Pid calculation and settings of parameters

[jcp]

Hi experts;
I attached a image in which i set the parameters which i found from an application which is almost similar to my task. I want to know the mathmetical calculation of these parameters to get the output value how i do it please give me example from the settings of attached image. Thanks advance.
Second i want to control two parameters but i see the PV must be %AI if i switch over the both %R for SP and %AI for PV what happen? If i use two PID what is the best way two use it point is output address is same.help me in this regard.
Now i give the figures
SP=9000
PV=8000
%AQ=?
setting see in the image
Regards

 

[bce123]

jcp, could you describe the acutal process you are trying to control

 

[jcp]

Hi;
Yes the actual process as under;
I have two input signals one for speed and one for temprature.
Suppose %AI1 have speed signal ans %AI2 have temprature signal. That is PV. and setpoint are speed and temprature also.
i want following
i start the engine the intial sp of speed is 62% when engine speed reaches the 28% (control by a bit and enable the PID )i want that the CV is given a ramp value of 0 to 32000 counts in eight second during this period if temprature increases the 350 deg f then it gives 32000 till speed equal to the SP that is 62%.
Now operator increase the speed that is SP and PV changes and when equals the SP of speed no increase in CV. If temprature at any stage reaches the 860 deg f or speed SP achive 100 % the output is stable no increase and no decrease in CV hold the value that is called TOPPING.
About the time to equal the PV to the SP of speed is as fast as possible.
But i read the PID i think it is use only with one %AI.
So i think on the following line
I calculate the error of speed and temprature both and then select the minimum error from these and apply to the setpoint like this i calculate the error of PV and select the minimum again from these and apply to the PV. But i do not know what output i get?
if i have a mathmetical sheet in excell to give the values and see the output in graph its good but i do not know about that type of software for GE 90-30 series but RSLOGIX 5000 PID tunner is available from the ROCKWELL to tune up the PID.
Regards

 

[bce123]

i do not know about that type of software for GE 90-30 series

sorry jcp i dont have the ge software. are you trying to use 3 pids, 1 for temp, 1 for speed and feed the outputs of both to a third for final control? have you tried the ISA website seems years ago they had a simulator on there but i have not been there in many years. maybe its time to drop in I think my membership expired 1990 somethng

 

[Steve Bailey]

At first reading it sounds to me like you need two PID loops, one for temperature and one for speed. The CV output of the temperature loop should be added to the SP of the speed loop.

What is the relationship between speed and temperature. Does increased speed cause an increase or a decrease in temperature?

 

[bce123]

jcp, I think IM lost in translation...

if i have a mathmetical sheet in excell to give the values and see the output in graph its good

Do you have spreadsheet or do you need it?
if you have it can you post it, it would help

sorry reread the OP I now see its a 2 part question.....
Lets make that 3 part....
PID (ISA) simulate before use

--------------------------------------------------------------------------------

Hi friends;
Is there any method or software for tune the PID before applying in the logic? I work on GE 90-30 CPU 352.
I want to give diffrent values to tune the pid and check its behaviour before finalize?
Regards

Its the same subject just more details.
Steve, I think I'll just bow to you on this one
Best of luck, Steve

 

[jcp]

Hi;
The relationship between speed and temprature as follows.
As speed increase temprature increase but do not enter in control while it achive 865 deg f. Suppose if speed reaches 98% and temprature is 865 then output of the PID limit to 50%. At that point if operator attempt to increase the speed from 98 to 100 the output of the pid not allowed to increase the speed.
The second creteria is if Temprature less than 865 deg f and speed reaches 100% then output must be limit at 50% that is 16000 counts. At that point if operator attempt to increase the speed the output not allowed to increase the speed.
I think when limits achived which one first come after that operator try to increase the speed the output must be decrease but give the appropriate value to maintain on that point where the limits achived.
"I have no excell sheet i required it please give me a complete address of website where pid ISA simulator available"
Regards

 

[bce123]

dont know if ISA still has one but try this excell

 

[jcp]

Hi;
Please do not laugh. I want to ask some basic quesstion about PID terms;
What is gain (K)?
what is gain (c)?
what is time constant and delay?
As describe my system how i calculate the values to proper tuneing of PID? What parameters i must know to calculate the tunning parameters?
Regards

 

[jcp]

Hi;
plz guide me.

 

[bce123]

try reading this:
http://en.wikipedia.org/wiki/PID_controller