Simplified design approach for decentralised controllers of large-scale systems

In the design of decentralised controllers of large-scale systems, the performance of the system is not usually good enough, sometimes the system may be unstable if all the interactions between the subsystems are neglected, while the solution of a problem of high dimension (equal to the order of the whole system) is met if the interactions are considered fully. A simplified approach is proposed here, i.e. the decentralised controller of a subsystem is designed using the reduced-order model for the rest of the system. In other words, the subsystem and the reduced-order model are taken to comprise an approximated low-order system, on which the decentralised controller for the subsystem is designed. The balanced model reduction method and gradient optimisation technique are used in the paper. And it is shown that the approach could greatly simplify the design of decentralised controllers for high-dimension systems and achieve high performance.