Good day,
Im a young engineer with only 5 months experience, so forgive me please eventual "funny" questions.
In last month i did some automation system, task was not thought - a tank with one inlet is filling continously tank with water, a pump with frequency converter is a "outlet". Main task is to keep water level stable in case of inlet flow change. Of course i have level measuring devices and flowmeters, so algorithm was not too complicated and one build-in PID (cont_c) is working very well. PLC had to do some other tasks with many digital and analog I/O's so we used a S7-300 station.
But as we know, college "knowledge" is not full, and real school starts when we do start work, so i would like use this simple object for some experiments - mostly in matter of PID regulation. Just want to try other regulation methods in case of extremally fast inlet flow changes, or flow measuring disturbances.
I did in MATLAB a mathematical model of this object. One tank (perfect integrator), one pump (inertial object) and a PID. Im treating measuring devices as "perfect" in mean not having influence for regulation process. My mathematical pump is acting like real one - answering with flow changes for 0-100 signal calculated by PID. And now i have problem ... how to simulate Simatic CONT_C PID algorithm ? Build-in MATLAB PID is quite nice, but calculating outlet signal as normal floating flow numbers without any limits. Other thing is that i have Siemens manual with drawning how CONT_C PID works, but theres no details how exacly inegrate and derivate parts do work, and how calculated value is transformed to 0-100% PID outlet signal. Know anybody how to solve this problem to get full mathematical model of complete real object ?
Thank you in advance
Greg
Im a young engineer with only 5 months experience, so forgive me please eventual "funny" questions.
In last month i did some automation system, task was not thought - a tank with one inlet is filling continously tank with water, a pump with frequency converter is a "outlet". Main task is to keep water level stable in case of inlet flow change. Of course i have level measuring devices and flowmeters, so algorithm was not too complicated and one build-in PID (cont_c) is working very well. PLC had to do some other tasks with many digital and analog I/O's so we used a S7-300 station.
But as we know, college "knowledge" is not full, and real school starts when we do start work, so i would like use this simple object for some experiments - mostly in matter of PID regulation. Just want to try other regulation methods in case of extremally fast inlet flow changes, or flow measuring disturbances.
I did in MATLAB a mathematical model of this object. One tank (perfect integrator), one pump (inertial object) and a PID. Im treating measuring devices as "perfect" in mean not having influence for regulation process. My mathematical pump is acting like real one - answering with flow changes for 0-100 signal calculated by PID. And now i have problem ... how to simulate Simatic CONT_C PID algorithm ? Build-in MATLAB PID is quite nice, but calculating outlet signal as normal floating flow numbers without any limits. Other thing is that i have Siemens manual with drawning how CONT_C PID works, but theres no details how exacly inegrate and derivate parts do work, and how calculated value is transformed to 0-100% PID outlet signal. Know anybody how to solve this problem to get full mathematical model of complete real object ?
Thank you in advance
Greg