混合式限流器换流回路的参数优化设计

Parameter Optimization Design of Commutation Circuit of Hybrid Fault Current Limiter

针对10 kV配电网系统的一种传统混合式故障限流器进行了仿真研究,该限流器由主回路的快速开关及换流回路组成,换流回路由预充电电容及电感和晶闸管组成。研究结果表明在限流的过程中,快速开关两端的恢复电压上升速率及峰值大小与换流回路各器件的参数有很大的关系。若参数匹配不当,则存在开关被重击穿的可能性。文中介绍了在开关两端并联晶闸管的改进型方案,当开关中的短路电流过零后,该晶闸管会起到续流作用,以保证开关存在利于介质恢复的低电压时间。通过理论分析发现,该低电压时间值的长短受换流回路的电容电感参数影响较大,具体研究了低电压时间与这些参数的变化关系,并通过低压模拟实验验证了关系的正确性。在实际的快速开关设计中,可通过调节这些参数来得到合适的低电压时间值,从而减小对开关机构速度及断口介质击穿强度特性的要求。

The simulation of a traditional type of hybrid fault current limiter applied in 10 kV distribution network system is studied,which is composed of a fast switch in the main circuit,a pre-charging capacitor in series with an inductor and thyristors in the commutation circuit. The result shows that the rise rate and peak value of the recovery voltage of the fast switch have much to do with the parameters of devices in the commutation circuit. If these parameters have a bad collocation,the fast switch will have a breakdown. An improved topology—a thyristor in parallel with the fast switch is described. When the current of fast switch becomes zero,the thyristor will play a role of conducting the current,so the voltage across the switch will be clamped at a low value for a time called low voltage time. By theoretical analysis,it is found that the capacitor and inductor in the commutation circuit exert great influence on the length of the low voltage time and their relationship is studied in particular. By the low voltage experiment,the relationship is tested and verified. For the design of the fast switch,an appropriate length of low voltage time can be obtained by adjusting these parameters to reduce the requirements for the opening speed and dielectric recovery of the fast switch.