Dynamic simulation of warm compressor station for SHINE test facility cryoplant

Abstract

To fulfill the cooling capacity needs of cryomodule test facility for the Shanghai high repetition rate x-ray free electron laser (XFEL) and extreme light facility (SHINE), a 1 kW@2 K helium cryoplant has been implemented. The helium cryoplant comprises a warm compressor station and a cold box, where the former ensures a consistent supply of high-pressure helium to the latter. Normally, a proportional integral (PI) controller is employed to regulate both high-pressure and low-pressure levels in the compressor station, thereby ensuring stable operation of the cold box. However, under certain circumstances such as cold box turbine shutdown, both high-pressure and low-pressure can experience significant fluctuations, thereby posing a risk of severe safety accidents. Hence, it is imperative to conduct tests on pressure fluctuations in the aforementioned conditions. Due to the risks associated with conducting failure condition experiments, a dynamic simulation model of the warm compressor station was developed using EcosimPro software to perform failure testing. The simulation results of the compressor start process are compared with experimental data to validate the accuracy of the dynamic model. Subsequently, simulations of the valve fail open, turbine shutdown, and heat load shock conditions are conducted. Fuzzy PI (FPI) control is introduced to cope with fault conditions. The simulation results have verified the effectiveness of FPI control over conventional PI control, which can reduce maximum high pressure (HP) and recovery time under fault conditions.