Integrated Experimental and Simulation Investigation of Breakdown Voltage Characteristics Across Electrode Configurations in SF_(6) Circuit Breakers

This study investigates the breakdown voltage characteristics in sulfur hexafluoride(SF6)circuit breakers,employing a novel approach that integrates both experimental investigations and finite element simulations.Utilizing a sphere-sphere electrode configuration,we meticulously measured the relationship between breakdown voltage and electrode gap distances ranging from 1 cm to 4.5 cm.Subsequent simulations,conducted using COMSOL Multiphysics,mirrored the experimental setup to validate the model’s accuracy through a comparison of the breakdown voltage-electrode gap distance curves.The simulation results not only aligned closely with the experimental data but also allowed the extraction of detailed electric field strength,electric potential contours,and electric current flow curves at the breakdown voltage for gap distances extending from 1 to 4.5 cm.Extending the analysis,the study explored the electric field and potential distribution at a constant voltage of 72.5 kV for gap distances between 1 to 10 cm,identifying the maximum electric field strength.A comprehensive comparison of five different electrode configurations(sphere-sphere,sphere-rod,sphere-plane,rod-plane,rod-rod)at 72.5 kV and a gap distance of 1.84 cm underscored the significant influence of electrode geometry on the breakdown process.Moreover,the research contrasts the breakdown voltage in SF6 with that in air,emphasizing SF6’s superior insulating properties.This investigation not only elucidates the intricate dynamics of electrical breakdown in SF6 circuit breakers but also contributes valuable insights into the optimal electrode configurations and the potential for alternative insulating gases,steering future advancements in high-voltage circuit breaker technology.

Study on the Mathematical Model of Dielectric Recovery Characteristics in High Voltage SF6 Circuit Breaker

According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle＇s ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker＇s interruption characteristic.

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.

The Voltage Distribution Characteristics of a Hybrid Circuit Breaker During High Current Interruption

Hybrid circuit breaker （HCB） technology based on a vacuum interrupter and a SF6 interrupter in series has become a new research direction because of the low-carbon requirements for high voltage switches. The vacuum interrupter has an excellent ability to deal with the steep rising part of the transient recovery voltage （TRV）, while the SF6 interrupter can withstand the peak part of the voltage easily. An HCB can take advantage of the interrupters in the current interruption process. In this study, an HCB model based on the vacuum ion diffusion equations, ion density equation, and modified Cassie-Mayr arc equation is explored. A simulation platform is constructed by using a set of software called the alternative transient program （ATP）. An HCB prototype is also designed, and the short circuit current is interrupted by the HCB under different action sequences of contacts. The voltage distribution of the HCB is analyzed through simulations and tests. The results demonstrate that if the vacuum interrupter withstands the initial TRV and interrupts the post-arc current first, then the recovery speed of the dielectric strength of the SF6 interrupter will be fast. The voltage distribution between two interrupters is determined by their post-arc resistance, which happens after current-zero, and subsequently, it is determined by the capacitive impedance after the post-arc current decays to zero.

Analysis of Arc Characteristics and Flow Field in Arc Chamber of High-Voltage SF_6 Auto-Expansion Circuit Breaker

A new magnetic hydro-dynamics model for nozzle arc emphasizing the interaction of arc with PTFE （polytetrafluorethylene） vapour is established based on the conservation equations. The interruption of auto-expansion circuit breaker is simulated numerically by finite element method and the influence of PTFE vapour on the arc is analysed with this model. The results reveal that the flow field inside the arc chamber is determined by the arc current, the arcing time, the nozzle arc and the clogging of its thermal boundary. The establishment of quenching pressure relies on both SF6 gas and PTFE vapour that absorbed arc energy in the nozzle. The PTFE vapour leads to an increase in the pressure of nozzle arc obviously, and a decrease in the temperature of arc. But it enhances the temperature of arc at zero current and slows down the decreasing rate of arc temperature as the current decreases.

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.

Simulation of the Process of Arc Energy-Effect in High Voltage Auto-Expansion SF_6 Circuit Breaker

A new magnetic hydro-dynamics （MHD） model of arc in H.V. auto-expansion SF6 circuit breaker that takes into consideration nozzle ablation due to both radiation and thermal conduction is presented in this paper. The effect of PTFE （polytetrafluorethylene） vapor is considered in the mass, momentum and energy conservation equations of the constructed model. Then, the gas flow fields with and without conduction considered are simulated. By comparing the aforementioned two results, it is indicated that the arc＇s maximal temperature with conduction considered is 90 percent of that without considering conduction.

塑壳断路器短路分断能力提升方法研究

短路分断是断路器的核心功能,提高断路器的短路分断能力是市场的持续需求。针对有效提升塑壳断路器(Moulded Case Circuit Breaker,MCCB)短路分断能力的方法开展了研究。利用栅片电压测量分析法可以检测灭弧栅片在短路分断时切割电弧的情况,评估各灭弧栅片切割电弧的性能以及电弧在灭弧室内的动态特性,为电弧优化提供参考数据。利用有限元仿真的方法进行电磁力计算,有利于快速验证优化设计方案而免去实际的试验验证,节约产品的研发成本,缩短产品的研发周期。蒸汽喷射控制(Vapour Jet Control,VJC)产气材料的运用也能够进一步提高产品的短路分断能力。综合运用以上设计方法,能够在不会大幅增加研发成本的基础上,快速提升MCCB的短路分断能力,工程应用价值较好。

弧触头烧蚀程度对灭弧室内短路开断过程多物理场的影响

为研究SF 6断路器开断过程中弧触头烧蚀程度对灭弧室内多物理场变化的影响,建立了弧触头接触行程分别减小0、5 mm、10 mm和15 mm下灭弧室内开断过程的多物理场耦合仿真模型,获得了短路电流开断过程中灭弧室内温度、气流和电场分布特性。计算结果表明:开断过程中,弧道最高温度出现在弧根处,其值随弧触头烧蚀程度变化不大;随着弧触头烧蚀程度的加剧,SF 6气体最高速度不断减小,吹弧效果减弱;最大场强集中在静弧触头端部或动弧触头弧角处,且随弧触头烧蚀程度加剧而畸变更严重。基于此,根据流注理论的气体击穿判据计算了不同弧触头烧蚀程度下SF 6介质恢复特性,发现当弧触头接触行程减小15 mm时,临界击穿电压低于瞬态恢复电压,触头间隙可能再次击穿造成电弧重燃。研究结果可为SF 6断路器电寿命退化机理提供理论支撑。

断路器分合闸线圈烧毁的原因分析及改进方法研究

针对断路器分合闸操作过程中线圈烧毁现象,从断路器操作机构以及控制回路工作原理着手,分析得出分合闸线圈烧毁的根本原因为线圈长时间带电。对此提出了多种改进方法,经过比对确定非接触测量为最优方法。该方法可以在不拆卸操作机构器件、不更改控制回路的条件下完成对分合闸线圈运行情况的监测与评估,实现实时保护及提前预测。

高压SF_(6)断路器零区电弧等离子体调控数值实验研究

为分析高压SF_(6)断路器零区电弧等离子体调控数值,以Eindhoven微观电弧模型为研究对象,探讨不同条件下电弧特性参数的变化。分别针对不同温度、压力及粒子碰撞之间的不同对电弧等离子调控数值进行分析,结果显示随着气压的升高热导率的峰值相应地被推迟到温度较高的区域才出现,并且峰值变小。非平衡态时热导率的变化趋势与平衡态相同,且随着θ的增大,热导率降低。

SF_6断路器操动机构的运行可靠性和选型探讨

本文统计了我国电力系统 1989～ 1997年间 110～5 0 0kVSF6断路器操动机构的故障 ,分析了影响操动机构运行可靠性的因素 ,介绍了SF6断路器开断原理和操动机构的演变和特点 ,提出了提高操动机构可靠性的途径及选用时应注意的问题。

超高压SF_6断路器的智能操作

提出了超高压断路器“智能操作”（即“动触头从一个位置到另一个位置的自适应控制的转换”）的新概念。这是断路器性能智能化的一个重要方面和可行途径。介绍了该智能操作断路器的工作原理。

环境温度及湿度对SF_6断路器中微量水分的影响及控制措施

分析了环境温度及湿度对LW8-40.5型SF6断路器中微量水分的影响及造成该影响的主要原因,进而提出了控制和减小环境温度和湿度对SF6断路器中微量水分影响的措施。

基于光控真空断路器模块串联的126kV三断口真空断路器设计与试验

为将真空断路器应用于更高电压等级,多断口真空断路器的研究成为行业内的热点问题。在分析总结此前研究成果的基础上,设计了一种由3个光控真空断路器模块(FCVIM)串联组成的126 k V真空断路器。断路器按照U形方式串联光控真空断路器模块,光控真空断路器模块主要由外绝缘部件、真空灭弧室、均压电容、永磁操动机构及其控制器和操动电源等部分组成,在低电位通过光纤控制技术对工作于高电位的永磁操动机构进行控制。对三断口真空断路器和单断口真空断路器模块分别施加雷电冲击电压,结果显示三断口真空断路器相对单断口真空断路器的击穿电压增益倍数为1.59;在并联不同均压电容和人为制造三断口不同步分断情况下研究三断口真空断路器暂态电压分布特性,发现低分散性操动机构和均压电容的应用可以有效提高其开断能力。三断口真空断路器在额定电压下成功开断40 k A短路电流,在不同试验方式下完成重合闸操作,并已顺利通过挂网试运行。

关于GIS和SF_6断路器的现场检测方法

本文介绍了GIS和SF6断路器的现场检测方法 ,包括机械振动法、检测管检测法和动态电阻检测法 ,分析了每一种检测方法的原理、适用设备。根据试验中发现的问题和经验 ,提出了抗干扰措施。

国内配电开关设备现状及事故情况

介绍了国内配电电压等级开关设备的现状 ,统计分析了配电开关设备 1990～ 1999年的事故情况以及 SF6开关和真空开关的故障特点 ,指出了无油化是高压开关设备发展的必然趋势。

SF_6断路器灭弧室内三维电场数值模拟

运用有限元法FEM对罐式SF6断路器断口附近三维电场进行了数值计算 ,以计算机辅助绘图为支撑 ,完成了SF6断路器三维电场的数值模拟。在三维电场数学模型的建立中考虑了屏蔽罩和并联电容器组的存在 ;对断路器不同三维剖面的等电位线分布及电场分布情况进行了分析 ;并将计算结果进行三维图形可视化处理及显示。

基于永磁操动机构的光控模块式多断口真空断路器技术

提出了一种设计多断口真空断路器的新思路,即采用基于永磁操动机构的光控模块式真空断路器单元串联成为更高电压等级的多断口真空断路器。它使用光纤控制技术在低电位端对处于高电位的真空断路器的电子操动机构进行控制。最后,对光控真空模块单元中的电源系统进行了介绍。

并联电容器组对高压SF_6断路器内部电场分布的影响

采用模拟电荷法对高压 SF6断路器断口附近复杂三维场域进行了电场计算 ,得到了不同截面等电位线的分布情况及电场分布图。计算结果表明 ,在整个场域中 ,屏蔽罩和并联电容器组起到了很好的均匀电场的作用 ;