ABSTRACT
According to the requirement of China’s urban water supply， this paper designs a
set of water supply system of frequecey control of constant voltage based on PLC， and
have developed good operation management interface using Supervision Control and Data
Acquisition.The system is made up of PLC， transducer,units of pumps,pressure sensor
and control machine and so on。
This system is formed by three pump generators，and they form the circulating run
mode of frequency conversion. With general frequency converter realize for three phase
pump generator soft start with frequency control， operation switch adopts the principle
of”start first stop first”。 The detection signal of pressure sensor of hydraulic pressure,via
PLC with set value by carry out PID comparison operation，so，control frequency and the
export voltage of frequency converter,and then the rotational speed that changes pump
generator come to change water supply quantity，eventually，it is nearby to maintain pipe
net pressure to stabilize when set value。 Through work control machine the connection
with PLC,with group form software consummately systematic monitoring,have realized
operation state development to show and data,report to the police inquiry。
Keywords:Variable frequency speed—regulatingConstant-pressure water supplyPLC
