Flexibility refers to the ability to obtain feasible steady-state operation at a given set of operating points. This is a steady-state issue, and we will assume it to be satisfied at the
operating points we consider. It is not considered any further in this paper.
Switchability refers to the ability to go from one operating point to another in an acceptable manner usually with emphasis on feasibility. It is related to other terms such as optimal operation and controllability for large changes, and is not considered explicitly in this paper.
We will assume that the “quality (goodness) of operation” can be quantified in terms of a scalar performance index (objective function) , which should be minimized. For example, can be the operating costs.