Design of control system of coagulant dosing based on PLC

The paper introduced principle, control strategy, hardware constitution and software design of a control system of coagulant dosing based on PLC in details. The control system takes light transmittance pulsation measurement value as control factor, adopts cascade control method of double PID controllers to realize the optimum control of coagulant dosing amount. Meanwhile the system introduces flow ratio feedforward control, so as to ensure the stability of water turbidity.