摘要
直流塑壳断路器广泛应用于直流配电网中,随着开断容量的提升,大电流开断下的飞弧现象时有发生,对设备和人身安全造成隐患。该文通过实验研究恒定驱弧磁场作用下塑壳断路器在不同开断电流下的电弧运动过程,利用高速摄像机拍摄捕捉到大电流开断过程中的飞弧现象。基于磁流体动力学理论,建立考虑阿基米德力(浮力)的改进电弧磁流体动力学(MHD)模型,对飞弧现象进行数值分析,发现在塑壳断路器灭弧室中,高温电弧导致跑弧道拐角处产生反向气流涡旋将抑制弧柱向上运动,高能量电弧所受浮力无法充分发挥,导致上半部电弧无法进入栅片,栅片利用率低,下半部电弧由于能量较大,进入栅片后飞出,造成飞弧现象;另外由于大能量电弧所受洛伦兹力较大,电弧被切割后与栅片进行热量交换时间短暂,无法及时散热,运行至栅片尾部的电弧仍具有较高能量,易飞出栅片产生飞弧现象。根据仿真结果,采用双出气口结构灭弧室,改变气流场分布,减小了气流漩涡,充分发挥大能量电弧浮力作用,提高栅片的利用率;采用改进绝缘产气栅片,限制弧根的运动速度,增加灭弧室内栅片与电弧的热交换时间,减小飞弧能量。通过实验与仿真对改进灭弧室进行分析,验证其合理性,对两种抑制措施进行结构优化,得到两种改进结构下的最优解。结果表明,两种措施在一定程度上抑制了飞弧现象的发生,有利于电弧的开断。
With the continuous development of the domestic photovoltaic industry,DC distribution technology is becoming increasingly sophisticated,and the capacity of DC transmission is increasing,which leads to stricter requirements for the switchgear used in DC transmission.A DC-molded case circuit breaker(DCMCCB),as a protection device in the photovoltaic power generation system,is mainly installed in the DC combiner box and DC distribution cabinet to provide over-current and isolation protection for the circuit.Most of the DCMCCB used are improved by AC molded case circuit breakers(AC-MCCB).In actual operation,when the current breaking level is too large,an arc-over phenomenon is likely to occur.Therefore,restraining the arc-over phenomenon has become an urgent problem.According to the actual product,the experiment platform of the arc chamber is built.The arc flies out of the arc chamber when the arc with a high current is broken under a constant magnetic field.A magnetohydrodynamic(MHD)model is established considering the arc's Archimedean force(buoyancy),and the arc-over phenomenon is analyzed.The causes of the arc-over phenomenon are as follows:(1)The structure of the arc chamber causes the reverse airflow vortex at the corner of the arc runner to inhibit the upward extension of the arc column,and the buoyancy of high energy arc cannot play its full role.As a result,the arc column enters the splitter plates in advance,and the utilization rate of splitter plates decreases.The lower part of the arc rapidly flies out of the splitter plates under the action of strong Lorentz force.(2)Due to the large Lorentz force of the high-energy arc,the heat exchange time between the arc and the splitter plates is short after the arc is cut,and the heat cannot dissipate timely.The arc running to the tail of the splitter plates still has high energy,and it is easy to fly out of the splitter plates.Therefore,a reasonable arc chamber structure should be adopted to improve the arc moving speed in the longitudinal direction and the utilization rate of splitter plates.In addition,the motion speed of the arc root on the splitter plates should be reduced,or the motion of the arc root on the splitter plates should be limited,and the heat exchange time between the arc energy and the splitter plates should be increased.Thus,the arc energy can completely escape in the arc chamber.According to the numerical simulation results,this paper proposes two improved measures to suppress the arc-over phenomenon.(1)The double air outlet structure,by changing the airflow field distribution,weakens the reverse airflow vortex and improves the splitter plate utilization.(2)The improved insulation grid limits the motion speed of the arc root,increases the heat exchange time between the splitter plates and the arc in the arc chamber,and reduces the arc-over energy.The improved structure is checked by high current breaking to verify the improved structure,and the two structures are optimized.
作者
李静
高万瑞
段薇
刘树鑫
于龙滨
Li Jing;Gao Wanrui;Duan Wei;Liu Shuxin;Yu Longbin(Key Lab of Special Electric Machine and High Voltage Apparatus,School of Electrical Engineering Shenyang University of Technology,Shenyang,110870 China;State Grid Liaoning Electric Power Research Institute,Shenyang,110006,China)
出处
《电工技术学报》
北大核心
2025年第19期6329-6341,共13页
Transactions of China Electrotechnical Society
基金
国家自然科学基金项目(51407120)
辽宁省教育厅面上项目(LJKZ0126)资助。
关键词
直流塑壳断路器
飞弧
阿基米德力
改进MHD模型
飞弧抑制
DC molded case circuit breaker(DCMCCB)
arc-over
Archimedes force
improved MHD model
curb arc-over
