Cascade Control

Hi All,

I would appreciate any advice/input on the below setup and proposal and value any feedback on best methods to achieve the intended outcome (if possible)

Pair of PI controllers, typical cascade loop, level (master) / flow (slave) - only unlike your typical cascade loop the priority is on maintaining a consistent feed flow to a downstream column and allowing the level in the surge vessel to swing. The surge vessels have sufficient capacity that in the event a disruption to the feed flow occurs the level is impacted but slowly. The flow into the vessel does vary only by small amounts during normal operation.

Has anyone successfully implemented a solution like this? was it simply a case of slowing down the level controller?
You have a surge vessel feeding a downstream column. You are controlling a valve position between the surge vessel and the column. Your primary objective is to control the flow into the column. Your secondary objective is to maintain the level in the surge vessel, probably between high and low limits.

Before attempting to answer, is my understanding of the scenario correct?