Reference:
A. Sadowska,
B. De Schutter, and
P.-J. van Overloop,
"Delivery-oriented hierarchical predictive control of an irrigation
canal: Event-driven versus time-driven approaches," IEEE
Transactions on Control Systems Technology, vol. 23, no. 5, pp.
1701-1716, 2015.
Abstract:
In this paper we present the concept of a hierarchical predictive
controller used for irrigation canals. The motivation behind the work
is the need in the field of irrigation to deliver water to farmers
fast, but with minimal resources involved as the communication links
in the field are not dependable in practice. In response to such a
control problem we propose a hierarchical controller: the lower
control layer is formed by decentralized PI controllers and the higher
control layer is constituted by a centralized predictive controller
the purpose of which is to control the inflow to the canal and,
importantly, to coordinate the local controllers by modifying their
setpoints. Having in mind the restrictions on the available
communication infrastructure and the control equipment already
present, the scheme is designed to be event-driven, i.e. activated
when there are either delivery requests or non-delivery-related events
of any sort, requiring special care on top of the control provided by
the PI controllers. We also study a time-driven formulation with an
additional post-processing step to avoid excessive negligible setpoint
modifications. We compare the event-driven formulation and the
time-driven formulation theoretically as well as by means of a
simulation study for the West-M irrigation canal in Phoenix, Arizona,
illustrating the findings of the paper. It is shown that the
event-driven controller is able to provide a good balance between the
control performance and the required update frequency of the control
settings.