基于DCS的EAST低温系统预冷过程自动控制

Automatic control of precooling process in EAST cryogenic system based on DCS

为避免热应力对EAST托卡马克装置的损坏,超导磁体与冷屏的300—80 K预冷过程需要严格控制降温温差;同时低温系统还需提供合适的流量与压降,以保证各冷质部件同步快速降温。通过低温控制流程分析,明确了预冷控制回路与控制需求,设计了预冷操作模式及其顺序控制流程。针对预冷过程中温差-压降耦合问题,设计了分阶段的解耦控制方案。以上控制策略在低温DCS中组态实现,经两轮降温实验运行验证,解耦控制稳定,实现了快速同步降温。预冷过程自动控制取代了持续十几天的预冷手动操作,系统的自动化程度得到了极大提升。

In order to avoid the destruction of heat stress on EAST Tokamak, the cool-down temperature differences of the superconducting magnets and thermal shields during 300-80 K precooling process should be rigorously controlled. Meanwhile, the cryogenic system is required to supply proper mass flow and pressure drop to ensure every cold-mass components cooled-down fast and synchronously. Via analysis of cryogenic control flow, the control loops and requirements were decided, the precooling operation mode as well as its sequence control flow was also designed. Aiming at the coupling control of temperature difference and pressure drop, a grading decoupling control scheme was presented. The control strategy was realized on DCS. Tested by two experiments,the decoupling control was stable and fast - synchronous cool down was realized. The automatic control substituted manual precooling operation lasting over ten days,so the automation degree of the system was highly promoted.