Research of Arc Chamber Optimization Techniques Based on Flow Field and Arc Joint Simulation

The preliminary design of an arc chamber in the 550 kV SF6 circuit breaker was proposed in accordance with the technicai requirements and design experience. The structural optimization was carried out according to the no-load flow field simulation results and verified by no-load pressure measurement. Based on load simulation results such as temperature field variation at the arc area and the tendency of post arc current under different recovery voltage, the second optimal design was completed and its correctness was certificated by a breaking test. Results demonstrate that the interrupting capacity of an arc chamber can be evaluated by the comparison of the gas medium recovery speed and post arc current growth rate.

Influence of the axial magnetic field on sheath development after current zero in a vacuum circuit breaker

After current zero,which is the moment when the vacuum circuit breaker interrupts a vacuum arc,sheath development is the first process in the dielectric recovery process.An axial magnetic field（AMF） is widely used in the vacuum circuit breaker when the high-current vacuum arc is interrupted.Therefore,it is very important to study the influence of different AMF amplitudes on the sheath development.The objective of this paper is to study the influence of different AMF amplitudes on the sheath development from a micro perspective.Thus,the particle in cell-Monte Carlo collisions（PIC-MCC） method was adopted to develop the sheath development model.We compared the simulation results with the experimental results and then validated the simulation.We also obtained the speed of the sheath development and the energy density of the ions under different AMF amplitudes.The results showed mat the larger the AMF amplitudes are,the faster the sheath develops and the lower the ion energy density is,meaning the breakdown is correspondingly more difficult.

Simulation of Arc Rotation and Its Effects on Pressure of Expansion Volume in an Auto-Expansion SF_6 Circuit Breaker

A 3D Magnetohydrodynamics （MHD） arc model in conjunction with an arc move- ment model is applied to simulate the arc rotation as well as to solve its effect on the pressure in an auto-expansion circuit breaker. The rotation of the arc driven by an external electromagnetic force is simulated in the case with 200 kA of the short circuit current and 16 ms of arc duration. The arc rotating process and the speed of arc rotation have been obtained in the simulation. A comparison of the pressure in the expansion volume with and without an external magnetic field has been carried out based on the calculation results of two cases. The results of the simulation reveal that the arc rotation, which causes more energy exchange between the arc and its sur- rounding gas, can evidently bring about the pressurization in the expansion volume, which would contribute to more effective arc quenching at current zero and further reducing operation power.

The Influence of Contact Space on Arc Commutation Process in Air Circuit Breaker

In this paper, a 3D magneto-hydrodynamic （MHD） arc simulation model is applied to analyze the arc motion during current interruption in a certain air circuit breaker （ACB）. The distributions of pressure, temperature, gas flow and current density of the arc plasma in the arc region are calculated, and the factors influencing the commutation process are analyzed according to the calculated results. Based on the airflow in the arc chamber, the causes of arc commutation asynchrony and the back commutation are investigated. It indicates that a reasonable contact space design is crucial to a successful arc commutation process. To verify the simulation results, the influence of contact space on arc voltage and arc commutation is tested. This research can provide methods and references to the optimization of ACB design.

550kV快速断路器液-机-气整机联合仿真

快速断路器可实现短路故障的快速切除,对保证电力系统安全稳定运行具有重要意义。针对一种快速响应、高速运动的新型液压操动机构,建立液压操动机构、传动系统和灭弧室之间的耦合关系,开展液-机-气联合仿真研究,分析不同操作功对动触头运动特性、液压缸缓冲特性和灭弧室反力特性的影响规律,在此基础上,对传动系统应力分布进行计算,对存在破坏风险的零部件提出改进策略,确定试验样机设计方案。研究结果表明:操作功对分闸速度影响明显,确定机构活塞杆侧作用面积为3160mm^(2),分闸速度提升至13.63m/s,触头机械分离时间缩短至4.45 ms,满足快速开断需求。随着机构操作功的提升,机构缓冲力峰值和灭弧室压气反力峰值提升明显,造成部分传动件应力值超标,通过优化液压操动机构缓冲性能以及传动件结构,设计出满足机械强度要求的传动系统。研究成果指导研发了操动机构试验样机,试验结果满足快速开断要求。

C_(4)F_(7)N/CO_(2)混合气体在高压断路器中熄弧特性分析

基于磁流体力学理论,对C_(4)F_(7)N/CO_(2)混合气体和SF_(6)气体的断路器在40 kA短路电流情况下的熄弧特性进行仿真计算,分析两种不同气体的温度特性、灭弧室气体压强。结果表明:相同气压下,9%C_(4)F_(7)N/91%CO_(2)混合气体在燃弧过程中产生的气体压强要比SF_(6)气体产生的压强小,混合气体断路器的燃弧过程中9%C_(4)F_(7)N/91%CO_(2)混合气体熄灭电弧能力相对于SF_(6)气体更弱些;对比电弧等离子体的径向温度,在SF_(6)气体的断路器中,其电弧等离子体的径向温度相较于9%C_(4)F_(7)N/91%CO_(2)混合气体的断路器更高。而在燃弧过程中,相较于SF_(6)气体下的电弧半径,混合气体下的电弧半径更大。当混合气体充气压强提升至0.8 MPa时,温度梯度得到提升,缩减了电弧半径,可有效地扩大径向冷却的作用,使电弧熄灭加速,断路器的熄弧性能能够进一步被提升。

Investigation of cathode spot characteristics in vacuum under transverse magnetic field (TMF) contacts

With the continuous improvement of current levels in power systems, the demands on the breaking capacity requirements of vacuum circuit breakers are getting higher and higher. The breaking capacity of vacuum breakers is determined by cathode spots, which provide electrons and metal vapor to maintain the arc. In this paper, experiments were carried out on two kinds of transverse magnetic field（TMF） contacts in a demountable vacuum chamber, the behavior of the cathode spots was recorded by a high-speed charge-coupled device（CCD） video camera, and the characteristics of the cathode spots were analyzed through the image processing method. The phenomenon of cathode spot groups and the star-shaped pattern of the spots were both discovered in the experiment. The experimental results show that with the condition of TMF contacts the initial expansion speed of cathode spots is influenced by some parameters, such as the tested current, contact gap, the structure of the contact, the contact diameter, the number of slots, etc. In addition, the influence of the magnetic field on the formation of the cathode spot groups, the distribution, and the dynamic characteristics of the cathode spots were analyzed. It is concluded that the characteristics of the cathode spots are due to the effect of the magnetic field on the near-cathode plasma. The study of the characteristics of cathode spots in this paper would be helpful in the exploration of the physical process of vacuum arcs, and would be of guiding significance in optimizing the design of vacuum circuit breakers.

550 kV快速断路器气流场仿真与开断性能

快速断路器能够显著缩短开断时间,提高系统暂态稳定性,保证电力系统的安全稳定运行。为此提出快速断路器灭弧室结构设计方案,建立磁流体动力学(magnetohydrodynamics,MHD)电弧数学模型,计算不同燃弧时间的快速断路器开断过程气室压强、喷口气流速度和电弧温度变化趋势,对比分析气压特性、电弧电导、弧后电流等关键开断参量,综合评估快速断路器开断性能,确定样机设计方案。研究结果表明:分闸速度11.7m/s、超程33 mm、充气压强0.65 MPa的灭弧室设计方案,具备7 ms短燃弧、11.5 ms中燃弧和16 ms长燃弧开断能力。样机顺利通过了T100(a)开断试验,短燃弧时间为7.4 ms、中燃弧时间为10.8 ms、长燃弧时间为16.1 ms,验证了仿真计算的有效性。该550 kV快速断路器成功将开断时间缩减至25 ms以内,对提高电网稳定性、可靠性具有重大意义。

高压断路器故障机理与操作机构故障诊断技术

该文主要探究高压断路器的故障机理以及操作机构故障的诊断方法。文章使用ANSYS软件创建高压断路器灭弧室的有限元仿真模型,通过施加载荷分析灭弧室结构对内部电场的影响。结果表明,屏蔽罩上电荷残余量与灭弧室内最大电场强度有直接关系,电荷残余量过大是导致高压断路器发生击穿故障的主要原因。随后提出一种基于CCA算法和SOM算法的故障诊断技术,并选取300组操作机构运行数据进行故障诊断,结果显示有2处故障。现场检修结果与诊断结果一致,说明CCA-SOM诊断技术正确。

SF_6断路器无载分闸灭弧室气流场控制的研究

对 SF6 断路器无载分闸过程中灭弧室电场和气流场进行了仿真计算。结果显示 ,断路器无载分闸速度以及灭弧室气流场分布影响冷态介质恢复特性。提出采用气流控制环来控制灭弧室气流场的观点 ,使断路器冷态介质恢复强度成为智能操作中的可控参数。

喷口结构对超高压SF_6断路器压力特性的影响

为有效控制喷口区域气流运动,提高高压开关开断能力,以550kV单断口超高压SF6断路器为研究对象,提出不同喷口气流管道流动结构,采用有限体积法对灭弧室内冷气流流动进行数值模拟。通过对比分析断口区域不同压力观测点的压力分布,得到喷口上下游压力差的定量描述,以反映开断过程中喷口气流的流动行为。仿真结果表明,喷口长度和型面结构参数是控制气流流动的主要因素。

基于真实气体模型的SF_6断路器中冷态气流场特性的仿真分析

准确地计算灭弧室内气流场特性对于SF6断路器优化设计有重要意义。基于真实气体模型(user-defined real gas model,UDRGM),运用线性插值与UDRGM相结合的方法来导入SF6的气体属性,并与流场控制方程组联合求解,研究了SF6断路器简化灭弧室冷态气流场的特性规律。通过分析监测点处的物理量发现,触头分开过程中,灭弧室内整体压力差不断增加,气体密度分布主要取决于气压的变化;在喷口区域,气压最大值出现在动触头端部中心位置,各监测点处的气压与马赫数受触头位置的影响较大,当触头运动到监测点时,马赫数与气压会发生跃变,而喷口内部两触头间的气压变化梯度却很小。结果表明,基于UDRGM建立的SF6断路器冷态气流场分析新方法可有效地提高计算精度,也为热态气流场的研究提供了基础。

高压SF_6断路器电弧动态模型研究

提出了在二维N-S方程和湍流模型求解基础上的喷口电弧等效电阻网格法,建立了新型电弧动态物理-数学模型,充分考虑了灭弧室内电弧温度、压力等物理因素的影响,气吹对电弧形态的影响以及电弧电流的自适应调整,以反映整个开断过程中电弧的动态变化。并在对高压SF6断路器气流场N-S方程和k-ε方程求解研究的基础上,对500kV单断口SF6断路器短路开断情况下,跨音速、可压缩、复杂流路、变边界条件的气流场进行求解,实现了电弧动态变化过程的气动模拟,为进一步研究电弧能量的利用及更有成效地进行高压断路器开断过程的仿真研究奠定基础。

高压SF_6断路器电弧与气流相互作用研究

以二维N-S方程和湍流模型为基础,在考虑了灭弧室内吹弧气流温度、压力等物理因素影响后,建立了高压SF6断路器电场/气流场数值求解模型,反映了气吹对电弧形态的影响及电弧电流的自适应调整。并以500kV单断口SF6断路器短路开断为例,进行了电场及跨音速、可压、复杂流路、变边界条件的气流场求解研究,并对燃弧区域电弧堵塞、动态电弧与吹弧气流的相互作用、气流压力、速度变化以及电弧堵塞前后喷口区域质量流与气流压力定量变化进行了数值仿真分析,为进一步定量研究电弧能量有效利用及更有成效进行高压断路器开断过程仿真研究奠定基础。

高压断路器运动特性仿真

根据高压断路器分闸运动原理,建立了高压断路器液压机构与压气室的联合运动方程。通过仿真,分析了运动方程中各种力参数对分闸运动特性的影响和操作功特性,并且从理论上提出了调节分闸运动特性的两种途径。

能量流电弧模型及SF_6断路器在短路开断下的应用研究

基于高压SF6断路器开断短路电流时电弧形态与特性是决定开断特性重要因素这一事实，提出并建立一种新型电弧模型——能量流电弧模型。建模中充分考虑在整个开断过程中电流的变化、气流参数的改变对电弧形态的影响及电弧导致高温气体对整个气流场的相互影响。将此模型与气流场求解的N-S方程组相耦合并进行求解，较好地反映了气流场与电弧间相互作用。计算结果证明，该模型可较好反映灭弧室内能量流动、变化及发展规律。

SF_6罐式高压断路器三维电场计算与分析

基于开发的三维有限元仿真软件计算了 SF6 罐式高压断路器灭弧室内的三维电场 ,得到灭弧室内的电场强度分布 ,发现喷口对灭弧室中电场分布的影响较大 ,它的存在使触头附近电场及其变化增大 。

电容器组投切用SF_6断路器介质恢复特性数值计算与试验研究

针对126 k V电容器组专用SF6断路器介质恢复特性进行数值计算与试验研究。对断路器灭弧室电场和气流场进行数值计算,依据流注理论,得到断路器触头间击穿电压曲线;搭建试验回路对断路器触头间隙动态击穿特性进行试验,测量断路器合闸和分闸过程中的击穿电压;结合数值计算与试验结果,分析不同压强对断路器合、分闸过程击穿电压的影响,给出高压SF6断路器介质恢复特性的变化规律。研究结果表明:对于同样的触头间隙,合闸过程(平均速度4.7 m/s)击穿电压大于分闸过程(平均速度9.6 m/s)。

利用电弧动态数学模型的低压断路器开断过程仿真分析

低压断路器开断过程仿真的关键内容是如何建立开断过程的电弧数学模型,并将其与其它开断过程的物理现象相耦合。通过对虚拟样机软件ADAMS进行二次开发,将电弧动态数学模型应用到低压断路器的开断过程仿真,并结合有限元软件ANSYS,建立了耦合复杂机械运动﹑电路﹑磁场和电弧数学模型的低压断路器开断过程仿真模型。通过将建立的仿真模型应用到一带双向斥开触头系统的塑壳断路器,研究了静触头压力大小对该塑壳断路器开断性能的影响。实验结果表明,利用所提出的仿真模型研究低压断路器的开断过程是可行的。

不同旋气槽数对SF_6断路器三维气流场影响

针对SF6断路器提出了在气体通道的喷口上游增加旋气槽,实现将传统的轴向吹弧改为旋转吹弧的新型喷口结构。以110kVSF6断路器为研究对象,采用有限体积法对有槽和无槽结构的SF6断路器进行数值模拟并研究了旋气结构对气流场参数的影响。在理论研究表明带有旋气槽结构的断路器具有很强的吹弧能力的基础上,进一步在保证灭弧室内气体流量不变条件下,进行了改变旋气槽槽数对吹弧能力影响的深入研究,得到不同旋气槽数对气流速度分布的影响规律,为进一步定量研究新型旋气式SF6断路器奠定基础。