Advanced Process Control (APC) is the technology for the (petro)chemical industries that makes it possible to control multivariable control problems. Since these controllers contains the dynamic relationships between variables it can predict in the future how variables will behave. Based on these predictions actions can be taken to maintain variables within their limits.
Normally an APC is connected to a link title(DCS).
Terminology: Manipulated Variables (MVs) are variables where advanced controllers send setpoints to. Controlled Variables (CVs) are variables that normally need to be controlled between limits. Disturbance Variables (DVs) are only used as an input to the controller.