Proportional-Integral-Derivative (PID) control is the most common control algorithm used in industry. PID controller continuously calculates an error value as the difference between a desired setpoint and a measured process variable. All those control is done by a control valve which contains a positioner. Positioner of the valve is up and down according to requirement.
Here we’ll explain proportional, integral and derivative considering water tank supply and delivery. Delivery of water depends upon production. Production may be increase or decrease anytime depends upon nature.
Where Used?
We can control temperature, pressure, level, flow are common process variables. There is a set value(SV) and present value(PV). PID control system always monitor present value and change the PV according to SV.
Proportional:
Water supplied in tank according to delivery. If delivery of water is 60% then supply water is 60% within this time.
Integral:
When delivery increases from tank then water supply valve positioner also increases. If delivery is 90% then supply increases and goes 90% within this time.
Derivative:
When delivery decreases from tank then water supply valve positioner also decreases. If delivery is 20% then supply decreases and goes 20% within this time.
