Hello All,

I'm trying to create a pump simulator using TIA Portal version 13.0. I want to test the automatic pump logic that regulated a lead pump, lag 1 pump and lag 2 pump. The pumps are started in order starting from lead and stopped in order starting from lag 2 when all three pumps are in automatic mode. They are stopped and started based on the pressure requirements and deadband of the system. I created the automatic logic without a PID since the pumps only possess one speed. Does anyone have an idea about how I could simulate the automatic pressure logic to see if it maintains the pressure near the desired setpoint?

I tried using a PID for the simulation logic, but the only output is on or off for each pump since they all have one speed. Any ideas are welcomed!

Much Appreciated,

Humble_learnee22

Hi,

From your post what I understood is 3 Pumps are used to build up pressure (say X Units) depending on a pressure set point (SP). And you are in simulation mode, so can't have Process value for pressure (PV).

As all 3 Pumps are of fixed speed, the only option you have is controlling their Run command in the explained manner.

Since we don't know how your process will react and it's dynamics, to keep things simple I propose this algorithm.

1) Process begins (Start of simulation) with predefined SP for Pressure and dead band for Pump startup.

2) PV is not equal to SP

3) Pump1 starts (Add 0.33 in Pressure value with fixed interval, say 1 second). So You should get PV = PV + 0.33 (Linear)

4) PV is still far less than SP hence Pump2 starts (Add 0.33 in Pressure value with fixed interval). Now you should have PV = PV + 0.66 (Linear)

5) PV is still far less than SP hence Pump3 starts (Add 0.33 in Pressure value with fixed interval). Now you should have PV = PV + 0.99 (Linear)

It will take some time to get PV near to SP.

Same way you can simulate reaction of PV when pumps are turned off.

Try to feed this data in your simulation and let us know how it reacts.

Also find attached Excel to see what I mean.

Thank you for the post. I know it has been a while, but I did try your method. However, the pumps are single speed, so the pressure increases by a specific amount and stops and it does this quickly. Therefore, I used an instantaneous change to model the increase and decrease in pressure. Let me know what you think. 

Best,

Humble_learnee22

Hi,

Sorry, but I did not get... Can you explain more

Humble_learnee22

I used an instantaneous change to model the increase and decrease in pressure.