真空直流强迫分断零区弧后电流特性及其控制方法研究

The post-arc current is an important part of circuit breaker’s current-zero characteristics, which influence the breaking capacity of breakers. Studying the post-arc current is useful for improving the arc model of current-zero, enriching the theory of vacuum DC arc. Nowadays, the investigations on the current-zero characteristics mainly focus on the simulation of sheath growth and measurement of dielectric strength. Few works were done on the characteristics of post-arc current. In this project, the investigations focus on the characteristics of post-arc current for different dynamic factors, such as opening speed, commutating frequency, current amplitude and so on. By the study, the relationship between the post-arc current and breaking capacity is revealed and the critical post-arc current is obtained. It provides a flesh evidence to judge the breaking capacity of vacuum DC circuit breakers. In addition, the control method is put forward to optimize the post-arc current characteristics and improve the breaking capacity. The results can be used to judge that whether the breakers have achieved its limitation, improve the breaking capacity and guide the design of vacuum interrupters for vacuum DC interruption in future.

弧后电流是断路器零区物理特性的重要研究内容之一，研究弧后电流特性可完善零区真空电弧模型，丰富直流真空电弧理论，提高直流断路器开断能力，具有重要的科学意义。目前针对零区特性的研究多侧重于鞘层增长过程的仿真及弧后介质强度测量，而对零区弧后电流特性的研究相对较少。本项目侧重于研究不同动态影响因素(如分断速度、电流幅值、换流频率、燃弧时间、恢复电压上升率等)下的弧后电流特性，揭示弧后电流与直流断路器开断能力之间的影响关系，得到开断极限对应的弧后电流临界值，给出新的直流断路器开断极限判据。最后通过合理的控制方法，优化弧后电流特性，提高真空直流断路器的开断能力。研究成果可用于判断直流断路器是否达到开断极限，并提高其开断性能，为未来真空直流强迫分断用灭弧室设计奠定理论和试验基础。

弧后电流是断路器零区物理特性的重要研究内容之一，弄清直流开断后零区弧后电流特性，对完善零区真空电弧模型，丰富直流真空电弧理论，具有重要的意义。首先，本项目建立了电路与等离子体电弧的耦合模型，开展了不同分断速度、燃弧时间、换流频率等动态因素下的零区弧后电流特性研究，仿真得到了上述参数对零区弧后电流特性的影响。其次，改进了弧后电流测量装置，搭建了直流开断用合成回路系统，测量了不同分断速度、燃弧时间、换流频率等动态因素下的弧后电流，实验得到了弧后电流临界值及最佳分断参数。最后，设计了一种横磁-纵磁组合式触头结构，拟通过改变断路器开断过程及开断完成后电极间隙中的磁场分布来改变电弧等离子分布，从而提高断路器分断能力。研究结果可用于完善真空直流零区电弧模型，指导判断直流断路器开断能力，为设计真空直流强迫分断用灭弧室奠定理论依据和试验基础。