Transient Optimization of the Cryogenic Moderator System Controller at the Spallation Neutron Source for Improved Performance
ORCID
0000-0001-6615-0739 (Liu)
Document Type
Conference Paper
Publication Date
2024
DOI
10.1109/CCTA60707.2024.10666628
Publication Title
2024 IEEE Conference on Control Technology and Applications (CCTA)
Pages
446-451
Conference Name
2024 IEEE Conference on Control Technology and Applications (CCTA), 21-23 August 2024, Newcastle upon Tyne, United Kingdom
Abstract
The high-energy neutron beam generated at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is moderated to use cold (slow) neutrons for scientific discoveries. The Cryogenic Moderator System (CMS) removes heat from the neutron beam using cryogenic hydrogen (H 2 ) moderators connected via heat exchangers to a helium (He) refrigeration loop that dissipates heat using a compressor-brake system. However, the CMS is affected by sporadic losses in beam power, referred to as "beam trips," as these events generate significant disturbances in cooling requirements. To accommodate the heat load transients during beam trips, the CMS uses a decentralized control strategy consisting of four flow valves and one electric heater adjusted by independent proportional-integral (PI) controllers. During the CMS’s initial commissioning, the PI gains were calibrated based only on tracking performance, overlooking their effectiveness in disturbance rejection. A data-driven, control-oriented closed-loop model was developed to recalibrate the PI gains and minimize the transient disturbances caused by beam trips. The model consists of three main components: (1) a physics-based model of the He refrigeration loop, (2) a machine-learning model of the cryogenic H 2 cooling trains, and (3) the control logic used for feedback set-point tracking. Experimental results showed that the recalibrated gains obtained in this study improved the CMS’s transient response during beam trips.
Rights
U. S. Government work not protected by U. S. copyright. Foreign copyright may apply.
Original Publication Citation
Maldonado, B. P., Liu, F., Goth, N., Ramuhalli, P., Howell, M., Maekawa, R., Degraff, B. D., & Cousineau, S. (2024). Transient optimization of the cryogenic moderator system controller at the spallation neutron source for improved performance. In 2024 IEEE Conference on Control Technology and Applications (CCTA) (pp. 446-451). IEEE. https://doi.org/10.1109/CCTA60707.2024.10666628
Repository Citation
Maldonado, B. P., Liu, F., Goth, N., Ramuhalli, P., Howell, M., Maekawa, R., Degraff, B. D., & Cousineau, S. (2024). Transient optimization of the cryogenic moderator system controller at the spallation neutron source for improved performance. In 2024 IEEE Conference on Control Technology and Applications (CCTA) (pp. 446-451). IEEE. https://doi.org/10.1109/CCTA60707.2024.10666628