The paper presents robust design methods for the automatic control of a dam-river system, where the action variable is the upstream flow rate and the controlled variable the downstream flow rate. The system is modeled with a linear model derived analytically from simplified partial derivative equations describing open-channel flow dynamics. Two control methods (pole placement and Smith predictor) are compared in terms of performance and robustness. The pole placement is done on the sampled model, whereas the Smith predictor is based on the continuous model. Robustness is estimated with the use of margins and also with the use of a bound on multiplicative uncertainty taking into account the model errors, due to the nonlinear dynamics of the system. Simulations are carried out on a nonlinear model of the river and performance and robustness of both controllers are compared to the ones of a continuous-time PID controller.
Litrico, X., & Georges, D. (1999). Robust continuous-time and discrete-time flow control of a dam-river system. (II) Controller design. Applied Mathematical Modelling, 23(11), 829–846. https://doi.org/10.1016/S0307-904X(99)00013-X