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Paper details
Number 2 - June 2022
Volume 32 - 2022
Reliability-aware zonotopic tube-based model predictive control of a drinking water network
Boutrous Khoury, Fatiha Nejjari, Vicenç Puig
Abstract
A robust economic model predictive control approach that takes into account the reliability of actuators in a network is
presented for the control of a drinking water network in the presence of uncertainties in the forecasted demands required for
the predictive control design. The uncertain forecasted demand on the nominal MPC may make the optimization process
intractable or, to a lesser extent, degrade the controller performance. Thus, the uncertainty on demand is taken into account
and considered unknown but bounded in a zonotopic set. Based on this uncertainty description, a robust MPC is formulated
to ensure robust constraint satisfaction, performance, stability as well as recursive feasibility through the formulation of
an online tube-based MPC and an accompanying appropriate terminal set. Reliability is then modelled based on Bayesian
networks, such that the resulting nonlinear function accommodated in the optimization setup is presented in a pseudo-linear
form by means of a linear parameter varying representation, mitigating any additional computational expense thanks to the
formulation as a quadratic optimization problem. With the inclusion of a reliability index to the economic dominant cost of
the MPC, the network users’ requirements are met whilst ensuring improved reliability, therefore decreasing short and long
term operational costs for water utility operators. Capabilities of the designed controller are demonstrated with simulated
scenarios on the Barcelona drinking water network.
Keywords
fault-tolerant control, reliability, robust MPC, zonotopes, Bayesian theory, drinking water network