Virtual control commissioning for a large critical ventilation system: The CMS cavern use case

The current cavern ventilation control system of the CMS experiment at CERN is based on components which are already obsolete: the SCADA system, or close to the end of life: the PLCs. The control system is going to be upgraded during the LHC Long Shutdown 2 (2019-2020) and will be based on the CERN industrial control standard: UNICOS employing WinCC OA as SCADA and Schneider PLCs. Due to the critical nature of the CMS ventilation installation and the short allowed downtime, the approach was to design an environment based on the virtual commissioning of the new control. This solution uses a first principles model of the ventilation system to simulate the real process. The model was developed with the modelling and simulation software EcosimPro. In addition, the current control application of the cavern ventilation will also be re-engineered as it is not completely satisfactory in some transients where many sequences are performed manually and some pressure fluctuations observed could potentially cause issues to the CMS detector. The plant model will also be used to validate new regulation schemes and transient sequences offline in order to ensure a smooth operation in production.