电工技术学报  2024, Vol. 39 Issue (22): 7278-7290    DOI: 10.19595/j.cnki.1000-6753.tces.231597
高电压与放电 |
基于改进结构的自激式直流空气断路器小电流开断能力提升方法
李静, 郭沛鑫, 彭世东, 段薇, 曹云东
沈阳工业大学特种电机与高压电器教育部重点实验室 沈阳 110870
Enhance Small Current Breaking Performance of Self-Excited DC Air Circuit Breaker Based on An Improved Structure
Li Jing, Guo Peixin, Peng Shidong, Duan Wei, Cao Yundong
Key Lab of Special Electric Machine and High Voltage Apparatus Shenyang University of Technology Shenyang 110870 China
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摘要 大容量自激式直流空气断路器(SE-DCCB)广泛应用于轨道交通电力系统中,其可以快速切断大等级短路电流。但是SE-DCCB分断几百安小电流时自激磁场较小,导致电弧燃弧时间较长甚至开断失败。该文通过耦合自激线圈磁场的改进磁流体动力学(MHD)模型,仿真得出双气流涡旋和弧根黏滞是SE-DCCB开断小电流失败的主要原因。为了提高SE-DCCB开断小电流的能力,对其结构进行改进,改进结构SE-DCCB采用安装导磁条的导磁板,并减小跑弧道转弯角半径,可以加快弧根运动速度、削弱小电流开断时的双气流涡旋和弧根黏滞现象,从而缩短燃弧时间。同时,改进结构SE-DCCB降低了电弧熄灭时刻灭弧室入口处的温度,能够减小电弧熄灭后重燃的概率,提升其开断小电流的性能。该研究揭示了SE-DCCB小电流难以开断的物理本质,可为轨道交通用空气断路器提供研发指导。
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李静
郭沛鑫
彭世东
段薇
曹云东
关键词 自激式直流空气断路器(SE-DCCB)小电流结构改进双气流涡旋弧根黏滞    
Abstract:With the development of urban rail transit in China, the performance of self-excited direct current air circuit breaker (SE-DCCB), which plays the protective function, has been put forward higher requirements. Series excitation is used in the SE-DCCB to generate a magnetic field to drive the arc into the arc chamber. Thus, bi-directional breaking can be realized. However, when the equipment on the electric locomotive is in the standby state, the train is in the working state of a small current, which cannot generate enough self-excited magnetic field to drive the arc into the arc chamber. The arc fails to be extinguished in time, endangering rail transit's reliability. Improving the performance of SE-DCCB in breaking small current arcs has become an urgent problem.
A magneto-hydro-dynamic (MHD) arc model coupled with a three-dimensional self-excited magnetic field of the SE-DCCB is established. The sheath is processed precisely so that the effect of space charge near the electrode on the arc can be simulated accurately in the model. Taking SE-DCCB breaking 300 A small current as an example, the arc morphology, magnetic field strength, temperature field, and airflow field in the arc chamber are analyzed, and the main reasons for the difficulty in small current breaking in SE-DCCB are explored. During the breaking process of SE-DCCB, the arc root sticks to the arc runner's turning angle, making it difficult to move along both sides of the arc runner, and the utilization rate of splitter plates is reduced. In addition, the double airflow vortices generated at the entrance of the arc chamber make the arc tailing, resulting in a high temperature at the entrance of the arc chamber, and the possibility of arc re-strike is increased.
This paper proposes an improved structure of SE-DCCB by simulation analysis. The magnetic conductance strip is installed on the magnetic conductance plate, and the turning radius of the arc running path is reduced. The improved structure of SE-DCCB can speed up arc root motion, increase arc ductility, reduce the adverse factors affecting the small current arc extinction, and shorten the arc burning time. Meanwhile, it can effectively reduce the inlet temperature of the arc extinguishing chamber and reduce the reignition probability after the arc is extinguished.
Through simulation analysis, the following conclusions are drawn. (1) In the process of small current breaking, the arc root of SE-DCCB is easy to stop at the turning angle of the arc runner, and the double airflow vortices at the entrance of the arc chamber cause the arc tailing phenomenon, which is challenging makes it difficult for small current breaking of SE-DCCB. (2) The magnetic field strength and distribution above the arc runner affect the viscosity of arc roots. The improved magnetic conductivity structure can enhance such magnetic field strength without changing the excited current. As a result, the arc roots move farther to both sides along the arc runner, and the arc is elongated, facilitating the arc extinguishing with a small current. (3) Reducing the turning radius of the SE-DCCB arc runner can inhibit the generation of double airflow vortices at the entrance of the arc chamber, thus weakening the arc root tailing phenomenon and eliminating the potential arc reignition and breaking failure problems.
The improved model established in this paper can accurately predict arc behaviors in the self-excited field of SE-DCCB, which provides a practical way to optimize the small current arc extinguishing performance of SE-DCCB.
Key wordsSelf-excited DC air circuit breaker(SE-DCCB)    small current    structure improvement    double airflow vortices    arc root stagnation   
收稿日期: 2023-09-27     
PACS: TM561.5  
基金资助:国家自然科学基金项目(51977132)和辽宁省教育厅面上项目(LJKZ0126)资助
通讯作者: 彭世东 男,1997年生,博士研究生,研究方向为电弧放电等离子体、直流开断技术。E-mail: pengshidong@hotmail.com   
作者简介: 李 静 女,1977年生,博士,教授,博士生导师,研究方向为微观电器电弧理论、高电压与绝缘技术。E-mail: lijing@sut.edu.cn
引用本文:   
李静, 郭沛鑫, 彭世东, 段薇, 曹云东. 基于改进结构的自激式直流空气断路器小电流开断能力提升方法[J]. 电工技术学报, 2024, 39(22): 7278-7290. Li Jing, Guo Peixin, Peng Shidong, Duan Wei, Cao Yundong. Enhance Small Current Breaking Performance of Self-Excited DC Air Circuit Breaker Based on An Improved Structure. Transactions of China Electrotechnical Society, 2024, 39(22): 7278-7290.
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