Clicking on the below download button to download an executable SCADA software file that will run an interactive demo of a realistic simple non-linear level control system. You can adjust the plant conditions and controller settings and observe the responses in graphical form.
Note: some antivirus softwares may require you to ‘accept’ the download of this executable file.
Demo of a SCADA
Features of SCADA Software
- Users can adjust PID controller settings and Set Point.”
- User-adjustable Manual Control output.
- User-adjustable System Load.
- Model of the tank being filled with liquid from a pump via a control valve.
- Using the typical characteristics of a fixed speed pump and a typical control valve characteristic.
Valve has 0.3% leakage when “Shut”.
- The location of the working points on the pump curve and valve curve is illustrated.
- Second-order lag introduced into line to control valve to make performance more realistic.
- The tank outlet flow can be altered by a second valve to demonstrate the application of different loads to the system.
- The tank outlet flow is a function of pressure drop across the outlet valve.
The pressure drop across the outlet valve is a function of tank level plus fixed head (350) down the outlet pipe.
- When the tank is empty the outlet flow is equal to the inlet flow.
- When the tank is full the tank overflows.
- A controller is PID where the derivative term only responds to the measured variable, eliminating excessive action from SetPoint step changes.
- Gain adjustment 0 to 10, Integral adjustment 0.1 to 49.9 secs plus “Off”, derivative adjustment 0 to 10 secs.
- Bumpless Transfer:
- when in Manual, the Controller balances its output against valve demand by adjusting integral term initial condition.
- When in Auto controller output is limited to 0 to 100%.
- Anti-integral wind-up:
- when at limit further integral action is inhibited unless tendency is to bring controller out of limit.
- System performance is displayed on trend graph: Thin lines are controller internal values, thick lines are external (plant) values, pen colors match signal lines on the plant diagram.
- All trend values are 0 to 100% except some controller internal values which are -50 to +50%.
Author: JK Controls (UK)
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