Optimal Distributed Control for Networked Control Systems with Delays

In networked control systems (NCS), sensing and control signals between the plant and controllers are typically transmitted wirelessly. Thus, the time delay plays an important role for the stability of NCS, especially with distributed controllers. In this paper, the optimal control strategy is derived for distributed control networks with time delays. In particular, we form the optimal control problem as a non-cooperative linear quadratic game (LQG). Then, the optimal control strategy of each controller is obtained that is based on the current state and the last control strategies. The proposed optimal distributed controller reduces to some known controllers under certain conditions. Moreover, we illustrate the application of the proposed distributed controller to load frequency control in power grid systems.