Multistate PLS for continuous processes

Batch process monitoring methods, such as multiway PCA and multiblock multiway PLS, make use of time profiles to define expected process variable trajectories for statistical process control. Nevertheless, continuous process counterpart methods of desired process variable profiles have not been developed, nor addressed in the literature. This work presents a novel methodology to define multiple operating points around which continuous processes operate. Process operating regions are divided into multiple states of operation and shifts in operating conditions are captured by special variables, named state variables. Transition trajectories between states are calculated to determine the most likely path between states. This methodology can be implemented in the context of empirical monitoring methods, named Multistate PLS. A case study shows how this methodology enhances fault diagnostics and statistical monitoring of continuous processes.