Design and Implementation of a Water Level Controller in Pumping Chamber which is Part of a Wastewater Treatment Plant

This article presents the implementation of a level control system for the drainage pumping station (CBD-01) at the wastewater treatment plant (PTAR) in the city of Cusco, Peru. The control system is based on a PID controller, where the controlled variable is the water level in the pumping chamber, and the manipulated variable is the rotational speed of four pumps, regulated through variable frequency drives (VFD), with the aim of maintaining a constant water level below the overflow point. To achieve this, an OPC connection was established between the PLC and Matlab software, allowing for data acquisition from the open-loop process. Subsequently, the estimated parameters for the PID controller were calculated using the Lambda tuning method, which is suitable for processes with non-self-regulating behavior (integrating processes). The PID controller was implemented in the PLC of the pumping station, and after experimental tests, the controller parameters were adjusted, resulting in final gains of Kc = 15, Ti = 4.5, and Td = 0, with rise and settling times of 70 and 75 seconds, respectively, without significant overshoot or harmful oscillations in the steady state. The results showed a fast and stable response to changes in the setpoint or disturbances in the system.