Variable-frequency speed adjustment technique-based Bang-Bang+PID (Piping and Instrument Diagram) constant pressure water supply closed-loop control method

Abstract

The invention relates to a variable-frequency speed adjustment technique-based Bang-Bang+PID (Piping and Instrument Diagram) constant pressure water supply closed-loop control method, belonging to the technical field of constant pressure water supply control in industrial production. According to the method, a Bang-Bang controller and an error judger are added into a constant pressure water supply closed-loop control system; a controller is judged and selected by sampling a pressure set value and an actual pressure value and by calculating the errors; the output frequency of a frequency changer is adjusted and the rotation speed of a water pump motor is changed through the output of a PID controller or the Bang-Bang controller, so that the constant pressure control to the pressure of the outlet of a water supply pipe net is finally realized. According to the method, the high precision and the high stability of the PID control are combined with the rapidness and the small overshoot of the Bang-Bang control, only one operator is needed to input data in an HMI (Human-Machine Interface) in the whole operation process, the PLC (Programmable Logic Controller) then can automatically select a PID or Bang-Bang control policy according to pressure deviation, therefore, the control precision of the system is ensured, and at the same time the adjusting time of the system is greatly shortened.

Description

technical field [0001] The invention relates to a constant-pressure water supply closed-loop control method based on frequency conversion speed regulation technology, and belongs to the technical field of constant-pressure water supply control in industrial production. Background technique [0002] Constant pressure water supply refers to the water supply mode in which multiple water pumps share the main pipe with the outlet pressure of the pipe network remaining constant when the water consumption in the water supply network system changes. The traditional closed-loop control system of constant pressure water supply consists of figure 1 As shown, the water pump is the final execution unit of the water supply system. The outlet pressure of the water supply pipe network detected by the pressure sensor is used as a feedback signal, and the pressure at the outlet of the water supply pipe network is fed back to the front end of the PID controller through the pressure transmitter...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of long PID controller adjustment time, difficult PID parameter setting, and poor stability of Bang-Bang control in the traditional constant pressure water

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