Parameterization of All State-Feedback Retrofit Controllers

Retrofit control is a promising approach for distributed design of decentralized sub-controllers for large-scale network systems, while most existing distributed control methods design sub-controllers in a centralized fashion. The key idea of retrofit control is to regard the network system as an interconnected system among a subsystem of interest and the others and to attach a controller that rectifies the effect between the interconnection signals. A parameterization of all retrofit controllers has been already given for the case where interconnection signal can be fed back. Our aim in this paper is to extend the result to the case where interconnection signal is unavailable. We consider state-feedback retrofit controllers without interconnection signal and derive a parmeterization of all state-feedback retrofit controllers. We end with a numerical example demonstrating the effectiveness of retrofit control through a benchmark model representing the bulk power system in the eastern half of Japan.