Performance analysis of irrigation channels with distributed control

For a string of pools with distant-downstream control, the internal time-delay for water transport from upstream to downstream not only limits the local control performance of regulating water-levels at setpoints and rejecting offtake disturbances in each pool, but also impacts the global performance of managing the water-level error propagation and attenuating the amplification of control actions in the upstream direction. A distributed control scheme which inherits the interconnection structure of the plant is studied. It is shown that the decoupling terms in the controller helps to improve global closed-loop performance by decreasing the low-frequency gain of the closed-loop coupling. Moreover, they compensate for the influence of the time-delay by imposing extra phase lead-lag compensation in the mid-frequency range on the closed-loop coupling function.