Cleanrooms pressure cascade: standard PID-based solutions and step forward to MIMO control

This paper gives in-depth analysis of the cleanrooms pressure cascade problem, where the starting point is the state-of-the-art control practice for stabilization and disturbance rejection of static pressure and air-flow rate. The plant components are modeled in order to obtain multivariable model of a typical plant in the context of heating-ventilation-air conditioning (HVAC) and variable-air-volume (VAV) based cascade control. Opposed to the standard control solutions realized by the independent PID loops, presented multivariable modelling enables the proper analysis and effective high-performance solutions of the control for the plants with observed strong internal couplings. The results and problems arising from the state-of-the-art control practice in pharmaceutical factories in the Republic of Serbia is given in a case study, and the open issues are highlighted.