Optimal disturbance rejection with zero steady-state error for time-delay large-scale systems with persistent disturbances

This paper considers the optimal control problem for large-scale systems with time-delay under external persistent disturbances. Based on the internal model principle, a compensator is first constructed to cancel the disturbance in the sense of zero steady-state error. The original disturbance rejection problem is transformed into an optimal regulator problem for a composite time-delay large-scale system without disturbances in form. Then, a design scheme is presented to find the optimal control law for the composite time-delay large-scale system by using the series-based approximate approach. A numerical example is applied to demonstrate the proposed design algorithm's effectiveness.