Water level predictive control in multi-cascade pools with large control interval demand based on constraint methods

•The control interval constraint method can increase the control interval of MPC.•The water level constraint method can avoid unnecessary control of minor deviations.•The simultaneous use of the two methods can greatly reduce the gate control times. Model predictive control (MPC) is an effective real-time control method in dealing with water level deviations in canal pools. However, the control interval must be relatively small if some canal pools have short time delay characteristics, resulting in frequent gate control and limited use in practical engineering. In this paper, control interval constraint and water level soft constraint methods were proposed to handle frequent gate control problems in MPC. The MPC method with these constraint methods was tested on a simulation model of the Beijing–Shijiazhuang part of the Middle Route of the South-to-North Water Diversion Project (MRP) with two kinds of disturbances common to this project. The results indicate that the control interval constraint can increase the gate control interval and avoid back-and-forth gate opening adjustments without affecting the water level regulation. The water level constraint helps avoid unnecessary control to minor water level deviations. With both constraints used together, the control times can be reduced by 60% and 37%, respectively, in the two test disturbances. This control method meets the demand of large control intervals in multi-cascade pools.