的过程,以及改进后断路器的试验效果. 相似文献
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低压断路器用于接通和分断电路中的电流。当故障电流产生时,动触头和静触头打开,在触头间产生电弧,随后在电磁场和气流场的作用下向灭弧栅片运动。在运动过程中会出现电弧的停滞和后退的重击穿现象,严重降低了断路器的开断性能。该文以磁流体动力学(MHD)为基础建立了三维空气电弧等离子体在外部磁场作用下运动的数学模型,此模型可以预测电弧的重击穿现象,并发现当灭弧室的出口面积为60%时,电弧在3mT磁场的作用下运动时出现了重击穿现象,而当磁场增大到5mT时重击穿现象消失。此外,还发现当磁场为10mT时,在出口面积分别为20%、60%和100% 3种情况下电弧均可以顺利到达栅片,在运动的过程中没有电弧重击穿现象的发生。 相似文献
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Kamikawaji T. Shiori T. Funahashi T. Satoh Y. Kaneko E. Ohshima I. 《Power Delivery, IEEE Transactions on》1993,8(4):1789-1795
The performance of vacuum circuit breakers in switching shunt capacitors depends much more on in-rush current than on interrupting current. This is because when contacts that were fused together by pre-arcs during contact closing are forcibly separated, large protrusions are formed on the contact surface, making it easier for microparticles to be detached from the protrusions. Microparticles are also produced on the entire surface of contacts by mechanical impact or cold weld. Current interruption of a certain magnitude, however, has a conditioning effect because moderate arcs can eliminate such microparticles and lower the protrusions. To clarify the relationship between the behavior of microparticles and the dielectric breakdown, a laser scattering technique was employed. The authors found a microparticle-induced breakdown phenomena that could explain the mechanism of long delayed restrikes that is occasionally observed in vacuum circuit breakers 相似文献
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喷口型面及尺寸对SF6高压断路器介质强度恢复特性的影响 总被引:2,自引:0,他引:2
SF6高压断路器的喷口对断路器开断过程中吹弧气体的流动特性起着控制作用,从而成为灭弧室的心脏。该文以252 kV SF6断路器为研究对象,研究了改变喷口喉部下游仰角、长度对灭弧室吹弧气体流动特性、介质强度恢复特性的影响;应用激波理论和拉伐尔喷口中流速与截面比的关系,研究了局部"放-收"型面及2段型面对吹弧气体的控制作用及对介质强度恢复速度的影响;比较了在不同的喷口尺寸及型面下介质强度的恢复速度,得出喷口下游的型面对开断过程中介质强度恢复速度影响显著的结论。这对SF6高压断路器喷口的优化设计及灭弧室小型化设计具有重要的实际意义。 相似文献
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M. I. Baranov 《Russian Electrical Engineering》2017,88(1):19-22
A resistive protection circuit of high-voltage pulse capacitors with powerful capacitive energy storage (CES) in multimodule implementation from the emergency overcurrents arising in the individual modules of CES when internal or external electric breakdown of isolation of capacitors was proposed. The main distinctive feature of this circuit is separate operation of CES modules at the stage of charging of parallel-connected capacitors and their operation together at the stage of discharge of the capacitor of modules at the total electrical load. This mode prevents the explosion-like destruction of their protective graphite–ceramic fixed resistors of TVO-60 type in an emergency arising upon breakdown of a CES capacitor at the charge stage. The calculation results of the main electrotechnical parameters of the proposed resistive protection circuit are presented. The quantitative determination of such parameters of the protective circuit of CES indicates its practical feasibility in the area of high-voltage pulse technology. 相似文献
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Schellekens H. Gaudart G. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(3):613-619
This study focuses on a compact vacuum circuit breaker (CB) for nominal voltage of 72.5 kV, nominal current of 2000 A and short circuit current of 31.5 kA. The dielectric conception of the vacuum interrupter (VI) is based on a multiple floating shield configuration which reduces the risk of total breakdown due to partial breakdown between the contacts and shield. An optimised electrical field distribution on the contact surface with the maximum field pointing towards the floating shield is arranged and hence reducing the breakdown effective area of the contacts facing each. All tests have been performed on a specially designed single-phase circuit breaker pole-unit equipped with a low energy spring type mechanism. Interruption performance was confirmed in direct tests. The circuit-breaker pole was proved to be restrike-free with respect to cable charging class C2. Dielectric tests in new condition and after interruption tests confirmed the announced ratings. These tests confirm the feasibility of this HV-CB with 25% more compact VTs based on the outlined dielectric conception. 相似文献
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For metalized polymer film capacitors, the dynamics of electric field on the electrode surface and its resulting energy dissipation influence the onset and scale of breakdown discharges within the capacitor unit, which in turn is indicative of the reliability and lifetime. To gain an understanding of the dependence of surface electric field on key system parameters, an equivalent circuit model is developed to simulate the temporal evolution of the, electric field distribution within a dc film capacitor subjected to an external impulse electric stress. A mosaic pattern of electrode segmentation is taken into account by means of an effective surface resistance and its effects on surface electric field and energy dissipation are computed numerically. Also considered are the effects of the number of electrode segments across a given length. In addition, electric energy dissipation is calculated to assess the level of possible temperature rise within the capacitor. By addressing these two issues, it is shown that the numerical code developed and its underlying methodology can serve as a complimentary tool to the present practice of capacitor designs and performance assessment 相似文献