Stability, stabilisation and performance of multilevel controllers under structural perturbations. Part 1: Cutting the links between co-ordinator and subsystems

In this two-part paper we study the stability, stabilisation and performance of hierarchical structures subject to structural perturbations. In this first part, perturbation of the links between the co-ordinator and the subsystems are considered. A sufficient condition is derived for the stability of the resulting controller, and bounds are put on the performance degradation. This condition is tested on the example of a system comprising 11 coupled synchronous machines, where it is seen that verification of the condition when the co-ordination inputs are cut does indeed ensure the stability of the resulting unco-ordinated system.