Effect of Bottom Slope on Determining Optimum Coefficients and Performance of PID Controller in Irrigation Canals

Modernization of irrigation canals as an operation improvement tool is essential to promote the performance of canal networks and indeed requires control systems. Proportional integral derivative (PID) algorithms have more applications than the other controllers in different places of the world، but tuning these controllers for different hydraulic conditions of canals is considered as a major problem for designing control algorithms. Since the bottom slope is one of the effective factors in the water flow dynamic behavior، in this research، the distant downstream Proportional Integral Derivative feedback control with decouplers was designed with a change in longitudinal slope in a reference canal and its performance was investigated. The canal characteristics were used to tune this controller and the system identification as a new method was applied for determining canal characteristics. SOBEK hydrodynamic model modulated with MATLAB software was used to design and run the control algorithms، and slope influence on water flow behavior، tuning controller، and coefficients of controller were investigated with different values of slope. Then، controller performance for hypothetical period of operation in various scenarios was evaluated with computation performance indices. The results showed less resonance behavior of water flow and less potential of controller in steep slope