Interaction assessment in multivariable control systems through causality analysis

Multivariable control systems are continually challenged by the presence of interactions among control loops. The issue of interactions is even more pronounced in systems involving multiloop (decentralized) control schemes. This paper presents a novel method to assess the level of interactions in multivariable control systems. The proposed approach is based on the total directed energy transfer between a pair of variables. The merit of the method lies in its ease of interpretation and versatility in accommodating different controller structures and operating conditions. Further, the method can be applied for both theoretical (when a process model is known) as well as data-driven analysis (when operating data is available). Implementation on synthetic processes are illustrated to demonstrate the usefulness of the proposed approach.