Tank Level Control Using PID

To maintain tank level: " Flow In" must equal "Flow Out"

Not enough information.

Why do you want to complicate this?

Where does tank overflow (drain valve?) go now?

How precise does tank level control need to be?

Can you post a schematic of the system, with a description of the process?

Existing or proposed or homework?

As Lyn said, need more information. What is the bypass for? Are you pumping into or out of the tank? Does your PLC have a PID function? Please post a flow sketch of what you're trying to do. It's certainly doable - you/we have to know exactly what you're trying to accomplish.

Typical. I hear crickets chirping in the quiet, ya'll scared the OP off with these nonsensical question of yours.

He knows what he wants why don't you?

Sorry for not being more clear. Let me make it narrow.

There is only 2 tank (120 liter/each ): one is upper -T1 the second is lower level tank -T2. The water is being pumped from lower level to the upper level with variable speed pump. I need to control water level on upper tank using PID controlled pump speed (using PID in PLC).

For example, assigning 10 liter/min or 20liter/min etc

I want to able to maintain the level at certain set points 10cm-20cm-30cm..100cm as well.

there is a level transmitter installed on Tank (T1).

The idea here is to learn how to apply PID control in PLC to this kind of application by controlling certain parameters like speed of pump, or drain valve position (%20, %30.. open). Assume transmitters are all connected. I am using Pro Suite.

Here is some reading for you...

http://www.controlguru.com/2007/070607.html

well well well.

first thing first.

you want to control tank level??, fine you must make the control-loop between pump RPM or pump % velocity and water level

you can do this in other way, run your Pump at fix speed and install an automatic valve, in this case the control - loop is between valve position and water level.

because you just need to control tank level, controlling flow is pointless

you forgot one thing, you gotta control lower tank as well.

in the end is an easy control loop, have fun.

Looks like someone doesn't want to do the research for their homework!

You only cheat yourself by having someone else do your learning for you.

No-one needs PID on tank level control. The purpose of a tank is to let the level go up and down. If you need fixed level, then get rid of the tank and use a weir instead.