【作者】 芦娜；

【导师】 许良军； 章继高；

【作者基本信息】 北京邮电大学 ， 电路与系统， 2009， 博士

【摘要】 电力系统中,大容量的输配电设备在短路情况下产生很大的电动力,对电器的性能和结构影响极大。断路器的接触系统,在短路或触头闭合情况下涌浪电流通过时由于电流收缩形成回路而产生的强大电动斥力作用,触头的接触压力显著减小,可能引起触点弹跳,导致接触表面金属挥发,产生电弧,造成触头的熔化或熔焊。从而影响触头正常工作或引起重大事故。电流越大,产生的电动斥力越大。因此,这一问题特别是对结构紧凑的低压真空断路器尤为重要。为了避免设备短路或触头闭合情况下涌浪电流通过时引起的触点的弹跳,抑制触头的电动斥力,本文利用电磁力的作用原理,设计了一种与触头柔性连接的特殊装置,根据负载电流对触点的接触压力进行动态补偿。电磁力的产生,是通过具有一定的时空分布特性的电磁场来实现的。因此,对断路器电接触在线补偿装置的电磁场的分析和计算是非常重要的。本论文的主要内容是关于断路器电接触在线补偿装置的电磁场分析及优化设计。论文分析了断路器电接触系统在短时短路、开关闭合和断开时的电动稳定性。提出了断路器电接触在线补偿方案,并以WP630-1.2型低压真空断路器为研究对象进行在线补偿设计。从电磁场的基本原理出发,通过麦克斯韦方程组推导了用有限元法计算电磁场分布的微分方程并利用有限元软件对WP630-1.2型低压真空断路器的在线补偿系统进行电磁场分析和电磁力的计算。在此基础上,对断路器接触补偿系统电动力的影响因素进行研究,分析了不同结构的补偿系统的磁场分布,给出了在线补偿系统电动力与负载电流、结构形状、几何参数的关系及计算公式。以上研究为补偿系统的的参数优化设计提供了依据。论文通过应用电位-温度理论、金属传导理论中的Wiedemann-Franz定律、牛顿公式、热平衡方程对WP630-1.2型低压真空断路器的电接触及其在线补偿系统进行了正常稳态、短路暂态运行情况下的热分析,结果证明了断路器电接触及补偿系统在正常运行时及短时短路浪涌电流通过时的温升没有超过其极限允许温度,具有良好的热稳定性。论文的另一部分工作是利用ANSYS的APDL模块,基于VB编程平台,开发了有限元模拟可视化软件。在磁场力、热分析的基础上对补偿系统进行参数优化设计,得到各个参数对磁场力的影响,建立了在一定约束限制下,以电磁力为目标的参数可视优化设计的数学模型。为结构设计与分析提供了新的途径和方法。论文通过对真空断路器的电接触在线补偿系统的理论分析、计算及实验研究,证明了在线补偿系统对抑制真空断路器接触系统闭合时触头的弹跳,减小闭合触点间的动态电阻,加快触点断开速度,有效提高其分断可靠性及开断能力,抵抗瞬时浪涌电流有重大意义。更多还原

【Abstract】 Great capability transmitting and distributing electricity equipments bring powerful electrodynamic force under short circuit conditions during power transmission. The high repulsive force value between contact members due to current path shrink arising mostly at contact closure and/or in transient under short circuit conditions is particularly onerous for power switch applications. It results in the contact force value between contact members dropping obviously and either contact floating or bouncing which are associated with an electric arc and following contact welding, which affect the transporting and distributing electricity equipments normal running. Higher is the current value higher is probability of a contact repulsive. Therefore, this problem is of great importance for any circuit breaker especially for vacuum circuit breakers of a low voltage which are of a compact structure.To avoid the contact floating or bouncing at closure and during any inrush current under short circuit conditions, a special compensation system flexibly combined with the contact itself has been developed, which employs an electromagnetic effect of the contact load itself based on electromagnetic force mechanism. However the electromagnetic force is generated by electromegnetic field with a certain form and distributing characteristic. It is necessary to analyse and calculate the electromegnetic field of the electric contact compensation system on line of circuit breaker.The content of this thesis is about the electromegnetic force analysis and optimization design of the electric contact compensation system on line of circuit breaker.In this thesis, electromagnetic field differential equation is derived from the basic electromagnetic field principle-Maxwell equation group. The electromegnetic force analysis of the electric contact compensation system on line of circuit breaker is carried out using Finite Element Method (FEM), and comparing with the analytic method results. The different shape and different geometrical parameter compensation system effecting on electromagnetic force value and distributing are analyzed. Curve-fitting and Equations of electromagnetic force as the function of shape, geometrical parameter and load of the compensation system are given according to the calculating results, the optimization designing of compensation unit is based on it.Besides, Potential-temperature theory, Wiedemann-Franz law in metal conduction theory, Newton formula and thermal balance Equation are used respectively for thermal calculating of the electric contact and compensation system on line of circuit breaker under steady and transient state. Favourable thermal steady performances of them are proved.Another part of this thesis is that the visualized finite element simulation software was developed based on VB programming platform using ANSYS-APDL module. Furthermore, parameter optimization design of the compensation system was carried through based on thermal and electromagnetic force analysis. A visualized parametic model is established under certain constraints, which provide the engineers with new track and method to design and analyze structures in future.The circuit breaker performance can be improved significantly by theory analysis, calculation and experiment investigation for on-line contact compensation. The contact rebounds under closure are suppressed and the dynamic resistance of the closed contacts under short circuit conditions is found even to be decreased. Due to the reverse threshold of the compensator under operation the speed of contacts at opening is increased what increases the breaking ability of the switch.更多还原