Stability and performance analysis of an irrigation channel with distributed control

For a string of pools with distant-downstream control, the internal time-delay for water transport from upstream to downstream does not only limit 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 that inherits the interconnection structure of the plant is investigated. It is shown that the decoupling terms in the controller help to improve global closed-loop performance by decreasing the low-frequency gain of the closed-loop coupling. Moreover, the decoupling terms 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.

► The internal time-delay impacts on local and global performance of channel control are analyzed.
► A distributed control scheme that inherits the structure of a channel is investigated.
► The decoupling terms in the controller compensate for the influence of the internal time-delay.