Influence of PI controller setting parameters on the quality of pressure control in a water supply system with a variable-frequency pump drive

The study is devoted to the problem of optimizing the parameters of the proportional-integral pressure controller in water supply systems. The theoretical basis of the work is the provisions of the theory of automatic control, from which it follows that the proportional component Kp ensures a quick response to deviations of the controlled variable, and the integral KI - smooth elimination of the static error. The effect of the PI controller setting parameters on the control time and the amplitude of pressure oscillations was experimentally studied. A laboratory setup with a centrifugal pump, a frequency converter and a data acquisition system was used. The results showed that the choice of controller parameters significantly affects the quality of transient processes. It was found that at KI < 1 the controller does not provide pressure stabilization, and at Kp - 1 and Ki < 5 the control time increases significantly. The minimum amplitude of pressure oscillations is achieved at 2 ≤ Kp ≤ 3, and the dependence on KI turned out to be weakly expressed. Optimum parameters correspond to Kp = 2.5–3 and KI = 10, providing minimum control time and amplitude of pressure oscillations.