Simulation for Control Valves

ChristianCasas,

You shouldn't have to model this for oscillations, since the model may not be accurate in any case. I am assuming you are doing this closed loop, with the flow measurement being fed back to the controller. If the controller and the flow control valves are specified properly (your supplier and/or the manufacturers can assist you in this). You can adjust your PID controller to yield the desired results. In general, depending on the time constants and nature of the actual flow and piping conditions, go very easy on the "D" (differential) factor, as this will be the most likely cause of oscillations. In many cases, you can dispense with any differential factor at all and still achieve the desired response.

I wouldn't trust a modeling program for this too much anyway.

Regards, Greg

it wont oscillate u can cary out by just using Forbes Marshal flow measuring device/ insturment. u can control flow on simulation also.

I think the input will be one and one is feedback signal and the output is also one. so that you can get a simple closed loop system. which you can write he conrol function of flow. then you can use simulink

you can also find the hydralic toolbaooks in the simulink. I think

so that you can get one is reference signal as input. the output or the water flow (flux) can be change into electronic signal by flux gauge, such as ultrasonic or other way, and feedback to input to compare with the reference signal you set up before, and use the eroor signal control the valve after amplify. I dontknow how to model the valve, but I guess it can be modeled as follow: flux= k*A where a is area of the valve open and k is a coeficent and again =V*k so the flux change into voltage you will measure. and the colse loope equation set up. now you can use simulink to simulation your model and result a fit adjustor. as Greg said there will be big tolerent in modeling, so you have to modify to fit your practice. #2 post is aalso one of the best bet for measure gauge.

I think you should get Visual Basic, and it would be easy to place the variables into text boxes, and adjust the driving variables, to see the effect on driven variables. Conversely, if you need to create a time driven model, you can also do this with the timer control, which allows the program to respond to regular events generated by the timer. You can also place command buttons into the program to simulate random events or acts of god. Lastly, you can add schematic diagrams to the form as a picture, and thereby place the textboxes at the correct locations such as control valves.

I have worked for years in HVAC industry creating system graphics, and mapping live data to them. You can download a working copy of Graphworx from the Iconics Website, or at least you used to be able to. this software is able to create simulated and animated graphics, and also uses VBA, so that you can write more complex algorigthms.

I do not know all the math that you are working with, but certainly VB could handle it. If any of what I've said is pertinent, and you are looking for help with the vb or the graphics, let me know. chrisg288@hotmail.com

Chris