A two-level hybrid control strategy for the start-up of a coupled distillation plant

In this contribution, we suggest an efficient hierarchical hybrid control scheme for the start-up of a distillation plant consisting of two coupled distillation columns. The overall control task is decomposed into a set of low-level and high-level subtasks. Each of these subtasks can be solved with much less effort than the original specifications. Low-level tasks are solved by means of continuous feedback, whereas the high-level task is solved by a discrete supervisory controller operating on quantised measurement information and switching between continuous low-level controllers. The approach presented is set within a behavioural framework; it guarantees that the chosen interaction of low-level and high-level control does indeed enforce the specifications.