Preventing Control Constraint Violations by Use of Energy Balances for a Class of Coupled Systems: Applied to a Power Plant

In this paper a scheme is presented for preventing violations of control signal constraints in a class of coupled systems. The scheme is an add-on solution to the existing control system; it works like a fault tolerant scheme, by accommodating the problem then occurring. The proposed scheme recomputes the reference values to the system such that control signal constraint violations are avoided. The new reference values are found using an energy balance of the system. The scheme is intended to handle rarely occurring constraint violations, so the only concern is that the system should be stable and not to optimize performance during all conditions. The scheme is applied to an example with a coal mill pulverizing coal for a power plant.