Linear Quadratic Optimal Controller Design for Constant Downstream Water-Level PI Feedback Control of Open-Canal Systems

State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, 430072 Wuhan, China

^* Corresponding author:
^a Guan Guanghua: GGH@whu.edu.cn

Abstract

The key point of PI feedback control is how to design appropriate controller parameters. This paper combined the linear quadratic optimizing control theory to design an online controller for constant downstream water-level operation which could respond to different working condition properly and rapidly avoiding complex controller parameters adjusting. Based on the Integrator-Delay (ID) model simplified from Saint-Venant Equations, we established the discretized linear time invariant system of canals. Then transferred it into the state-space equations and obtained the state-feedback equation. Water level deviations and flow rate increments were chosen to form the objective function and this paper recommended values of Q and R weight matrices among it should be set according to the optimum quadratic form indicators correspondingly. This controller was applied to two practical canal systems which had diverse scales. Results showed the system under control quickly regained stability; optimizing the objective function with recommended weight matrices could well balance demands on water level deviations and flow rate changes; dynamic performances of water movements and gate movements were acceptable. Through simulations, we preliminarily proved the practicability of this online PI controller implementing LQR. This work proposed an available solutions for the design and operation of water conveyance systems around the world.